Following on from the Automotive Relay thread;
What are the reasons behind the apparent fact that relays last longest in this order of coil protection:
(No protection being the relay lasts longest, the standard diode being the worst thing for the relay - forget the circuit protection issues just now)
From this data - scroll to the bottom for a chart:
Cheers,
Gareth.
Arcing on opening.
Fastest opening. Less damage to contacts.
If indeed your order is correct, Slow opening.
Slower Opening.
Slowest Opening. Most damage to contacts.
This is very interesting, it raises points I had never considered such as the momentary current flow through the diode and coil, and how that can stress other parts. The two articles are good reading!
It explains why (in my field of pinball repair) manufacturers stopped putting suppression diodes on the coils and instead put them in place to protect the driver devices (transistors/Mosfets, etc.).
Thanks for bringing this topic up!
Do note that both articles say you HAVE to protect the driver device from the back EMF!!
John :-#)#
Thanks for that link. Interesting indeed.
Gareth.
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