1.1.1 Stage-controlled main burner with alternating pilot burner

Control:
Main burner ON/OFF or High/Low

The main burner can be started with reduced capacity after the operating signal from the pilot burner has been detected. The pilot burner is switched off automatically after the main burner has started up. When the main burner is switched off, the pilot burner automatically switches on again. This reduces the main burner start-up time.

The UV sensor monitors the flame signal from pilot and main burners.

The BCU provides the cooling and purging processes.

1.1.2 Main burner with permanent pilot burner

Control:
Main burner ON/OFF or High/Low

The main burner can be started with reduced capacity after the operating signal from the pilot burner has been detected. Pilot and main burners can be operated simultaneously. This reduces the time required by the main burner for starting up.

The BCU provides the cooling and purging processes.

1.1.3 Two-stage-controlled main burner with permanent pilot burner

Control:
Main burner ON/OFF with ignition via bypass

The main burner can be started with minimum capacity after the operating signal from the pilot burner has been detected. When the operating state is reached, the BCU issues the enable signal for the maximum burner capacity. Pilot and main burners can be operated simultaneously. This reduces the time required by the main burner for starting up.

The BCU provides the cooling and purging processes.

1.1.4 Staged control

The BCU activates butterfly valve BVA and moves it to the pre-purge position. In the event of a temperature demand, the burner control unit BCU activates input DI 1 via the output at terminal 65 and moves the butterfly valve to the ignition position (condition: the IC 40 must have reached the ignition position on the instant of ignition). The burner starts. The burner application “Burner 1 with pilot gas” (parameter A078 = 1) is selected so that the burner can be started with a limited start fuel flow rate. To activate the high-fire rate, DI 2 is actuated via the air valve output at terminal 66 of the BCU. The butterfly valve moves cyclically between the high-fire rate position and the low-fire rate position, see Air actuator, Operating mode 11.

1.1.5 Modulating control with defined ignition position

The central control system starts the pre-purge. Input DI 2 is activated via the air valve output of the BCU and the butterfly valve BVA is set to the pre-purge position.

In the event of a temperature demand, the burner control unit BCU activates input DI 1 via the output at terminal 65 and moves the butterfly valve to the ignition position (condition: the IC 40 must have reached the ignition position on the instant of ignition). The burner starts.

The burner application “Burner 1 with pilot gas” (parameter A078 = 1) is selected so that the burner can be started with a limited start fuel flow rate.

During operation, the BCU activates DI 1 and DI 2 using outputs 65 and 66. This enables the analogue input IN on the actuator IC 40. Depending on the capacity demand of the temperature controller, the butterfly valve BVA moves steplessly to the position between the low-fire rate and the high-fire rate as specified by the analogue input IN, see Air actuator, Operating mode 27.

1.1.6 Flame control using the temperature

In high temperature systems (temperature > 750°C), the flame may be controlled indirectly via the temperature. As long as the temperature in the furnace chamber is below 750°C, the flame must be controlled by conventional methods.

If the temperature in the furnace chamber rises above the spontaneous ignition temperature of the gas/air mixture (> 750°C), the FCU signals to the burner control units via the fail-safe HT output that the furnace system is in High temperature mode (HT). When the HT input is activated, the burner control units switch to High temperature mode.

They operate without evaluating the flame signal and their internal flame control systems are non-functional.

If the furnace temperature falls below the spontaneous ignition temperature (< 750°C), the FCU disconnects the HT output from the electrical power supply. There is no longer an active signal at the HT inputs of the burner control units. The flame signals are monitored once again by the UV sensor or flame rod.

In the event of a fault in a temperature monitoring component (e.g. sensor discontinuity, sensor short-circuit) or in the event of a mains failure, the flame control task is transferred to the burner control units.

1.1.7 ON/OFF rotary impulse control

For processes which require a turndown of more than 10:1 and/or those which require heavy circulation of the furnace atmosphere to ensure a uniform temperature, e.g. heat treatment furnaces operating at low and medium temperatures in the metallurgical industry.

With ON/OFF cyclic control, the capacity supplied to the process is controlled by means of a variable ratio of the operating time to the pause time. In this type of control, the burner output pulse frequency always maintains full momentum and results in maximum convection in the furnace chamber, even with regulated heating.

The pneumatic ratio control system controls the gas pressure on the burner proportionally to the air pressure and thus maintains a constant air/gas ratio. At the same time, it acts as a low air pressure protection device.

The ignition and monitoring of the individual burners is ensured by burner control unit BCU 480 with power module LM..F3.

The centrally checked safety functions such as pre-purge, tightness test, flow detector and pressure switch check (gas_min., gas_max., air_min.) are provided by the FCU 500.

1.1.8 Modulating burner control

The centrally checked safety functions such as pre-purge, setting the valve to ignition position via a butterfly valve control system, tightness test, flow detector and pressure switch check (gas_min., gas_max., air_min.) are provided by the FCU 500. The capacity can be adjusted continuously by activating the control element (analogue or 3-point step signal).

To ensure that the correct air volume is available for ignition (start fuel flow rate) when starting the burners, the FCU sends the burner start enable signal to the BCUs via the “LDS (limits during start-up)” output.

The circuit design of the safety interlock and LDS outputs on the FCU and the corresponding inputs on the BCUs ensures that the burners can only start if the safety interlocks and the LDS output have enabled burner start-up.

1.1.9 PROFINET connection using bus module BCM

The bus system transfers the control signals from the automation system (PLC) to the BCU/BCM for starting, resetting, controlling the air valve, purging the furnace or for cooling and heating during operation. In the opposite direction, it sends operating status, the level of the flame signal and the current program status.

Control signals that are relevant for safety, such as the safety interlocks, purge and HT input, are wired independently of the bus communication using separate cables.

3.2.1 BCU 480..E1/LM 400..F3..E1 with ionization control in double-electrode operation

Alternative flame control, see Flame control

Electrical connection, see Electrical connection

Explanation of symbols, see Legend

3.2.2 BCU 480..P3..E1/LM 400..F3..E1 with industrial plug for ionization control in double-electrode operation

Alternative flame control, see Flame control

Electrical connection, see Electrical connection

Explanation of symbols, see Legend

In the case of UV control, use Elster UV sensors for intermittent operation (UVS 5, 10) or flame detectors for continuous operation (UVC 1).

Pilot burner = double-electrode operation/main burner = ionization

Pilot burner in double-electrode operation

Ionization control for main burner

Parameter I004 = 0.

Pilot burner = single-electrode operation/main burner = ionization

Parameter I004 = 0.

Pilot burner = single-electrode operation/main burner = UVS

Parameter A001 ≥ 5 µA.

Parameter I004 = 3.

Pilot burner = single-electrode operation/main burner = UVC

Parameter I004 = 4.

Pilot burner = UVS/main burner = ionization

Parameter A002 ≥ 5 µA.

Parameter I004 = 5.

Pilot burner = UVC/main burner = UVC

Parameter I004 = 2.

Pilot burner = UVC/main burner = ionization

Parameter I004 = 7.

3.2.4 Assignment of connection terminals

Control input (AC mains voltage)

Safety circuit input (AC mains voltage)

Input ( µA)

Output (AC mains voltage), supply voltage

Supply voltage

Voltage supply + safety circuit input (AC mains voltage)

Valve outputs (AC mains voltage)

Outputs (AC mains voltage)

Floating contact

4.1.1 BCU..F1

The BCU with LM..F1 activates a control element via the outputs for capacity control (terminals 64 to 67) for purging, cooling or starting the burner. This control element moves to the required position for the relevant operating situation.

