Relay contact rating

[karkip]

I came across Two relays with same contact rating 220VAC/10AMP. But one of them is approx 5 times bigger in size than another.
What is the difference in application, when the contact ratings are same ?
How should i select a relay out of them ?
Another thing, Since the voltage specified is 220vac, if sometimes there happens to be a voltage 280-290vac, will the contacts blown ??

 

[KlausST]

Hi,

What is the difference in application, when the contact ratings are same ?

How can we know without seeing the details?

Another thing, Since the voltage specified is 220vac, if sometimes there happens to be a voltage 280-290vac, will the contacts blown ??

Generally speaking.. If you knowingly use a relay (or any other device) beyond specifications than you are reliable for the result.
It´s not very likely, but if there something catches fire .... then you have to open your wallet ;-)

Klaus

 

[karkip]

1. Omron Power relay G4A 39067481 2. G2RL-1A-E2-CV-HA DC12​ both are from omron. the first one is bigger relay,with rating 250vac/20amp second one is other relay, rating 250vac/23amp. Why with almost same rating, the size is comparably different. Will both be able to perform same, if used for switching an equal load ?

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[barry]

The G4A number looks wrong, I can’t find it. Can you post data sheets?

 

[karkip]

Datasheet G4A 39067481

 

[barry]

Theyre nearly identical in size: 29 x 12.7 x 15.7 vs 30.5 x 16 x 23.5. One is rated for 400 VAC, the other 240V. One is rated for DC switching, the other is not.

 

[karkip]

second relay dimensions are 30.5x16x33. and have bigger contact terminal pins , which i assume will be more helpful for high current.
I doubt the second relay part number though, didnt have exact part number . have to go to workplace to find it.
But still my question is same.
i have size constarints on pcb. And both above relay can switch AC loads 230v, which is the desired load. AC Resistive load 200-700watts.
How should i choose between above those. will both be able to switch loads 230vac/20amp continuously?

 

[barry]

If I use my reading skills, and I trust the specs, I would see that they are both capable of carrying 20 Amps @ 240VAC.

 

[KlausST]

Hi,

yes. But the one is more for "ohmic signals", while the other is more rugged for motors and other power applications.

The power one has more magnetic power, this means, when combined with a bigger spring it has more force to close as well as to opan (a slightly welded) contact.

I guess even the contact itself is bigger.

***
Maybe it´s possible to open a faulty relay to get more information about the fault reason.

Klaus

 

[karkip]

Looking at the contact terminals of

G2RL-1A-E2-CV-HA DC12,​

I doubt it can carry continuous current if 20amp @240vac

If I use my reading skills, and I trust the specs, I would see that they are both capable of carrying 20 Amps @ 240VAC

--- Updated Apr 3, 2022 ---

G

Hi,

yes. But the one is more for "ohmic signals", while the other is more rugged for motors and other power applications.

The power one has more magnetic power, this means, when combined with a bigger spring it has more force to close as well as to opan (a slightly welded) contact.

I guess even the contact itself is bigger.

***
Maybe it´s possible to open a faulty relay to get more information about the fault reason.

Klaus

The bigger one relay has never failed . But to save space, looking to replace it with the smaller one. Was trying to understand what parameters should be compared in datasheet for replacement. But due to contact size, it became suspicious .
Switching load is heater and geysers .

 

[barry]

Geysers?

 

[FvM]

Water heaters, I presume. Referring to the datasheets, both relays are equally suited to switch resistive load up to 20A 250VAC. Additional motor load specifications for the G4A suggests that it is more robust. You should also consider that both datasheets specify minimal 100000 switching cycles at 20A, but you don't know about typical endurance. Hence, although G2RL obviously fulfills your specification, it may be the inferior choice though.

Possible steps to assess relay performance in your specific application could be:
Determine required switching cycles during product lifetime, perform extended lifetime tests, measure relay overtemperature (case, terminals) for both types.