Relay Rating

They could be, though they need not. On the shelf here is a 24VDC relay with a 250VAC 5A contact rating, for example. Nearby is a 240VAC relay with a 240VAC 10A contact rating.

No need means, Why we are having same rating for both? What is the use? Ca u tell me about Coil & Contact rating briefly. Important points..

It's all to do with the mechanical construction of the device. In general terms, the smaller the contacts are dimensionally, the lower the rating. The smaller they are, though, the more of them one can get into any defined volume.

Have a look in the RS catalogue (usual disclaimer) for some examples.

Here's what Wiki has.

There was one application where the answer to your question is a resounding YES!!!!

Years ago I was working on some signalling relays with VERY long connections. (Like railway distances) The relays were used to receive and "sharpen" the signal to be relayed further through the system.

These "relays" were located at about the 25% voltage drop distance along the lines.

They were called relays since their purpose in life was to "relay the signal."

Please note that coils are always rated with Volatge & VA and contacts are always rated with current. May be, contact current rating will be given at a certain voltage, say, 5A at 240V AC or 1A at 110V DC, etc.

contact rating are in Amper! example-10A

The contact voltage =the contact will not arc and you r not allow to use voltage less than 25 V!!