As soon as there is a purge signal at terminal 3 of BCU, the control element is activated by the outputs for capacity control to approach the position for pre-purge. The protective system (FCU 500) starts the pre-purge time if there is adequate air flow. After the elapse of the pre-purge time, the control element moves to the ignition position. Once the protective system (terminal 35, safety interlocks) has issued the enable signal, the pilot and main burners can be started by the start-up signals at terminals 1 and 5. The control element can be activated to control the burner’s capacity dependent on parameters A048 and A049.

Modulating control

Parameter I020 = 2, A048 = 2

After the operating signal has been received from the burner, the BCU issues the controller enable signal via the output at terminals 65 and 66. Access to the control element is thus transferred to an external temperature controller. The temperature controller controls the burner capacity (air volume) on the basis of the required temperature.

Detailed information about parameter I020, see Air actuator.

Staged control

A048 = 0, 1 or 2

Depending on parameters A048 and A049, the control element may be activated either by the program or externally via the input at terminal 4, see also Air actuator control and Air actuator on start-up can be activated externally.

4.1.2 BCU..F3

The BCU with LM..F3 activates an air valve for purging, cooling or starting the burner. The required air capacity is released by the air valve.

As soon as there is a purge signal at terminal 3 of BCU..F3, the air valve is activated by the output at terminal 65. The protective system (FCU 500) starts the pre-purge time if there is adequate air flow. After the elapse of the pre-purge time, the air valve closes for ignition. Once the protective system (terminal 35, safety interlocks) has issued the enable signal, the burner can be started by the start-up signal at terminal 1. The gas valves for the 1^st stage are opened and the burner is ignited (on the BCU..C1 after a successful valve check). After the operating signal has been received from the burner, the gas valve for the 2^nd stage opens.

Staged control

A048 = 0, 1 or 2

Depending on parameters A048 and A049, the control element may be activated either by the program or externally via the input at terminal 4, see also Air actuator control and Air actuator on start-up can be activated externally.

5.1.1 Test instant

Depending on the parameter setting, the tightness control checks the tightness of the pipework and the gas solenoid valves before each start-up and/or after each shut-down of the burner, see Valve proving system.

The gas line is always safeguarded by a gas solenoid valve during this check.

Before burner start-up

The valve check is started when the start-up signal is present at terminal 1. The BCU checks the tightness of the gas solenoid valves and the pipework between the valves. The gas line is always safeguarded by a gas solenoid valve during this check. The pilot burner is ignited when pre-purge is ended and the tightness has been checked successfully.

After burner shut-down

After the burner has been shut down, the BCU checks the tightness of the gas solenoid valves and the pipework between them. Once the test has been carried out successfully, the next burner start is enabled. The BCU immediately conducts a tightness test if mains voltage is available or if it is reset after a fault lock-out.

An additional bypass/relief valve must be installed in gas sections with an air/gas ratio control. This ensures that the test volume V_p1 can be vented during the tightness test with the air/gas ratio control closed.

5.1.2 Program sequence

The tightness test starts by checking the external pressure switch.
If pressure p_Z > p_u/2, program A starts.
If pressure p_Z < p_u/2, program B starts.

Program A

Valve V1 opens for the opening time t_L set in parameter A059. V1 closes again. During the measurement time t_M, the tightness control checks the pressure p_Z between the valves.

If pressure p_Z is less than half the inlet pressure p_u/2, valve V2 is leaking.

If pressure p_Z is greater than half the inlet pressure p_u/2, valve V2 is tight. Valve V2 is opened for the set opening time t_L. V2 closes again.

During the measurement time t_M, the tightness control checks the pressure p_Z between the valves.

If pressure p_Z is greater than half the inlet pressure p_u/2, valve V1 is leaking.

If pressure p_Z is less than half the inlet pressure p_u/2, valve V1 is tight.

The tightness test can only be performed if pressure p_d downstream of V2 is around atmospheric pressure and the volume downstream of V2 is at least 5 × higher than the volume between the valves.

Program B

Valve V2 opens for the set opening time t_L. V2 closes again. During the measurement time t_M, the tightness control checks the pressure p_Z between the valves.

If pressure p_Z > p_u/2, valve V1 is leaking. If pressure p_Z < p_u/2, valve V1 is tight. Valve V1 is opened for the set opening time t_L. V1 closes again.

During the measurement time t^M, the tightness control checks the pressure p^Z between the valves.

If pressure p_Z < p_u/2, valve V2 is leaking.

If pressure p_Z > p_u/2, valve V2 is tight.

The tightness test can only be performed if pressure p_d downstream of V2 is around atmospheric pressure and the volume downstream of V2 is at least 5 × higher than the volume between the valves.

5.1.3 Test period t_P

Depending on the burner capacity, the tightness of the gas solenoid valves must be checked in accordance with the relevant application standard, e.g. EN 676, EN 746, NFPA 85 and NFPA 86.

The test period t_P is calculated from:

• Opening times t_L for V1 and V2,
• Measurement times t_M for V1 and V2.

5.1.4 Opening time t_L

Standard EN 1643:2000 allows a maximum opening time of 3 s for the tightness test if the main gas valves are actuated directly. If gas can flow into the combustion chamber when a valve is opened, the gas volume must not exceed 0.083% of the maximum flow rate.

5.1.5 Measurement time t_M

The sensitivity of the tightness control in the BCU can be adjusted for each individual system by adapting the measurement time t_M. The longer the measurement time t_M, the greater the sensitivity of the tightness control. The measurement time is set using parameter A056 to a value between 3 and 3600 s, see Measurement time for V_p1 .

For one test volume V_p1 between 2 gas solenoid valves

For a large test volume V_p1 with reduced testing time

Conversion into US units, see www.adlatus.org

Leakage rate

The BCU tightness control makes it possible to check a specific leakage rate Q_L. Within the European Union, the maximum leakage rate Q_L is 0.1% of the maximum flow rate Q_(N)max. [m³/h].

Test volume V_p1

Test volume V_p1 is calculated from the valve volume V_V, added to the volume of the pipe V_R for each additional metre in length L.

The measurement time required for the test volume V_p1 must be set on the basis of the calculation using parameter A056.

Calculation examples

2 valves VAS 665,
distance L = 9.5 m,
inlet pressure p_u = 50 mbar,
max. flow rate Q_(N)max. = 200 m³/h.

Test volume V_p1 = 1.1 l + 9.5 m x 3.3 l/m = 32.45 l

Measurement time for test volume V_p1:

Set the next highest value (20 s) using parameter 56, see Measurement time for V_p1 .

7.2.1 Device master data file (GSD), electronic data sheet (EDS)

The technical properties of a device are described by the manufacturer for PROFIBUS and PROFINET in a device master data file (GSD file) or for EtherNet/IP in an electronic data sheet (EDS). The GSD/EDS file is required to integrate the device (BCU) in the configuration of the PLC. The GSD/EDS file contains the device image, the communications properties and all fault messages from the device in text form which are important for configuring the PROFINET network and the data exchange. Modules defined in the GSD/EDS file may be selected for configuration to integrate the device. The GSD/EDS file for the bus module can be obtained from www.docuthek.com. The steps required to integrate the file are described in the instructions for the engineering tool for your automation system.

7.3.1 Modules for process data

All modules required for data exchange between the PLC and the burner control unit BCU are shown in the following table.

Inputs/Outputs

The digital input and output signals from the burner control unit BCU are included in this module.

Input bytes (BCU ➔ PLC)

The input bytes describe the digital signals which are transferred from the BCU to the digital inputs of the PLC. The digital signals take up 3 bytes (24 bits).

