On Mon, 29 Aug 2011 07:25:23 -0700 (PDT), the renowned NT
wrote:

On Aug 29, 7:21*am, 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.

Thanks,
Dave

IME relays pull in at in the region of half rated voltage, and dc
ratings are typically about half the voltage of the ac rating, which
gives an idea of how much current is determined by L and how much by
R. Running your relay on 220v 60Hz it will work fine. Contact closing
speed will be slightly slower. Margin will be reduced, but its only
being reduced from enormous to slightly less enormous, so its a non-
issue except in very unusual situations.

Well, high ambient temperature and low input voltage. May not be that
unusual. I've seen it happen more than once, particularly in
industrial situations where ambient temperatures can be relatively
high.

I even had to wire an autotransformer into a domestic elevator control
panel because the designer ignored the necessity of allowing for
voltage drop when the drive motor started, which caused chattering of
the AC contactor even in a climate-controlled 22°C environment.

The vibration tolerance of
the contacts will be little affected in practice; if your environment
is harsh enough to shake the relay contact open, then you've got
bigger worries than contacts crackling.

Since the OP didn't describe the environment.. it may or may not be.
For aircraft work (yes, some is 60Hz) it would be a really good idea
to check. If it's sitting on a subpanel with the control cabinet
bolted to the floor rather than to an OBI punch press, not a big deal.

If instead you meant you would use it on 110v 60Hz, then dont. But you
could use diodes to get a higher dc voltage and use that.


NT


Best regards,
Spehro Pefhany
--
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