Opto-isolated Output Board Option Hydrastep 2468CB & 2468CD Manual
3c-10 24685034
3c.3.2.3 ‘One out of Two’ Opto-output Alarm System
Either of the opto-outputs involved can signal an alarm when their assigned electrode detects
a water/steam interface change. The alarm condition is selected by switch SW5 to provide
an opto-output in conducting mode in water W or in a conducting mode in steam S.
Case A - Opto-output circuit normally open circuit, short circuit either one to trip
TR2
(Switch SW5 is set to S for low level alarms and set to W for high level alarms)
Opto-output 1
TR2
Opto-output 1
+ VE - VE
Even Electrodes
(LH Input Board)
Note: External power must
be applied as shown.
See specification for
power requirements
Odd Electrodes
(RH Input Board)
1
4
3
2
PL 2
1
4
3
2
PL 2
To alarm annunciator or
tripping device
Case B - Opto-output circuit normally short circuit, open circuit either one to trip
TR2
(Switch SW5 is set to W for low level alarms and set to S for high level alarms)
Opto-output 1
TR2
Opto-output 1
+ VE - VE
Even Electrodes
(LH Input Board)
Note: External power must
be applied as shown.
See specification for
power requirements
Odd Electrodes
(RH Input Board)
1
4
3
2
PL 2
1
4
3
2
PL 2
To alarm annunciator or
tripping device
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