Rating of the Relay

[Sravanthi]

Hi...

Is there any dis advantage of selecting a electromagnetic relay which is having higher contact rating of our application.

Suppose if I my application needs 1A current carrying contact , if I am selecting 16A contact rated relay. Does is there any disadvantage.
Please reply me..

Thank you.

 

[(*steve*)]

it might cost more

the coil may require a higher current

it may be larger

for very low current applications (lower than you're talking about) you may not have sufficient current to wet the contacts.

 

[Sravanthi]

it might cost more

the coil may require a higher current

it may be larger

for very low current applications (lower than you're talking about) you may not have sufficient current to wet the contacts.

Can you explain last point: very low current applications (lower than you're talking about) you may not have sufficient current to wet the contacts.
Related to failure rate of the relay will there be any change.

 

[AnalogKid]

For some applications such as AC power to motors, the contacts arc as they separate. This arc burns off oxidation that would eventually form an insulating barrier over the contacts. Depending on the contact material, there can be a similar issue with low current DC signals. This is why many panel switches are available with silver contacts for 10 A AC, or gold contacts for 0.1 A DC. Of course the actual ratings vary from one manufacturer to the next, but those are the basics.

ak

 

[Sravanthi]

For some applications such as AC power to motors, the contacts arc as they separate. This arc burns off oxidation that would eventually form an insulating barrier over the contacts. Depending on the contact material, there can be a similar issue with low current DC signals. This is why many panel switches are available with silver contacts for 10 A AC, or gold contacts for 0.1 A DC. Of course the actual ratings vary from one manufacturer to the next, but those are the basics.

ak

Thank you for basic information.
What is the dis advantage of using a higher rated contact for low current application. Its a DC contact relay.
Can you give me the basic of bifurcated contacts. Is DPDT and bifurcated contacts are same???

 

[(*steve*)]

Why do you want to know this. It's starting to sound like homework.

Also, simply googling "wetting contacts" would have given you multiple links to you previous question.

Have you tried google for your questions?