Output bytes (PLC ➔ BCU)

The output bytes describe the digital signals which are output by the PLC to the BCU. The digital signals to control the burner control unit BCU occupy 2 bytes (16 bits).

Terminals 1 to 41 (dependent on parameters I061 to I074) can be wired parallel to the bus communication. This allows the BCU to be controlled using the digital signals of the bus communication or the inputs at the terminals.

1) Terminals 1 to 41 (dependent on parameters I061 to I074) can be wired parallel to the bus communication.

2) Only with BCU 465 depending on the parameter settings.

Burner 1 flame signal (BCU ➔ PLC)

The flame signal for burner 1 is transferred from the BCU to the PLC as an analogue value using this module. The flame signal occupies one byte with values from 0 to 255 (= flame signal from 0 to 25.5 µA).

¹⁾ See code tables “BusCommunication_BCU4_R2.xlsx” at www.docuthek.com.

Burner 2 flame signal (BCU ➔ PLC)

The flame signal for burner 2 is transferred from the BCU to the PLC as an analogue value using this module. The flame signal occupies one byte with values from 0 to 255 (= flame signal from 0 to 25.5 µA).

¹⁾ See code tables “BusCommunication_BCU4_R2.xlsx” at www.docuthek.com.

Status signal (BCU ➔ PLC)

This module transfers the status signals from the BCU to the PLC. The status signals occupy one byte (0 to 255). Every status signal is allocated a code. The allocation is described in the code table “BusCommunication_BCU4_R2.xlsx”.

¹⁾ See code tables “BusCommunication_BCU4_R2.xlsx” at www.docuthek.com.

Fault and warning signals (BCU ➔ PLC)

The fault and warning signals are transferred from the BCU to the PLC using this module. The fault and warning signals each occupy one word.

The same allocation table applies to the fault signals and the warning signals.

¹⁾ See code tables “BusCommunication_BCU4_R2.xlsx” at www.docuthek.com.

Remaining times (BCU ➔ PLC)

This module transfers the remaining times of various processes from the BCU to the PLC. The remaining time occupies one word.

Temperature (BCU ➔ PLC)

This module transfers the internal device temperature. The temperature occupies one word.

BCU input information (BCU ➔ PLC)

This module transfers the signal states of the digital inputs on the BCU to the PLC.

BCU output information (BCU ➔ PLC)

This module transfers the signal states of the digital outputs on the BCU (via output terminals and bus) to the PLC.

¹⁾ Only with BCU 465 depending on the parameter settings.

7.3.2 Device parameters and statistics

With the help of acyclic communication between the PLC and BCU, it is possible to read information on parameters, statistics and fault history on an event basis (e.g. using system function block Siemens FSB 52 RDREC).

The available data records differ in terms of their indexes (PROFINET) or instances (EtherNet/IP). The contents and description of the indexes/instances are described in the code table “BusCommunication_BCU4_R2.xlsx” (download from www.docuthek.com).

10.3.2 Burner 1 flame signal FS1 switch-off threshold

Parameter A001

The sensitivity at which the burner control unit still detects a flame at burner 1 can be set using parameter A001.

As soon as the measured flame signal falls below the set value (2 to 20 µA), the BCU performs a fault lock-out during start-up after the elapse of safety time 1 (parameter A094) or during operation after the elapse of the safety time during operation (parameter A019).

In the case of UV control, this value can be increased, should the burner to be monitored be influenced by other burners, for example.

The adjustable range for the flame signal switch-off threshold for burner 1 is dependent on the setting of interface parameter I004, see Flame control:
I004 = 0, 3 or 4 (ionization control of burner 1): 2–20 µA,
I004 = 1, 5 or 6 (control of burner 1 using UVS sensor): 5–20 µA,
I004 = 2 (control of burner 1 using UVC sensor): 5 µA

10.3.3 Burner 2 flame signal FS2 switch-off threshold

Parameter A002

The sensitivity at which the burner control unit still detects a flame at burner 2 can be set using parameter A002.

As soon as the measured flame signal falls below the set value (2 to 20 µA), the BCU performs a fault lock-out during start-up after the elapse of safety time 2 (parameter A096) or during operation after the elapse of the safety time during operation (parameter A019).

In the case of UV control, this value can be increased, should the burner to be monitored be influenced by other burners, for example.

The adjustable range for the flame signal switch-off threshold for burner 2 is dependent on the setting of interface parameter I004 (Flame control):
I004 = 0, 5 or 7 (ionization control of burner 2): 2–20 µA,
I004 = 1, 3 or 8 (control of burner 2 using UVS sensor): 5–20 µA,
I004 = 2, 4 or 6 (control of burner 2 using UVC sensor): 5 µA*

* The switch-off threshold is set at the UVC sensor.

10.3.4 Flame simulation check in standby position

Parameter A003

This defines the instant for the flame simulation check.

Parameter A003 = 0: flame simulation check in standby position. The flame simulation check is conducted provided no start-up signal (start 1) is applied (during the so-called start-up position/standby). This allows fast start-up of the burner since there is no waiting time t_W.

The burner must have been switched off for at least 4 s before start-up in order for the flame simulation check to be conducted correctly.

Parameter A003 = 1: flame simulation check on start-up. The flame simulation check is conducted after applying the start-up signal (start 1 or start 2) during the waiting time t_W.

What is flame simulation?

Flame simulation means that an extraneous signal is detected as a flame signal out of sequence. If the BCU detects such an extraneous signal during the flame simulation check, it starts the flame simulation delay time t_LV1 (pilot burner) or t_LV2 (main burner) for 25 s each. If the extraneous signal disappears during this time, the pilot or main burner can start. Otherwise, a fault lock-out occurs.

Flame simulation during t_LV1:
E 01 flashes on the display.

Flame simulation check in standby position (parameter A003 = 0):

Flame simulation check on start-up (parameter A003 = 1):

The flame simulation check of the pilot burner is always active until valve V3 is enabled.

Flame simulation during t_LV2 (with permanent pilot burner only):
E 05 flashes on the display.

Flame simulation check in standby position (parameter A003 = 0):

Flame simulation check on start-up (parameter A003 = 1):

The flame simulation check of the main burner is always active until valve V2 is enabled.

10.3.5 High temperature operation

Parameter A006

Operation of firing systems above 750°C. The BCU..D1 and BCU..D2 have a fail-safe input with the function “High temperature operation”. If firing systems are operated above 750°C, the system is considered to be an item of high temperature equipment (see EN 746-2). Here, flame control must be in operation until the furnace wall temperature has exceeded 750°C.

Below 750°C, the flame is monitored by conventional means (UV sensor or flame rod). In High temperature mode (> 750°C), the flame may be controlled via the temperature using a safety temperature monitor (STM) in order to increase the system’s availability. This means that no incorrect flame signals, e.g. signals from a UV sensor which interprets reflected UV radiation as extraneous signals, may lead to faults.

When the HT input is activated (terminal 6), the burner control unit reverts to High temperature mode, i.e.: the BCU operates without evaluation of the flame signal. The safety function of the device’s internal flame control system is deactivated.

In High temperature mode, the gas valves are opened and the burners are started as usual without monitoring the presence of a flame.

The precondition for this operating mode is that an external flame supervision device ensures the presence of the flame in a fail-safe manner indirectly via the temperature. For this purpose, we recommend a safety temperature monitor with double thermocouple (DIN 3440). The flame must be monitored again by conventional means (UV sensor or flame rod) in the event of sensor discontinuity or short-circuit, failure of the safety temperature monitor or power failure.

The voltage may be applied to the HT input (terminal 6) so as to activate High temperature operation only when the temperature at the furnace wall has exceeded 750°C.

