Re: motor starting relay

On Sun, 28 Jan 2007 02:17:42 GMT, "Homer J Simpson"
<nobody@xxxxxxxxxxx> wrote:


"Maxwell" <luv2fly99@xxxxxxx> wrote in message
news:JwTuh.18131$8U4.9385@xxxxxxxxxxxxxxx

Well now, it does have a 5 hp contactor that works off a pressure switch
now. On at 150 psi, off at 175 psi. That contactor makes connection of the
two 120v legs that supply power. But it also has a spring loaded switch
that switches out the starting capacitors at about 1400 rpm or so, it's a
17XX rpm motor. The 5 hp contactor and power leads to the motor are
something different.

The relay I want to ad would switch on the starting capacitors immediately
when the power is switched on by the existing 5 hp contactor, and break
that connection about 1.5 seconds later. So although I know the main
contactor has to be rated for switching a 5 hp single phase motor, that
normally draws 23 amps ( nd has a lock rotor rating of much much more), I
don't know how much amperage is being supplied through, and has to be
broken, by the capacitor circuit. Now that I think about it, it's only
about a 14 or 16 gage wire, so it would have to be a lot less aperage than
the power legs though the 5 hp contactor. The contactor closes a 30 amp
circuit wired with #10 copper.

For sure you don't want the contacts to weld together however it may be that
the starting current through the cap start circuit is quite reasonable once
the motor gets up to speed.

---
"Quite reasonable"??? It goes to zero, you fucking moron, once the
motor gets up to a certain speed and the centrifugal switch opens,
disconnecting the caps from the starting winding. So you don't know
anything about motors, either? What a surprise.
---

So any half way reasonable contactor should
do the job OK - inc. a pre owned one!

---
"Half way reasonable"? What the hell is that goddam gobbledygook
supposed to mean?

Plus, the OP doesn't need a contactor, he needs a relay that
connects the capacitors to the starting winding when power is
connected to the motor via the 5HP contactor he's using now. Then
1.5 seconds or so later, he wants the relay to drop out and
disconnect the caps from the starting winding. He's stated that
very clearly, I think, so either you can't read worth a *** or your
reading comprehension is very, very poor. The turn-off delay
function is easily achievable, so the only thing that's up in the
air is how much current the relay contacts have to be able to
handle.

To the OP:

If you can measure the current in the starting winding and post what
you find then any number of us (except Homer) can help you pick a
suitable relay.


--
JF
.

Loading