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Is relay paralel to NTC termistor even worth it?

rjenkinsgb

Well-Known Member
Most Helpful Member
So either that resistance value is wrong, or the relay is badly overrated.
It says 0.1 Ohms when switching 6 volts. That may be "worst case" at a voltage too low to wet the contacts, or an initial figure.
Any decent high current relay should have a contact resistance little more than that of the total metal path through it, a few milliohms at most.

Just looking at the data for a 10A Omron relay we use a lot, that also says 100 mOhm - but there is a footnote to the table saying the data is "Initial values" so I'd say that is after storage and before they have had an adequate wetting voltage applied in use.
 

MacIntoshCZ

Active Member
It does say the contact resistance is 100mΩ, but that would give a contact dissipation of 22.5W at 15A contact current which would fry the relay.
That's why you care about the 0.1R. It has nothing to do with the coil resistance.

So either that resistance value is wrong, or the relay is badly overrated.
What 1A 6V after 100mR actually means? Contact resistance: 100mΩ(1A 6VDC)
EDIT: rjenkinsgb just replied.
 

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