On Sun, 28 Aug 2011 23:21:56 -0700, DaveC wrote:

I may be able to obtain a very small 2-pole 240 vac contactor I need rated
for 50 Hz only.

If I install it in N. America, what's the implication? Is the hold-in
magnetism less than if it were 60 Hz? Just noisy?

Please don't ask or suggest other sources. This is a very specific device and
I've not been able to locate other than this.

---
Not knowing the specifics about the coil makes predicting what will
happen at 60Hz difficult.

However, assuming that the inductive reactance and resistance of the
coil will remain constant at 50 and 60Hz means that the impedance of
the coil at 60Hz will be 1.2 times (60Hz/50Hz) what it is at 50Hz.

Consequently, the current in the coil at 60Hz will be about 83% of
what it is at 50Hz.

If that turns out to be a problem, a higher drive voltage could be
used in order to increase the current, namely 1.2 times 240V; 288V.


That could easily be accomplished using a transformer to boost the
240V mains to 288V, like this: (View with a fixed pitch font.)


240AC-----+--+
| |
oP||S
R||E
I||Co
| |
| +----- \
| 288AC TO COIL
240AC-----+-------- /

The transformer would need a 240V primary, a 48V secondary, and a VA
rating greater than or equal to the contactor coil's rating.

If you go he

http://www.signaltransformer.com/con...with-isolation

and select the input as 115/230 and the output as 48, you'll wind up
with 5 transformers rated at from 6 to 400 VA, one of which would
surely work.

Also, many manufacturers make similar transformers, and Digi-Key and
Mouser stock quite a few.


--
JF