W=V*A what if V changes?

[half_full]

Hi All, from the product description below I'd like to know if there would be an amperage difference for this product if the input or working voltage is 110ac?
I know Watts = V*A but how does the 40A rating below change if working voltage changes?
Is it correct to say that at 110V and 40A the relay can handle 4400W? I know based on the calculation it seems to be a duh moment. But I hate making assumptions.

Product Description :

Items: Solid State Relay

Model: SSR-40 AA

Input voltage: 80-250VAC

Output voltage: 24-380VAC

Output current: 40A

Working voltage: 250V

 

[sublimate]

It can handle that 40A current at any of the voltages listed (even 380v), so no issue at 110v (or more likely 120v).

 

[404]

Hi,

That calculated wattage does not apply to the relay or any switch.

When the relay is on, it has a very low resistance, and the wattage dissipated would be calculated as I^2 * R, where R is the on resistance of the relay and I is the current through it.

The voltage is relevant when the relay is turned off.

The 40 does not go up at 110 volts. The 40 amps is the max rated, and in a real design it need to be de-rated for reliability. Perhaps de rate to 30 amps in use. The relay probably needs to be attached to a heat sink with air going over it.

Hoped that answered your question.

Regards,
404

 

[miner]

What they said. Amperage is usually the main thing you worry about in terms of sizing relays and switches. Most devices have the same amperage rating at varying voltages.

 

[404]

Just to add, if the load is inductive, or the current is DC instead of AC, there will be more wear or stress on the switch when the load is to be turned off.