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Relay Output Board Option Hydrastep 2468CB and 2468CD Manual
3a-10 24685034
3a.3.2.3 ‘One out of Two’ Relay Alarm System
Either of the relays involved can cause an alarm when their assigned electrode registers an
alarm condition. The alarm condition is selected by switch SW5 to provide relay energisation
in water EW or energisation in steam ES.
Case A - Relays normally energised, de-energise either one to trip
(Relays shown in de-energised state)
(Switch SW5 is set to ES for low level alarms and set to EW for high level alarms)
Alarm off when contacts closed
Even electrodes
(LH input board)
RL 1
To alarm annunciator
RL 1
Odd electrodes
(RH input board)
Alarm off when contacts open
Even electrodes
(LH input board)
RL 1
To alarm annunciator
RL 1
Odd electrodes
(RH input board)
1
4
3
2
1
4
3
2
PL 2
4
2
1
3
PL 2
1
4
3
2
PL 2
PL 2
Case B - Relays normally de-energised, energise either one to trip
(Relays shown in de-energised state)
(Switch SW5 is set to ES for low level alarms and set to EW for high level alarms)
Alarm off when contacts closed
Even electrodes
(LH input board)
RL 1
To alarm annunciator
RL 1
Odd electrodes
(RH input board)
Alarm off when contacts open
Even electrodes
(LH input board)
RL 1
To alarm annunciator
RL 1
Odd electrodes
(RH input board)
1
4
3
2
1
4
3
2
PL 2
4
2
1
3
PL 2
1
4
3
2
PL 2
PL 2