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Relay Switching Current vs. Relay Maximum Carrying Current

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danner123

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I understand the following for Relays:

Maximum Switching Current - The maximum current which can safely be switched by the contacts.

Maximum Carrying Current - The maximum current which after closing or prior to opening, the contacts can safely pass without being subject to temperature rise in excess of their design limit, or the design limit of other temperature sensitive components in the relay (coil, springs, insulation, etc.). This value is usually in excess of the maximum switching current.

I am looking at a relay that has maximum switching current = 250mA and maximum carrying current = 1.5A.

If the relay can carry current = 1.5A, why can it only switch current = 250mA? I would assume it could switch 1.5A

Thanks!
 

What is the voltage rating for that relay?

If rated voltage is high combined with inductive load, the manufacturer would probably set that current on order to garantee that the relay will stay good for a minimum number of switches and/or age.
 
Switching and carrying are two different things. Switching relates to its ability to make and break, terminate an arc etc.

Carrying relates to the steady state DC resistance and heat tolerance/dissipation

It can go both ways. I've seen lots of relays that switch more current than they carry.
 
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