3a-14

Relay Output Board Option

Hydrastep 2468CB and 2468CD Manual

3a.3.2.6 ‘Two out of Three’ Relay Alarm System

In the following diagrams (7A & 7B)  indicate the electrode channel selected for each relay. A fully functioning system (NO FAULTS) will cause a low level trip at electrode level 2. Using high-level electrode channels and SW5 set to ES, the circuit can perform a high level trip. Note: Inputs from electrodes 1 & 2 are applied to two separate relays on their respective boards.

Case A - Relays normally energised, de-energise two to trip

 

 

(Relays shown in de-energised state)

 

 

RL 1

1

PL 2

RL 1

1

PL 2

 

 

 

 

 

 

 

2

 

 

2

 

3

3

 

2

3

 

 

4

 

 

4

To alarm

 

 

 

annunciator

 

5

 

 

5

or tripping

 

 

 

device

RL 2

6

 

RL 2

6

 

 

 

 

 

 

7

 

2

7

 

1

8

 

8

 

 

 

 

 

 

 

 

RL 3

1

 

Even electrodes

 

 

 

 

(LH input board)

 

 

 

2

 

 

 

 

1

3

 

 

 

 

 

 

 

 

 

 

4

 

Alarm off when contacts closed

 

Odd electrodes

 

 

 

 

 

 

 

 

 

(RH input board)

 

PL 3

 

 

 

(Switch SW5 is set to EW for low-level alarms and set to ES for high-level alarms)

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

 

(Relays shown in de-energised state)

 

 

RL 1

PL 2

RL 1

 

PL 2

1

1

 

 

 

 

 

2

 

2

 

3

3

2

3

 

 

4

 

4

To alarm

 

 

annunciator

 

5

 

5

or tripping

 

 

device

RL 2

6

RL 2

6

 

 

 

 

 

7

2

7

 

1

8

8

 

 

 

 

 

 

 

 

Even electrodes

 

 

RL 3

 

(LH input board)

 

 

1

 

 

 

 

 

 

 

 

2

 

 

 

1

3

 

 

 

 

 

 

 

 

4

Alarm off when contacts open

 

 

 

 

 

Odd electrodes

PL 3

 

 

 

(RH input board)

 

 

 

 

 

 

 

(Switch SW5 is set to EW for low-level alarms and set to ES for high-level alarms)

3a-14

24685034

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Image 82
Emerson 2468CB, 2468CD manual 3a-14