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BCU 560, BCU 565 · Edition 02.16
96
Parameters
11 .8 Valve check
11 .8 .1 Valve proving system
Parameter 51
Parameter 51 is used to define whether and at what time in
the BCU program sequence the valve check is activated. This
allows either the tightness of the gas solenoid valves and the
pipework between them to be checked (tightness test) or the
closed position of a solenoid valve (proof of closure function)
to be checked. If the proof of closure function is activated, the
closed position of the gas solenoid valve at the inlet side is
checked using a POC switch.
Parameter 51 = 0: Off. No valve check is activated.
Parameter 51 = 1: tightness test before start-up.
Parameter 51 = 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 51 = 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.
Parameter 51 = 4: proof of closure function (POC).
PZL
PZH
BCU 570..C1
µC
P
49
13
14
50
47
58
48
TC
PZL
PDZ
M
>750°
ϑ
1
2
3
V1
V2
45
GZL
A signal is sent to the BCU via the POC switch on the gas
solenoid valve on the inlet side before burner start-up stating
that the valve is closed. After burner start-up, the signal must
drop out to indicate to the BCU that the valve is open.
11 .8 .2 Relief valve (VPS)
Parameter 52
A valve connected to terminal 14 or 15 can be selected to act
as a relief valve during a tightness test.
PZH
BCU 560..C1F1
µC
VAS
TZI/TGI
V1
V2
V3
p
u
/2
14 15
13
45
9
5
52
55
54
53
56
47 48
58
ϑ
1
46
2
3
38
37
18
17
V
p1
V3
V2
14 15
V3
V2
Parameter 52 = 2: V2. The valve on terminal 14 acts as the
relief valve.
Parameter 52 = 3: V3. The valve on terminal 15 acts as the
relief valve.