If the temperature in the furnace chamber drops below 750°C, the HT input must be disconnected from the electrical power supply and the furnace must then be operated with flame control.

The BCU then responds, depending on setting:

Parameter A006 = 0

The High temperature mode function is switched off. Flame control takes place dependent on the setting in parameter I004 using a flame rod, a UVS sensor or a UVC sensor.

Parameter A006 = 2 (BCU..D1)

The BCU switches off burner 1 and burner 2 and restarts with flame simulation check (recommended in the case of UV control with UVS).

Parameter A006 = 3 (BCU..D1)

The burners remain in operation and the BCU performs flame control again on both burners (recommended for ionization control or UV control with UVC).

Parameter A006 = 6 (BCU..D2)

The BCU switches off burner 1 and restarts it with flame simulation check. Burner 2 continues to operate as long as no flame failure occurs.

If no flame signal is present when High temperature mode is deactivated, the burner control unit performs a fault lock-out, regardless of parameter A006.

Pilot burner fault

Main burner fault

10.4.1 Burner 1 start-up attempts

This parameter defines the maximum number of possible start-up attempts of burner 1.

Taking into account national standards and requirements, it must be clarified whether multiple start-up attempts are permitted.

In accordance with EN 746-2, a restart may be conducted only if the safety of the installation is not impaired.

Multiple start-up attempts are not permitted under NFPA 86. If no flame forms during start-up, this must result in a fault lock-out..

If no flame is detected during start-up, an immediate fault lock-out (A007 = 1) or up to two additional start-up attempts (A007 = 2, 3) are performed depending on parameter A007.

Parameter A007 = 1: 1 start-up attempt.

If no flame is formed during the start-up, so that at the end of the safety time t_SA1 no flame signal is detected, this will result in a BCU safety shut-down with subsequent fault lock-out. The fault message E 04will flash in the BCU display depending on the burner operating mode.

Parameter A007 = 2, 3:
2 or 3 start-up attempts.

If no flame is formed during the start-up, so that at the end of the safety time t_SA1 no flame signal is detected, the BCU closes the gas valves and repeats the start-up. Each start-up attempt begins with the parameterized start-up behaviour.

If the safety time t_SA1 elapses without a flame signal having been detected, even after the last parameterized start-up attempt, this will result in a BCU safety shut-down with subsequent fault lock-out. The fault message E 04will flash in the BCU display depending on the burner operating mode.

10.4.2 Burner 2 start-up attempts

Parameter A008

This parameter defines the maximum number of possible start-up attempts of burner 2.

Taking into account national standards and requirements, it must be clarified whether multiple start-up attempts are permitted.

In accordance with EN 746-2, a restart may be conducted only if the safety of the installation is not impaired.

Multiple start-up attempts are not permitted under NFPA 86. If no flame forms during start-up, this must result in a fault lock-out..

If no flame is detected during start-up, an immediate fault lock-out (A008 = 1) or up to two additional start-up attempts (A008 = 2, 3) are performed depending on parameter A008.

Parameter A008 = 1: 1 start-up attempt.

If no flame is formed during the start-up, so that at the end of the safety time t_SA2 no flame signal is detected, this will result in a BCU safety shut-down with subsequent fault lock-out. The fault message E 04will flash in the BCU display depending on the burner operating mode.

Parameter A008 = 2, 3: 2 or 3 start-up attempts.

If no flame is formed during the start-up, so that at the end of the safety time t_SA2 no flame signal is detected, the BCU closes the gas valves and repeats the start-up. Each start-up attempt begins with the parameterized start-up behaviour.

If the safety time t_SA2 elapses without a flame signal having been detected, even after the last parameterized start-up attempt, this will result in a BCU safety shut-down with subsequent fault lock-out. The fault message E 08will flash in the BCU display depending on the burner operating mode.

10.4.3 Burner application

Parameter A078

This parameter enables the BCU to be adjusted to various burner applications. In addition, an optional pilot gas valve (V3) can be parameterized via which the burner is started with a defined ignition capacity.

Parameter A078 = 0: burner 1. Two valves (V1, V2) are included for the burner. These are connected to the valve outputs (terminals 60 and 61). Valves V1 and V2 are opened in parallel to start the burner in order to release the gas supply to the burner.

Parameter A078 = 1: burner 1 with pilot gas. Three valves (V1, V2 and V3) are included for a burner with a pilot gas valve. These are connected to the valve outputs (terminals 60, 61 and 62). Valves V1 and V3 open to start the burner. The burner is started with a limited ignition capacity using gas valve V3. After the elapse of the safety time t_SA1 (program step 02), valve V2 opens. Valve V3 limits the ignition capacity. After the elapse of the flame proving period t_FS1 (program step 04), it is closed again.

For this application, it must be ensured that the flame proving period (parameter A095) is set to a value ≥ 2 s.

Parameter A078 = 2: burner 1 and burner 2. Three valves (V1, V2 and V4) are included for a modulating burner with a pilot burner. These are connected to the valve outputs (terminals 60, 61 and 63). Valves V1 and V4 open to start the pilot burner. Gas valve V2 releases the gas supply to the main burner.

Parameter 78 = 3: burner 1 and burner 2 with pilot gas. In this application, the burner has an additional pilot gas valve V3. The valves are connected to the valve outputs (terminals 60, 61, 62 and 63). Valves V1 and V4 open to start the pilot burner. The burner is started with a limited ignition capacity using gas valve V3. After the elapse of the safety time t_SA2 (program step 06), valve V2 opens (terminal 61). Pilot gas valve V3 is closed again after the elapse of the flame proving period t_FS2 (program step 07).

For this application, it must be ensured that the flame proving period (A097) is set to a value ≥ 2 s.

Parameter A078 = 4: two-stage burner 1. Three valves (V1, V2 and V3) are included for a two-stage burner. These are connected to the valve outputs (terminals 60, 61 and 62).

Valves V1 and V3 open to start the burner. The burner is started with a limited ignition capacity using gas valve V3. After the flame proving period t_FS1 has elapsed, valve V2 opens to enable the 2^nd gas stage.

Parameter 78 = 5: burner 1 and two-stage burner 2. In this application, the burner has an additional pilot gas valve V3. The valves are connected to the valve outputs (terminals 60, 61, 62 and 63). Valves V1 and V4 open to start the pilot burner. The burner is started with a limited ignition capacity using gas valve V3. Valve V2 (terminal 61) can be opened with the operating signal (program step 08) in order to operate burner 2 at maximum capacity.

10.4.4 Pilot burner

Parameter A079

Burner 1 (pilot burner) is used to ignite burner 2 (main burner). The start-up/operating properties of burner 1 can be set using parameter A079.

Parameter A079 = 0: with shut-down.

Burner 2 is started if burner 1 is in operation and start-up signal 2 is active. As soon as safety time t_SA2 has just one second left to run, burner 1 is switched off regardless of start-up signal 1.

If start-up signal 2 is deactivated while burner 2 is in operation and start-up signal 1 is active, burner 1 is restarted. Burner 2 is deactivated as soon as burner 1 is in operation.

Parameter A079 = 1: controlled externally.

Burner 1 is started and deactivated depending on start-up signal 1. Burner 1 continues to operate even if the main burner is active.

Burner 2 can only be started if burner 1 is in operation.

Parameter A079 = 2: to start.

Burner 1 is started with start-up signal 1. Afterwards, burner 2 is started. As soon as safety time t_SA2 has just one second left to run, burner 1 is deactivated regardless of the start-up signal. The start-up signal has no effect on the burner start.

Burner 2 is deactivated if start-up signal 2 is deactivated during operation. Burner 1 can be restarted after it has been shut down and after a successful flame simulation check by activating start-up signal 1.

