Looking for a 400 Hz Relay Coil

S

Thread Starter

Seb

I need to find a relay with a coil that can handle 115V/400Hz. Standard 50/60Hz relays don't work properly with the 400Hz. I checked with standard manufacturers (Finder, Omron) but they don't make them. This is for an aviation application where most equipment runs on 115V/400Hz. The contact ratings are not important.

Thanks
 
S

Stephan Poirier

Put a bridge rectifier between your hot line and the neutral then use the output of the bridge (+/-) to connect a 120VDC coil relay. May be you will have to filter the output of the bridge. Hope that it will help you.
Stephan

 
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Johan Bengtsson

That is (of course) because the coil is an inductor and the higher frequency makes the current thru the coil smaller than expected. Here are two possible solutions:

Try to find a coil origianally designed for lower voltage and make sure you get the same current tru the coil. This can be somewhat tricky to caclulate since the current will be a result of both coil resistance and inductance.


The other soulution is to put a rectifyer direclty at the coil and get a relay coil designed for 127VDC (the average voltage after rectifying will be 1.11 times the AC-votage if it is sinus)


/Johan Bengtsson

----------------------------------------
P&L, Innovation in training
Box 252, S-281 23 H{ssleholm SWEDEN
Tel: +46 451 49 460, Fax: +46 451 89 833
E-mail: [email protected]
Internet: http://www.pol.se/
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J

Johan Bengtsson

I forgot to mention one thing, sorry

The insulation of the coil does of course have to accept the higher voltage but the voltage rating of most relay coils is dimensioned around what current is enough to make the relay operate and how much current it can handle before it gets too hot. But you would of course need to ask the manufacturer before you install it in any serious application. I don't think it would be a problem normally.


/Johan Bengtsson

----------------------------------------
P&L, Innovation in training
Box 252, S-281 23 H{ssleholm SWEDEN
Tel: +46 451 49 460, Fax: +46 451 89 833
E-mail: [email protected]
Internet: http://www.pol.se/
----------------------------------------
 
M

Michael Griffin

Johan Bengtsson wrote:
<clip>
>That is (of course) because the coil is an inductor and the
>higher frequency makes the current thru the coil smaller than
>expected. Here are two possible solutions:
<clip>
>The other soulution is to put a rectifyer direclty at the coil and
>get a relay coil designed for 127VDC (the average voltage after
>rectifying will be 1.11 times the AC-votage if it is sinus)
<clip>
This is sometimes referred to as an "economy" DC coil and is
available as an option for at least some relays. We used such a coil in a
project a few years ago because for some reason this version of the special
contactors we used was more readily available than with a plain 120VAC coil.
The rectifier was a small 4 pin package (with spade terminals) which
would screw to the back panel (which acted as a heat sink). The rectifier
was just a standard item we bought from an electronics distributor.


**********************
Michael Griffin
London, Ont. Canada
**********************
 
Just a cautionary comment to advocates of AC to DC operation of a relay:

Typically AC designed coils are furnished with a "shading coil" in the
magnetic structure. It is used to reduce "hum" vibration. Sometimes this
feature will adversely affect the "dropout" voltage of the relay. In the
worst-case scenario residual magnetism will prevent "dropout!" Of
course, a lot depends on physical orientation of the relay.

Regards,
Phil Corso, PE
(Boca Raton, FL)
 
M

McConnell, David P

Regarding the original post:

Try Leach International or any other relay manufacturer that serves the
aircraft industry. Large aircraft (and spacecraft for that matter) utilize
400 hz power. Normally three phase, 120 volt delta.

Dave McConnell
Stennis Space Center
 
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