[TR] Triumphs Digest, Vol 15, Issue 93

[Anthony Rhodes]

Ronald,

The suggestion to place a diode across the relay solenoid is very useful. However, the actual contact of the relay are electrically separate from the solenoid.

The OP did not state in what manner The relays fell. Does the solenoid stop working? Do the contacts stop conducting or fuse together?

I have not had many relays fail. Usually it’s the contacts that fail. And that is usually due to high current demand across the contacts.

There are 40 amp rated relays that are physically identical or extremely similar to the standard 30 amp relays.  One of those might be worth a try.

You can get relay sockets that have the diode built in, by the way. With the diode, you need to be extremely mindful of polarity! By that I mean that the solenoid now has a positive and negative terminal.

It certainly would not be harmful to have a diode across the relay contacts as well. Switching and inductive load can cause arcing across the contacts similar to what is found in ignition points.

Electric fan motors can certainly be an inductive load!

-Tony 



> Message: 2
> Date: Thu, 16 Jun 2022 13:02:30 -0400 (EDT)
> From: ronald.olds at mchsi.com
> To: keithstewart at bell.net
> Cc: triumphs at autox.team.net
> Subject: Re: [TR] Electric Fan Relay
> Message-ID:
> 
> Keith, 
> 
> I would recommend connecting a 1N4004 diode across the positive an the ground terminals of the relay coil. Connect the cathode end of the diode to the positive terminal and the anode end (the end of the diode with the line om it) to the negative terminal. this will have no effect when the relay is energized. When a relay is denergized it generates a spark which can burn the points. The diode will allow this spark to travel through the diode and dissipate. 
> Connect to relay negative connection. Connect to the relay positive terminal. 
> 
> Diodes should be across the terminals of all relays and solenoids. 
> 
> Ronald Olds 
>