10.4.5 Safety time 1 t_SA1

Parameter A094

During safety time 1 t_SA1, the flame (pilot flame) is ignited. It can be set to between 2 and 15 s.

Safety time 1 starts with the application of the ϑ1 signal (terminal 1). The valves open at the start of safety time 1. The fuel supply to burner 1 is released so that a flame can form. If no flame is detected at the end of safety time 1, the valves are closed again. Depending on parameter A007 (Burner 1 start-up attempts), the BCU reacts either with an immediate safety shut-down with fault lock-out (A007 = 1) or with one or two additional start-up attempts (A007 = 2 or 3). The BCU will complete a maximum of three start-up attempts.

Safety time 1 must be determined on the basis of current national standards and regulations. The burner application and the burner capacity are the main criteria for this.

If the ϑ1 signal (terminal 1) drops out during safety time 1, the valves will not be switched off until the end of safety time 1.

10.4.6 Flame proving period 1 t_FS1

Parameter A095

Flame proving period 1 (t_FS1) can be parameterized to enable the flame on burner 1 to stabilize after the elapse of safety time 1. Only when the flame proving period has elapsed will the next program steps be initiated by the BCU. The flame proving period can be set to between 0 and 25 s.

10.4.7 Safety time 2 t_SA2

Parameter A096

During safety time 2 t_SA2, the flame on burner 2 (main flame) is ignited. It can be set to between 2 and 10 s.

Safety time 2 starts with the application of the ϑ2 start-up signal (terminal 5). Valve V2 opens at the start of safety time 2. The fuel supply to burner 2 is released so that a flame can form. If no flame is detected at the end of safety time 2, the valves are closed again. Depending on parameter A008 (Burner 2 start-up attempts), the BCU reacts either with an immediate safety shut-down with fault lock-out (A008 = 1) or with one or two additional start-up attempts (A008 = 2 or 3). The BCU will complete a maximum of three start-up attempts.

Safety time 2 must be determined on the basis of current national standards and regulations. The burner application and the burner capacity are the main criteria for this.

If the ϑ1 start-up signal (terminal 1) drops out during safety time 2, valve V4 will not be switched off until the end of safety time 2.

10.4.8 Flame proving period 2 t_FS2

Parameter A097

Flame proving period 2 t_FS2 can be parameterized to enable the flame on burner 2 to stabilize after the elapse of safety time 2. Only when the flame proving period has elapsed will the next program steps be initiated by the BCU. The flame proving period can be set to between 0 and 25 s.

10.5.1 Restart

Parameter A009

Restart can be programmed for burners which occasionally display unstable behaviour during operation.

This parameter determines whether the BCU initiates an immediate fault lock-out or an automatic restart after a safety shut-down during operation. Excessive restarts, however, can be detected.

Taking into account national standards and requirements, it must be clarified whether the restart function may be used.

In accordance with EN 746-2, a restart may be conducted only if the safety of the installation is not impaired.

The precondition for an automatic restart is that the burner can restart (as intended in all operating phases). In this case, it must be ensured that the program sequence started by the BCU matches the application.

Parameter A009 = 0: Off.

A safety shut-down with subsequent fault lock-out takes place in the event of flame failure during operation.

Parameter A009 = 1: burner 1. The restart function is active.

If a safety shut-down occurs during operation (minimum operating time of 2 s), the valves are closed and the operation signalling contact is opened within the safety time during operation t_SB. The burner control unit then attempts to restart the burner once. If the burner does not function, a safety shut-down with fault lock-out occurs. The display blinks and shows the fault message.

Parameter A009 = 2: burner 2.

If a safety shut-down occurs during operation (minimum operating time of 2 s), valve V2 is closed and the operation signalling contact opened within the safety time during operation t_SB. The burner control unit then attempts to restart burner 2 once. If burner 2 does not function, a safety shut-down with fault lock-out occurs. The display blinks and shows the fault message.

Parameter A009 = 3: burner 1 and burner 2.

Parameter A009 = 4: max. 5 × in 15 min. for burner 1. The restart function is active and is also monitored for excessive restarts.

In certain conditions, it is possible that the restart function is repeated continuously without a safety shut-down with subsequent fault lock-out being performed. The BCU has a safety shut-down with subsequent fault lock-out option if more than 5 restarts are performed within a period of 15 minutes.

Taking into account national standards and requirements, it must be clarified whether the option may be used.

Parameter A009 = 5: max. 5 × in 15 min. for burner 2.

Parameter A009 = 6: max. 5 × in 15 min. for burner 1 and burner 2.

10.5.2 Minimum operating time t_B

Parameter A061

A minimum operating time (0 to 250 s) may be defined to ensure that the heating equipment operates stably.

If the minimum operating time is active, burner operation will be maintained until the set time has elapsed even if the start-up signal fails.

The minimum operating time starts as soon as the program step for operation/controller enable (display 08) has been reached.

If the start-up signal drops out before the start of operation/controller enable, e.g. during pre-purge, the burner control unit reverts directly to the start-up position (standby) and the burner is not ignited.

The minimum operating time can be cancelled by switching off the BCU or if a safety shut-down occurs.

10.6.1 Safety time during operation

Parameter A019

Parameter A019 = 0; 1; 2; 3; 4: time in seconds

The safety time during operation is the time that the BCU needs to stop the fuel supply after a flame failure during operation or an interruption at the safety current inputs (terminals 36, 37 and 38). The safety time can be set to between 0 and 4 s in steps of 1 s. Prolonging the safety time during operation increases the installation availability in the case of brief-duration signal fades (e.g. fades of the flame signal).

The requirements of national standards and regulations must be satisfied.

In accordance with EN 298, the maximum reaction time to a flame failure must not exceed 1 s. Specific application standards may permit other values.

Under EN 746-2, the safety time of the installation during operation (total closing time) must not exceed 3 s.

Under NFPA 86, section 8.10.3*, the maximum flame failure response time shall be ≤ 4 s.

10.7.1 Over-run time t_NL

Parameter A039

The air valve remains open for the programmed time (0 to 60 s) after the start-up signal ( ϑ) has been deactivated following a controlled shut-down. The burner control unit closes the actuator (air valve, actuator) after the elapse of the over-run time t_NL.

10.7.2 Running time selection

Parameter A041

Parameter A041 = 0: Off; checking the positions for minimum/maximum capacity. A signal that the positions for minimum and maximum capacity have been reached is returned and monitored with a timeout time of max. 250 s. When the position has been reached, the BCU will initiate the next program step.

Parameter A041 = 1: On; for approaching the positions for minimum/maximum capacity. The running time set using parameter A042 is activated for approaching these positions, see Running time. After this time has elapsed, the BCU will initiate the next program step.

Parameter A041 = 2: On; for approaching the position for maximum capacity. The running time set using parameter A042 is activated for approaching the position for maximum capacity, see Running time. After this time has elapsed, the BCU will initiate the next program step. Approaching the position for minimum capacity is signalled and monitored.

Parameter A041 = 3: On; for approaching the position for minimum capacity. No signal is returned that the position for minimum capacity has been reached. The running time set using parameter A042 is activated for approaching the position for minimum capacity, see Running time. After this time has elapsed, the BCU will initiate the next program step. Approaching the position for maximum capacity is signalled and monitored.

10.7.3 Running time

Parameter A042

This parameter can be used to adjust the behaviour in the case of slow opening and closing air valves. The running time starts when the air actuator is switched off. A restart of the burner after a controlled shut-down, a start-up attempt, restart, cooling or purging is delayed until the end of the running time. After the running time has elapsed, the burner is started if the start-up signal ( ϑ) is applied.

