BCU 460, BCU 465 · Edition 11.19
48
Valve proving system
6 .2 Proof of closure function
The proof of closure function monitors the function of
a gas solenoid valve (V1, V2, V3 or V4). A limit switch on
the gas solenoid valve signals the closed position of the
valve to the BCU for this purpose. Parameter I073 must
be set to 3 in this case, see page 116 (Function of in-
put 38).
Parameter A101, A102 or A103 is used to define the
valve from which the signal for the closed position must
be received:
A101, A102 or A103 = 48 (V1), 49 (V2), 50 (V3), 51 (V4),
see page 103 (Function of sensor 1).
PZL
PZH
BCU 46x..C1
µC
P
36
60
61
37
47
58
48
TC
PZL
PDZ
M
>750°
ϑ
1
2
V1
V2
38
GZL
By checking the closed position using the proof of clo-
sure function, the BCU complies with the requirements
of NFPA 85 (Boiler and Combustion Systems Hazards
Code) and NFPA 86 (Standard for Ovens and Furnaces).
6 .2 .1 Program sequence
When the start-up signal is received at terminal 1, the
BCU checks that the valve is in its closed position using
the POC switch. If a signal is not received at terminal 38
from the POC switch after a timeout time of 10 s (valve
is closed), the BCU performs a fault lock-out with fault
message “E c1”.
As soon as the BCU has opened the valve, it queries the
open position of the valve via the POC switch. If a sig-
nal is still being received at terminal 38 from the POC
switch after a timeout time of 10 s, the BCU performs a
fault lock-out with fault message “E c8”.