Re: Pump monitoring (again)

["Frank Mc Alinden" <frankmc@xxxxxxxxxxxxxxxx>]

Hi John

The relays shown on your Maplin link are suitable for your
application...You
need to determine which 2 contacts are the relay coil (in your case the
relay coil must be 240v ac) ....you can do this with a multimeter
..according to the website the resistance is around 15k.....
One   the coil connections will connect to the neutral and the other coil
connection will go to the wire you have determined live when a pump is
turned on........

Im not sure how your going to connect your 1 wire circuit to the relay
contacts?? I dont think you need a double pole ???

At home and work i tend to use Omron (ice cubes) relays as the coil
connection is on the opposite side to the contact connection , good
seperation of 240v / low voltage and also easy to recognise
connections...Below is a link to these on RS website....

http://tinyurl.com/o6n74

HTH
Frank



----- Original Message -----
From: "Benfield, John (Penta)" <john.benfield-eds@xxxxxxx>
To: <ukha_d@xxxxxxx>
Sent: Friday, February 24, 2006 12:04 AM
Subject: [ukha_d] Pump monitoring (again)


>I need someone to confirm my understanding of how relays work and will
> do what I am expecting.
>
> In my quest to monitoring my central heating I am looking at a way of
> monitoring when the various pumps come on. I already have a hardwired
> controller that links all of the timers/thermostats/pumps together.
The
> controller has a screw terminal block within it and I have worked out
> which terminals go live for each pump. What I *think* I now need it a
> 230v relay attached to these.
>
> My really really basic understanding of a relay (such as this
> http://tinyurl.com/kwtd2) is that when
a voltage is applied across one
> set of contacts, the pair on the other side of the relay either open
or
> close. Am I correct in assuming that the 230v does not get passed
> through the relay to the second contacts - this will destroy my 1-wire
> sensors.
>
> Looking at the various relays out there I guess I need a DPDT 5a 230v,
> does this sound correct?
>
> JB
>
>
>
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