Dear team, Could you help to int

[Dhruv B Patel]

Dear team,

Could you help to interpret this Motor Nameplate data?

The main interest is to interpret the locked rotor current and safe stall time. The Rotor Code is S and V:1090, A:265.

Is 265 A (500% of Rated current 52A) locked rotor current? What is the standard hot-locked rotor time for the below motor?

Many thanks

Regards,
Dhruv

 

[edison123]

It's a slipring motor.

1090 V is rotor open circuit voltage and 265 A is rotor full load current at rated speed.

Locked rotor currents are not published in the motor nameplates. They will be in spec sheets.

Muthu

http://www.edison.co.in

 

[Gr8blu]

Beat me to it. Agreed - the nameplate refers to a wound rotor induction motor (rotor separately powered through brush-and-collector assembly). Rotor open circuit voltage is 1090 Vac. Rotor current at rated load and speed is 265 Aac.

Converting energy to motion for more than half a century

 

[che12345]

Mr Dhruv B Patel (Electrical)(OP)5 Apr 23 11:12
#204A87]" #1. ....Could you help to interpret this Motor Nameplate data?....#2. The main interest is to interpret the locked rotor current and safe stall time. The Rotor Code is S and V:1090, A:265...."

1. Your question had been fully answered by our learned contributors. Take note that it is a Slip-ring or wound rotor motor. It is Not a squirrel-cage motor.
2. For a slip-ring motor, it is always start with the maximum external resistance. The value of the full resistance is designed to limit the starting (stator) current; usually < 2.5 times the stator full-load current. It is possible to vary the starting current by the resistance. This external resistance is usually shorted out when the motor has attained the final running speed. Some applications may required a small resistance value to remain in the rotor circuit during running.
2.1 The safe stall time is dependent on the starting current, which is dependent on the external starting resistance. It differs from that of a squirrel-cage motor, with starting current usually > 6 times the full-load rated current, with DOL starting.
Che Kuan Yau (Singapore)

 

[Dhruv B Patel]

Thanks all for the above guidance.

Further, the main task is to determine the protection settings of this motor (480 kW,6.6 kV,0.85 PF, 52A: no other data available). Below is the previously installed P&B gold relay which will be replaced by a newer 859 relay.

Could you assist me to interpret this P&B Gold setting? Overload, Instantaneous, Earth

Many thanks
Dhruv,

 

[edison123]

125% of stator current is the OL limit but setting it depends on your relay.

If your relay has the 125% OL setting built in, you must set the overload protection at the motor’s nameplate current (i.e. at 100% rated current). If you set this relay at 125%, then the actual overload protection will be 156%, which exceeds the limit.

If the 125% value is not built into the relay, you must set it at the motor’s nameplate current + 25% (i.e. 125%).

Muthu

http://www.edison.co.in

 

[Dhruv B Patel]

As data is not available for this old motor, the Worst case service factor is 1.

Does 100% OL settings(52A)a good choice?

How Acceleration settings (GE 859 Relay) of the motor is determined?

Thanks.