User manual

Model: 2100 &2300 Series

2100UM22.DOC Rev: 2.2

- 22 -

 Conditions 1, 3, 5, 7 are typically for control applications where the positive action i.e. turning

on a pump, should be shut off during a power failure to the Arjay level controller.

 Conditions 2, 4, 6, 8 are typically for alarm applications where the positive action i.e.

sounding an alarm if the level is at a high level, should also be in place during a power failure

to the Arjay level controller.

4.3.4 RELAY SETTINGS EXAMPLES

1- A Pump is desired to be turned on to pump out the contents of a tank when the level

exceeds 90% and then turned off when the level drops below 20%. In the event of the Arjay

unit failing or a power failure, the pump should be shut off to prevent if from pumping dry.

Settings:

High control point: 90%

Low control point: 20%

Failsafe: No

Relay action: High acting

Contacts used: Normally Open

Explanation:

In this case the positive action is turning on a pump.

Since the pump should be turned off if the Arjay unit fails or in the event of a power failure i.e. the

positive action state is not the same as the failure state, the failsafe setting should be No.

Since the positive action is desired when the level exceeds the high control point then the relay

setting should be High Acting.

Since the pump starter requires power to turn on the pump and the failsafe is No, the normally

open contacts should be used.

The time delay may be set to some convenient value to minimize relay chatter. Even with no

time delay, relay chattering due to the level fluctuating around the high control point is in this case

not a problem since the once the relay is energized, it is not de-energized until the level drops

below the 20% level.

2- A receiving tank must be filled by turning on a pump when the level drops below 20%. The

tank must then be filled to a capacity of 90% before the pump is shut off. In the event of

an instrument or power failure, the pump should be shut off to prevent overfilling the

receiving tank.