Pumps control

[MNMANS]

Hi all,

Our client is requesting the addition of a backup level control system (Float switches), to control the pumps in the event of the failure of the primary level control instruments(ultrasonic level) and/or the PLC. Is it possible to wire the backup system (float switches) to the PLC so it's automatically in use in the event of the primary level control failure and have it hardwired as well to control the pumps in the events of PLC failure.
Thanks. Your help is highly appreciated.

 

[itsmoked]

The client is asking for non-PLC backup. You would use a separate contactor and the float would control it directly or thru a simple relay.

You then carefully set the float up to operate the pump at levels slightly beyond the original control points. Higher for the TURN-ON and higher for the TURN-OFF.

You also make sure the contactors are identically phased so if both end up on the pump spins in the right direction and no phases are shorted.

Keith Cress
kcress -

http://www.flaminsystems.com