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Synchronous motor FLA

Synchronous motor FLA

Synchronous motor FLA

If a synchronous motor FLA is given at 1.0 power factor, does that go up if the motor is run in the lead (-0.8 p.f.)?

RE: Synchronous motor FLA

No. I2R is not subject to power factor. The current will heat the windings the same amount regardless of the phase relationship between the voltage and the current.
The maximum Amps is determined by the heating effect of the stator current on the stator.
If you wish to run the motor at other than unity power factor then you must reduce the load on the motor.
A synchronous condenser is a special synchronous motor with no load and no provision to drive a load. The current is almost purely reactive.
On the other hand;
If the motor is fully loaded and the PF is changed from unity to 0.8 (+ or -) the stator winding will be overloaded.
Do not exceed the FLA.

"Why not the best?"
Jimmy Carter

RE: Synchronous motor FLA

thank you

RE: Synchronous motor FLA

To expand a little on waross' reply. It is usual to specify a synchronous motor to be designed for operation at unity power factor. This generally gives the smallest cheapest motor and the most efficient. This is because it has the least copper and least iron.

If you specify one at 0.8 pf, say, then it will run with higher losses than the smaller one. Thi s can cost a fortune over the life of the motor, but its power factor correction abilities could
Offset this.

Current is current, the stator conductors and the cables and the switchgear do not care about power factor.

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