Motor protection example

Assume you have a motor rated 500 HP, .95 power factor & 90 % efficiency energized from a 4.16 Kv source, using a microprocessor motor protection relay, provide the typical settings.

The full load current can be taken from the motor nameplate as well as the service factor. The motor full load current can be calculated from the following: I = 500 (.746)/1.732 (4.16)(.85)(.9) =60 amps.

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