Re: Relay and the surge current

Vladimir Vassilevsky wrote:
Hello All,

I need to run non-repetitive high current pulses (~1kA, ~100us) through the contacts of the conventional electromagnetic relay.

How can I estimate the safe limit (t*I^2 or something else) for the relay contacts?

The contacts are closed during the surge. No switching at that time.

In the datasheets for the relays, they always provide only the maximum current limited by arching when switching.

Can we suggest that a relay rated at 10A, 220V will sustain eventual pulses of 1kA x 100us ?

Any ideas?

try it ?
Are these real pulses, or some Transient theory ?
Measure the contact resistance (eg 5mOhms)
1kA -> 5V -> 5KW, 100us -> 0.5J - then you need to choose what
fraction of a gm of metal that energy is heating, and use the
specific heat, to figure how hot that might get. That's
then just an indicator.
-jg

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