I have a motor overload relay attached to a motor which is connected to a pump. The relay is set for 10 A. But when the current supply to the relay is 8 A, it trips. I have checked the current supply using a clamp meter.
Its a 3 phase 5 hp motor. The relay I am using is from Schneider Electric.
i think, some problem is in relay coil,
On 8A your relay coil produces that much sufficient attractive force so that, relay produces trip signal..
My suggestion is remove relay from circuit, and check separately that " your relay is producing trip signal at what amount of current" ..
Hi Nishant - Thanks for your input - Could you please tell me with which instrument we can find the trip signal current
@hakeem
which type of Relay you are using. ?
i mean Electromagnetic relay NO or NC type.
or any thing als. ?
please give this information so i can help further ...
Most possibly your meter shows estimated reading. Please check the actual current. Moreover, check relay settings.
Try using a different meter to see if you will obtain the same result. The meter could be faulty. Also, check for harmonic content in the signal supplied to the relay.
some motors have starting current greater than 7 times of full load current. Could this large starting current may effect the relays operating.
Thanks to all for the inputs - While analyzing the issue - we come to know that it was completely a different problem - The pump's bearing/gear oil is almost nil - because of this overload problem arose - Solved by filling the proper oil.
Its a good experience and provide us the knowledge of impact analysis.
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