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Subject: Re: A couple Tyco papers on emf reduction in relays
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From: Colyn Case <colyncase@earthlink.net>
In-Reply-To: <5294D189.6010105@comporium.net>
Date: Tue, 26 Nov 2013 12:37:01 -0500
Cc: lml@lancaironline.net
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References: <5294D189.6010105@comporium.net>
To: John Cooper <snopercod@comporium.net>

Well, they were talking about protecting the contacts of the switch that =
controls the coil, and how some methods of doing that decrease the speed =
of opening, which is bad for the relay contacts.

I'm not sure you will really see the inrush current with the shunt.  Too =
slow.

Buy really good relays...

On Nov 26, 2013, at 11:51 AM, John Cooper wrote:

Colyn--

Those Tyco links were excellent, thanks. Let's keep in mind, though, =
that Tyco was discussing the possible adverse effects of surge =
protection across the relay coils, not the contacts. Based upon the =
information in those articles I'm going to remove the small ZNRs I =
installed across my hydraulic relay coils to protect the landing gear =
switch contacts. Perhaps I'll replace them with those Snapjacks (Thanks =
for that link as well.) I plan to leave the large ZNRs in placed across =
the hydraulic relay contacts.

Those Tyco articles may be of special interest to Adam since his Bosch 0 =
332 002 156 hydraulic relays have the built-in diode protection across =
the coils. Also, the second article discussed how excessive inrush can =
cause relay failure.

FWIW, I ordered a 60A shunt which will (hopefully) allow me to measure =
the inrush current on the Oildyne pump motor. I'll report back if I =
learn anything.