Relays and Timers

[djcrzysounds@yahoo.com]

I was called to a church last week. Here is the picture since my scanner isn't working to give you a picture. Condensate Return Pumps for a boiler. There is an alternating relay (by Furnas) that was not working. Got a replacement from SQ D. Now to the wiring. Low water control wire (240V) comes into enclosure, feeds 2 delay on make timers and then the alternating relay. Each timer goes to one of the pump starters. each side of the alternating relay also goes to one of the 2 pump starters. The new relay will latch in either position 1 or 2, but when there is enough water in the boiler, the control circuit de-energizes but the alternating relay remains latched(electrically held), why doesn't it unlatch? I know the timers are there for 'redundancy' should one pump not work, the other one will turn on after approximately 1 minute(well both will be on but one should already be on)

 

[ptonsparky]

Not sure which relay you have, but most require that the power be removed from the coil each time it is set. Think of clicking a ball point pen. Others have a two leads, one for setting "A" position and another for "B". Again the power must be removed from the leads to allow alternating. The sequence happens after the power is applied.

Ck the wiring diagram for your replacement alternator, it may be just a bit different form the original.

 

[LarryFine]

The new relay will latch in either position 1 or 2, but when there is enough water in the boiler, the control circuit de-energizes but the alternating relay remains latched(electrically held), why doesn't it unlatch?

Are you sure it's not mechanically held? Could it be defective?

Can you test the coil for voltage when it should be dropping out?

 

[Jraef]

I'm very familiar with that Furnas* alternator relay but not with anything like it made by Square D, or anyone else for that matter. The closest thing I see them having is a 9039XG1 but it would operate and wire completely differently from that Furnas alternator. If you tried to simply drop it in as a replacement, it would not have worked.

* Unfortunately no longer made by Siemens but still available from Hubbell Industrial Controls.
http://www.hubbell-icd.com/icd/components/ac5247.asp