The time should be adjusted such that the system can be set to ignition position, i.e. that the air actuator is closed before a start-up is initiated.

10.7.4 Over-run

Parameter A043

The over-run (t_KN) supports applications with a pneumatic air/gas ratio control system and On/Off control. Using the over-run function reduces the O₂ content in the furnace atmosphere.

Parameter A043 = 0: Off. No over-run is performed. The gas circuit is closed immediately owing to a quick closing gas valve in the case of On/Off control. The air circuit is closed more slowly. The air flowing in during this time increases the O₂ content in the combustion chamber.

Parameter A043 = 1: post-ventilation (with BCU/LM..F1 only). The gas supply will be closed. Air continues to be supplied for the programmed duration depending on parameter A039.

Parameter A043 = 2: low fire over-run until actuator feedback. The air actuator is closed with a deactivated start-up signal in the event of a controlled shut-down. The gas valves remain open for the programmed duration depending on parameter A039 (Over-run time) or until the air actuator is closed. The gas valves are closed immediately in the event of a flame failure. A flame failure during the over-run does not result in a fault lock-out.

Parameter A043 = 3: low fire over-run, time-bound.

The burners are initially powered down to low-fire rate and remain in operation for the programmed duration depending on parameter A039 (Over-run time). Flame control is still operational. It must be ensured that no excess gas occurs.

10.7.5 Air actuator control

Parameter A048

In cyclic operation, parameters A048 and A049 on BCU..F1 and F3 determine the behaviour of the air actuator during burner start and burner operation.

The air actuator can be activated externally via the input at terminal 4 for cooling the burner in the start-up position (standby). This function is not available during burner start-up and during operation.

Parameter A048 = 0: opens on external activation.

This setting together with parameter A049 = 0, see Air actuator on start-up can be activated externally, is required for burners on which the air/gas ratio is controlled by a pneumatic air/gas ratio control system and which need to be started at low-fire rate, e.g. on two-stage-controlled burners, see Two-stage-controlled main burner with permanent pilot burner. In this case, activation of the air actuator during burner start via the input at terminal 4 must be prevented.

External control allows switchover between low fire and high fire during operation.

Parameter A048 = 1: opens with gas stage 1 (start fuel flow rate).

The air actuator opens at the same time as safety time t_SA2 begins and the main burner starts.

Parameter A048 = 2: opens with gas stage 2 (operating fuel flow rate).

This setting is required in the case of two-stage main burners which are switched ON/OFF via the ϑ2 input.

The air valve opens simultaneously with the operating signal for the main burner. The air valve can be activated externally via the input at terminal 4 for cooling the burner in the start-up position/standby. This function is not available during burner start-up and during operation.

Parameter 48 = 1: opens with V4 burner 1.

The air valve opens with the start fuel flow rate. The air valve can be activated externally via the input at terminal 4 for cooling the burner in the start-up position/standby.

10.7.6 Air actuator on start-up can be activated externally

Parameter A049

Parameter A049 = 0: cannot be activated.

During start-up, the air actuator remains closed. The air actuator cannot be activated externally.

Parameter A049 = 1: can be activated externally.

The air actuator can be activated externally via the input at terminal 4 during start-up. Parameter A048 must be set to 0 for this purpose, see also Air actuator control.

10.7.7 Air actuator in the event of fault

Parameter A050

This parameter decides whether the air actuator can be activated externally via the input at terminal 4 in the event of a fault lock-out.

Parameter A050 = 0: cannot be activated. The air actuator remains closed in the event of a fault lock-out. It cannot be activated externally via terminal 4.

Parameter A050 = 1: can be activated externally. The air actuator can be activated externally via the input at terminal 4 during a fault, e.g. for cooling.

10.7.8 Combustion mode

Parameter A074

The type of combustion in which the ignition takes place can be set using parameter A074.

Parameter A074 = 0: Flame mode.

The burner is always started with ignition in Flame mode and in High temperature mode. Flame control is provided in High temperature mode by the high temperature monitoring system.

Parameter A074 = 3: high temperature operation without burner 1 start.

When connected to pilot and main burners, the BCU 480 can be parameterized so that the main burner is started automatically in HT mode. The pilot burner’s start-up process is skipped. The start-up signals for burner 1 and burner 2 must be active.

10.8.1 Valve proving system

Parameter A051

Parameter A051 is used to define whether and at what time in the BCU program sequence the valve check is activated. The tightness of the gas solenoid valves and the pipework between the valves are checked (tightness test). Parameter A051 = 0: Off. No valve check is activated.

Parameter A051 = 0: Off. No valve check is activated.

Parameter A051 = 1: tightness test before start-up.

Parameter A051 = 2: tightness test after shut-down. With this setting, a tightness test is also performed after a fault is reset and after mains on.

Parameter A051 = 3: tightness test before start-up and after shut-down.

An additional bypass valve must be installed in gas sections with an air/gas ratio control. This valve allows the closed air/gas ratio control to be bypassed during the tightness test.

10.8.2 Relief valve (VPS)

Parameter A052

One of the valves connected to terminal 61, 62, 63 or 64 can be selected to discharge the test volume during a tightness test.

Parameter A052 = 2: V2. The valve on terminal 61 acts as the relief valve.

Parameter A052 = 3: V3. The valve on terminal 62 acts as the relief valve.

Parameter A052 = 4: V4. The valve on terminal 63 acts as the relief valve.

Parameter A052 = 5: V5. The valve on terminal 64 acts as the relief valve.

10.8.3 Measurement time for V_p1

Parameter A056

The required measurement time must be determined according to the requirements of the appropriate application standards, e.g. EN 1643.

The required measurement time for the tightness test of V_p1 can be set using parameter A056. It is adjustable from 3 to 3600 s.

See also Measurement time t_M .

10.8.4 Valve opening time t_L1

Parameter A059

This parameter is used to define the opening time for the valves (2 to 25 s) which are opened to fill or discharge the test volume between the gas valves. If the preset opening time t_L = 3 s is inadequate (e.g. if slow opening valves are used) to fill the test volume or reduce the pressure between the valves, bypass valves can be used instead of the main valves.

On condition that the gas volume which flows into the combustion chamber is no larger than 0.083% of the maximum flow rate, the opening time of the bypass valves may be longer than the 3 s permitted by the standard (EN 1643:2000).

10.9.1 Minimum pause time t_MP

Parameter A062

A minimum pause time t_MPP (0 to 3600 s) can be defined to achieve stable operation of the burners. If the over-run time set using parameter A039 has elapsed and no start-up signal is received at terminal 1 and terminal 5 (burner shut down), a restart and cooling are prevented for the duration of the minimum pause time t_MP.

If a signal is applied to terminal 1 (burner start-up) or terminal 2 (cooling) during the minimum pause time, status display Delay HO will appear.

10.10.1 Operating time in Manual mode

Parameter A067

Parameter A067 determines when Manual mode is terminated.

Parameter A067 = 0: Manual mode is not limited in time.

If this function has been selected, operation of the burner may be continued manually in the event of failure of the control system or the bus activation.

Parameter A067 = 1: the BCU will terminate Manual mode 5 minutes after the last time the button is pressed. It then moves abruptly back to the start-up position (standby).

If the unit is switched off or a power failure occurs, Manual mode on the BCU will be terminated regardless of parameter A067.

10.11.1 Function of sensor 1

Parameter A101

This parameter assigns a sensor function to terminal 36.

Parameter A101 = 48: proof of closure function V1. The closed position of valve V1 is monitored by the POC.

Parameter A101 = 49: proof of closure function V2. The closed position of valve V2 is monitored by the POC.

