Emerson 2468CD, 2468CB manual 3b-13

Hydrastep 2468CB and 2468CD Manual Delay Relay Output Board Option

3b.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	1	PL 2	PL 2	1	RL 1
			To alarm annunciator
	2			2
	3			3
	4			4
Odd electrodes					Even electrodes
(RH input board)					(LH input board)

Alarm off when contacts closed

RL 1	1	PL 2	PL 2	1	RL 1
	2			2
	3			3
	4		To alarm annunciator	4
Odd electrodes					Even electrodes
(RH input board)		Alarm off when contacts open			(LH input board)
	(Switch SW5 is set to ES for low level alarms and set to EW for high level alarms)

Case B - Relays normally de-energised, energise both to trip

(Relays shown in de-energised state)

RL 1	PL 2	PL 2	1	RL 1
1
2			2
3			3
4	To alarm annunciator		4
Odd electrodes				Even electrodes
(RH input board)				(LH input board)

Alarm off when contacts closed

RL 1	1	PL 2	PL 2	1	RL 1
	2		To alarm annunciator	2
	3			3
	4			4
Odd electrodes					Even electrodes
(RH input board)		Alarm off when contacts open			(LH input board)
	(Switch SW5 is set to ES for low level alarms and set to EW for high level alarms)

24685034 3b-13