3A.3.2.4 'Two Out Of Two' Relay Alarm System - Emerson Hydrastep 2468 series Operating Manual

Hydrastep 2468CB and 2468CD Manual

3a.3.2.4 'Two out of Two' Relay Alarm System

This system requires both relays to operate to cause an alarm when their assigned
electrodes register an alarm condition.
Case A - Relays normally energised, de-energise both to trip
(Relays shown in de-energised state)
RL 1
Odd electrodes
(RH input board)
RL 1
Odd electrodes
(RH input board)
Case B - Relays normally de-energised, energise both to trip
(Relays shown in de-energised state)
RL 1
Odd electrodes
(RH input board)
RL 1
Odd electrodes
(RH input board)
24685034
PL 2
1
To alarm annunciator
2
3
4
Alarm off when contacts closed
PL 2
1
2
3
To alarm annunciator
4
Alarm off when contacts open
(Switch SW5 is set to ES for low level alarms and set to EW for high level alarms)
PL 2
1
2
3
4
To alarm annunciator
Alarm off when contacts closed
PL 2
1
To alarm annunciator
2
3
4
Alarm off when contacts open
(Switch SW5 is set to ES for low level alarms and set to EW for high level alarms)
Relay Output Board Option
RL 1
PL 2
1
2
3
4
Even electrodes
(LH input board)
RL 1
PL 2
1
2
3
4
Even electrodes
(LH input board)
PL 2
1
2
3
4
PL 2
1
2
3
4
RL 1
Even electrodes
(LH input board)
RL 1
Even electrodes
(LH input board)
3a-11