Parameter A101 = 50: proof of closure function V3. The closed position of valve V3 is monitored by the POC.

Parameter A101 = 51: proof of closure function V4. The closed position of valve V4 is monitored by the POC.

Parameter A101 = 52: proof of closure function V5. The closed position of valve V5 is monitored by the POC.

Parameter A101 = 53: tightness test. The pressure switch signal for the tightness test is evaluated.

10.11.2 Function of sensor 2

Parameter A102

Terminal 37 is assigned a sensor function using parameter A102.

The value ranges and descriptions for the parameter are identical to parameter A101, see Function of sensor 1.

10.11.3 Function of sensor 3

Parameter A103

Terminal 38 is assigned a sensor function using parameter A103.

The value ranges and descriptions for the parameter are identical to parameter A101, see Function of sensor 1.

10.11.4 Proof of closure function test period

Parameter A060

Parameter A060 = 0 to 6000 s: testing time for the closed position of one of the gas valves V1, V2, V3, V4 or V5.

When the start-up signal is received at terminal 1, the BCU checks that one of the gas valves (V1 to V5) is in its closed position using the POC switch. If a signal is not received from the POC switch at terminal 36, 37 or 38, depending on parameter A101, A102 or A103, after the set testing time (gas valve is closed), the BCU performs a fault lock-out with fault message “ E c 1”.

As soon as the BCU has opened the gas valve, it queries the open position of the valve via the POC switch. If a signal is still being received from the POC switch at terminal 36, 37 or 38 after the set testing time, the BCU performs a fault lock-out with fault message “ E c 8”.

10.12.1 Fieldbus communication

Parameter A080

Fieldbus communication can be enabled using parameter A080 when bus module BCM 400 is connected.

A device name/network name must be entered in the automation system/BCSoft for the unique identification of the control unit (BCU/FCU) in the fieldbus system.

Parameter 80 = 0: Off. Fieldbus communication is disabled. Parameterization access using BCSoft via Ethernet is not possible.

Parameter 80 = 1: with address check. The device name/network name on delivery, for example for the BCU 460, is “not-assigned-bcu-460-xxx”. The expression “not-assigned-” must be deleted or may be replaced with an individual name. The sequence xxx must be identical to the address set on the BCM 400 using the code switches (xxx = address in the range 001 to FEF).

Code switch setting: upper switch (S1) = 10² (hundreds), centre switch (S2) = 10¹ (tens), lower switch (S3 = 10⁰ (ones)

Parameter 80 = 2: no address check. The device name/network name can be selected as specified by the automation system.

10.12.2 K-SafetyLink

Parameter A081

In furnace control systems, consisting of FCU 50x and BCU 46x, the SafetyLink communications protocol is used to transfer safety-critical signals between the FCU and BCU. The data transfer can be enabled using parameter A081.

Parameter A081 = 0: Off. No data exchange takes place via K-SafetyLink.

Parameter A082 = 1: On. Data exchange via K-SafetyLink is enabled. The FCU must support this function.

10.12.3 Safety interlocks (bus)

Parameter A085

This parameter defines the interface through which the signal from the safety interlocks is received.

Parameter A085 = 1: via fail-safe bus

Parameter A085 = 2: via terminal

Parameter A085 = 5: via fail-safe bus and terminal

10.12.4 Purge (bus)

Parameter A087

This parameter defines the interface through which the signal for purging is received.

Parameter A087 = 0: Off

Parameter A087 = 1: via fail-safe bus

Parameter A087 = 2: via terminal

Parameter A087 = 3: via non-fail-safe bus

Parameter A087 = 4: via fail-safe bus or terminal

10.12.5 High temperature operation (bus)

Parameter A088

This parameter defines the interface through which the signal for High temperature mode is received.

Parameter A088 = 0: Off

Parameter A088 = 1: via fail-safe bus

Parameter A088 = 2: via terminal

Parameter A088 = 5: via fail-safe bus and terminal

10.12.6 LDS (bus)

Parameter A089

This parameter defines the interface through which the LDS signal (limits during start-up) is received.

Parameter A089 = 0: Off

Parameter A089 = 1: via fail-safe bus

Parameter A089 = 2: via terminal

Parameter A089 = 5: via fail-safe bus and terminal

10.13.1 Flame control

Parameter I004

Parameter I004 = 0: flame control is performed with a flame rod.

Parameter I004 = 1: flame control is performed with a UV sensor for intermittent operation (UVS).

Parameter I004 = 2: flame control is performed with a UV sensor for continuous operation (UVC).

Parameter I004 = 3: burner 1 flame control is performed with a flame rod, burner 2 flame control is performed with a UV sensor for intermittent operation (UVS).

Parameter I004 = 4: burner 1 flame control is performed with a flame rod, burner 2 flame control is performed with a UV sensor for continuous operation (UVC).

Parameter I004 = 5: burner 1 flame control is performed with a UV sensor for intermittent operation (UVS), burner 2 flame control is performed with a flame rod.

Parameter I004 = 6: burner 1 flame control is performed with a UV sensor for intermittent operation (UVS), burner 2 flame control is performed with a UV sensor for continuous operation (UVC).

Parameter I004 = 7: burner 1 flame control is performed with a UV sensor for continuous operation (UVC), burner 2 flame control is performed with a flame rod.

Parameter I004 = 8: burner 1 flame control is performed with a UV sensor for continuous operation (UVC), burner 2 flame control is performed with a UV sensor for intermittent operation (UVS).

Flame control using UV sensors

For intermittent operation, the operating state of the complete system is limited to 24 h pursuant to EN 298. To meet the requirement for intermittent operation, the burner is shut down and restarted automatically after a continuous operating time of 24 hours if it is not operated in compliance with the standard. The restart does not meet the requirements of EN 298 for UV sensor continuous operation because the required self-test (at least once per hour) is not performed while the burner is operating. This shut-down and subsequent restart are performed in the same way as a normal controlled shut-down. Depending on the parameterization, the burner is started with or without pre-purge. This process is controlled independently by the BCU and therefore it must be checked whether the industrial process permits the pause in heat supply it creates.

The reaction times of the BCU and UV sensor for continuous operation are coordinated so that the set safety time during operation (parameter A019) is not extended.

10.13.2 Air actuator

Parameter I020

Parameter I020 = 2: IC 40. To ensure that the actuator IC 40 can be operated on the BCU..F1, parameter I020 = 2 (capacity control) must be set. The operating mode of actuator IC 40 may be parameterized to 11 or 27.

The positions for maximum capacity and ignition capacity can be set using the actuator. Terminal 41 checks whether the position for maximum capacity has been reached. Terminal 40 checks the position for ignition capacity. If the position is not reached within the timeout time of 250 s, a safety shut-down of the BCU will be performed. A fault message ( E Ac, E Ao or E Ai) will be displayed, see Fault messages.

If a controller enable is active, the control system is enabled for operation via the outputs at terminals 65 and 66.

Operating mode 11

Operating mode 11 allows cyclic operation (ON/OFF and OFF/Low/High/OFF).

The actuator IC moves to the “High fire” position during the controller enable procedure. There is no timeout active in this case.

Operating mode 27

During the controller enable procedure, the actuator IC 40 can be adjusted infinitely between the positions for maximum and minimum capacity using its analogue input (terminals 18 and 19). There is no timeout active in this case.

Fault

In the event of a fault, there will be no signal at terminals 65 and 66 so that the actuator moves to the closed position. When approaching the closed position, no timeout of 250 s is active since no feedback input is checked. This may result in a situation where the program is continued in the case of a request for the closed position, without the butterfly valve being closed. The outputs at terminals 64 (controller enable) and 67 (closed position) on the BCU are non-functional and are not activated.

