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Why do relays struggle to switch high voltage low current loads?

Braeden Hamson

Feb 18, 2016
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I'm reading through this datasheet:

https://www.mouser.com/datasheet/2/307/en-g7l_x-1061788.pdf

On page 5 it talks about microloads:

These Power Relays are suitable for switching and breaking high-capacity DC. At high-voltage and low-current, breaking characteristics may become unstable. For 1A or lower switching applications please contact us.

Why would a relay have issues at low current as opposed to high current?
 

Minder

Apr 24, 2015
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Search for relay wetting current, the lowest current before the contact becomes unstable.
 

Braeden Hamson

Feb 18, 2016
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So, its the minimum amount of current needed to break through the oxide layers on the contacts such that they actually contact?
 

Harald Kapp

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Nov 17, 2011
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For low currents do not use power relays, use signal relays with gold plated contacts. Gold prevents oxidation. Or in extreme cases use relays with mercury wetted contacts, but mercury is a hazardous material, use only as a very last resort - if today you can buy them at all .
 
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