Digital Overload Relay Amp Rating

i assume you are in India. Electronic overload relays are available from the following :

Schneider Electric India

ABB India

CS Electric

and a few others too.

The motor current is about 135 A.

Hi kamatchi0515

your motor will draw about 114 A, your overload has to be set at (127 A) as the overload is usually set at "115%-130%" of the rated current of a motor.....this percentage depends on the the motor's power.

I hope this helps

Thanks.

Sorry, but 75000/(√3 x 380) = 114A. There is then the matter of PF and efficiency to be considered, which makes it closer to 135-140A.

As the OP's name seems Indian, i assumed she is from India, and if so, the relay will have to be set to the actual motor current, if it sees the full motor current. If it is used in a star-delta starter, the relay will see In/√3 ≈ 80A. Then there is the matter of whether it is a Class 10A, 10, 20 or 30 starter depending on the starting duration. More info from the OP will help in deciding all these.

If i am wrong in assuming the OP's nationality, location and sex, my apologies

I agree, most solid state overload relays require that the setting be at the motor nameplate FLC, the 115-130% is already factored into their trip curves.

Hello dear,

The answers were already given for your question. This , you need for a project record or actual installation at the site??

If this relay is required for site installation, collect the motor data sheet from the motor manufacturer. Then note the required fields live FLC,starting time etc and forward the details to the Over load relay manufacturers. Specify your requirement for S/C,O/C etc. He will suggest you the required relay.

PRATAP