Manual mode

In Manual mode, no external controller is enabled. The actuator can be moved to the positions for maximum capacity or ignition capacity by the user. 3-point step operation is not possible. No timeout is active when approaching these positions.

Parameter I020 = 5: air valve. The positions for maximum capacity and ignition capacity can be set using the air valve. If the air valve is closed, the ignition capacity is reached; if it is open, the maximum capacity is reached.

Parameter A042 (Running time) can be used to adjust the behaviour in the case of slow opening and closing air valves, so that the system can be set to ignition position before a start-up is initiated, see Running time. Parameter A041 (Running time selection) must be set to 1 to adjust this behaviour.

10.13.3 Function of terminal 64

Parameter I040

Terminal 64 can be assigned a function using parameter I040 depending on the power module LM..F1 or LM..F3. Alternatively, the output can be actuated using a bus system.

Parameter I040 = 0: Off. The output has no function.

Parameter I040 = 2: valve V5. Terminal 64 can be used to activate a fifth valve. This option can only be selected if power module LM..F3 is used.

Parameter I040 = 3: bus output 1. The output at terminal 64 can be actuated using a bus system. Can only be selected with power module LM..F3.

10.14.1 Contact 80, 81/82 function

Parameter I050

Parameter I050 = 0: Off. The contact will not be closed. It has no function

Parameter I050 = 1: ready signal. The contact is closed if the BCU is ready (switched on) and there is no fault signal.

Parameter I050 = 2: air signal. The air signal is activated as soon as a connected air actuator has reached or exceeded its High position (max. position).

Parameter I050 = 3: purge signal. The contact is closed while purging is active.

Parameter I050 = 4: cooling air valve. The contact is closed if the cooling air valve is to be actuated.

Parameter I050 = 6: fault signal. The contact is closed if a fault lock-out is active.

Parameter I050 = 7: burner 1 operating signal. The contact is closed if burner 1 is in operation.

Parameter I050 = 8: burner 2 operating signal. The contact is closed if burner 2 is in operation.

10.14.2 Contact 90, 91/92 function

Parameter I051

For a description and the parameter values, see Contact 80, 81/82 function.

10.14.3 Function of contact 95/96

Parameter I052

For a description and the parameter values, see Contact 80, 81/82 function.

10.14.4 Function of contact 95/97

Parameter I053

For a description and the parameter values, see Contact 80, 81/82 function.

10.14.5 Contact 85/86, 87 function

Parameter I054

For a description and the parameter values, see Contact 80, 81/82 function.

10.15.1 Function of input 1

Parameter I061

To define the input signal for terminal 1.

Parameter I061 = 0: Off. The input has no function.

Parameter I061 = 4: safety interlocks. The “safety interlocks” signal can be applied via the input and/or SafetyLink. No start-up is commenced if there is no signal at the input. If the signal drops out during operation, the gas valves are closed immediately (< 1 s).

Parameter I061 = 5: air. The BCU receives the signal for controlled air flow or for external air actuator control through the input.

Parameter I061 = 6: cooling air. The BCU receives the signal to actuate the cooling air actuator through the input.

Parameter I061 = 7: air actuator R1. The BCU receives the feedback signal for the ignition position from actuator IC 40 through the input.

Parameter I061 = 8: air actuator R2. The BCU receives the feedback signal for the High position from actuator IC 40 through the input.

Parameter I061 = 9: start 1. The BCU receives the start-up signal for the pilot burner (start 1) through the input.

Parameter I061 = 10: start 2. The BCU receives the start-up signal for the main burner (start 2) through the input.

Parameter I061 = 11: reset. The BCU receives the signal for a remote reset through the input.

Parameter I061 = 12: purge. The BCU receives the purge signal through the input.

Parameter I061 = 13: LDS. The BCU does not perform a burner start-up, restart or start-up attempt until the central actuator is in ignition position, see the application example on Modulating control with defined ignition position. To ensure that the burners only start with the start fuel flow rate, the higher-level control system sends a signal to start the burner through the terminal to the BCU.

Parameter I061 = 14: high temperature operation. This input is used to signal to the burner control unit that the furnace system is in High temperature mode (HT). The burner control unit switches to High temperature mode when the HT input is activated. It operates without evaluating the flame signal and its internal flame control system is non-functional.

10.15.2 Function of input 2

Parameter I062

To define the input signal for terminal 2.

For parameter values and descriptions, see Function of input 1.

10.15.3 Function of input 3

Parameter I063

To define the input signal for terminal 3.

For parameter values and descriptions, see Function of input 1.

10.15.4 Function of input 4

Parameter I064

To define the input signal for terminal 4.

For parameter values and descriptions, see Function of input 1.

10.15.5 Function of input 5

Parameter I065

To define the input signal for terminal 5.

For parameter values and descriptions, see Function of input 1.

10.15.6 Function of input 6

Parameter I066

To define the input signal for terminal 6.

For parameter values and descriptions, see Function of input 1.

10.15.7 Function of input 7

Parameter I067

To define the input signal for terminal 7.

For parameter values and descriptions, see Function of input 1.

10.15.8 Function of input 35

Parameter I068

To define the input signal for terminal 35.

On a BCU..E1 (power supply via L1), this input should be reserved for the safety interlock signal (I068 = 4). On a BCU..E0, this input is connected to the power supply for the safety-relevant outputs and cannot be parameterized otherwise.

For all other parameter values and descriptions, see Function of input 1.

10.15.9 Function of input 36

Parameter I069

To define the input signal for terminal 36.

A sensor may be connected to this input (I069 = 1, 2 or 3) if necessary.

Parameter I069 = 1: sensor 1

Parameter I069 = 2: sensor 2

Parameter I069 = 3: sensor 3

For all other parameter values and descriptions, see Function of input 1

10.15.10 Function of input 37

Parameter I070

To define the input signal for terminal 37.

A sensor may be connected to this input (I070 = 1, 2 or 3) if necessary.

Parameter I070 = 1: sensor 1

Parameter I070 = 2: sensor 2

Parameter I070 = 3: sensor 3

For all other parameter values and descriptions, see Function of input 1.

10.15.11 Function of input 38

Parameter I071

To define the input signal for terminal 38.

A sensor may be connected to this input (I071 = 1, 2 or 3) if necessary.

Parameter I071 = 1: sensor 1

Parameter I071 = 2: sensor 2

Parameter I071 = 3: sensor 3

For all other parameter values and descriptions, see Function of input 1.

10.15.12 Function of input 39

Parameter I072

To define the input signal for terminal 39.

For parameter values and descriptions, see Function of input 1.

10.15.13 Function of input 40

Parameter I073

To define the input signal for terminal 40.

For parameter values and descriptions, see Function of input 1.

10.15.14 Function of input 41

Parameter I074

To define the input signal for terminal 41.

For parameter values and descriptions, see Function of input 1.

13.3.1 Safety current inputs

Actuation of the safety current inputs only with switchgear featuring mechanical contacts. If switchgear with semiconductor contacts is used, the safety current inputs must be connected using relay contacts.

To safeguard the safety current inputs, the fuse must be designed so that the sensor with the lowest switching capacity is protected.

The cabling outside enclosed installation spaces must be protected from mechanical damage and stress (e.g. vibration or bending) as well as short-circuits, short-circuits to ground and cross-circuits.

Calculation

I_N = current of the sensor/contactor with the lowest switching capacity

Suitable fuse = 0.6 × I_N

14.3.1 Opto-adapter PCO 200

Including BCSoft CD-ROM,
Order No.: 74960625.