Delta motor, wye power

Stupid question.

I have a motor that is Y-start Delta run, but I plan to start it direct-on-line (motor documentation says this is acceptable)

There is no issue with the fact that the plant's power source is wye, correct?

Wye systems can feed a delta load such as a motor just by eliminating the ground connection, correct?

Are there any issues with using a circuit breaker, such as the 140M series?

Whether a motor can be started directly or not depends more on the load it carries than on what the motor specifications say.
If the load has a lot of inertia, for example a turbine of a large diameter fan, it is better or mandatory to use a start-delta or electronic starter.

Any three-phase power supply can be used as long as the voltage matches the motor specifications. If there is a neutral cable (not ground) it will not be used.

You can use any circuit breaker as long as in its specifications it says that it is suitable for the motor.

Rson said:

Stupid question.

I have a motor that is Y-start Delta run, but I plan to start it direct-on-line (motor documentation says this is acceptable)

There is no issue with the fact that the plant's power source is wye, correct?

Wye systems can feed a delta load such as a motor just by eliminating the ground connection, correct?

Are there any issues with using a circuit breaker, such as the 140M series?

Click to expand...

You should be fine, the wye/delta is how the motor is wound and the relation between the poles - the plant power won't matter as long as it's the correct voltage for the motor windings. If it's a large starting load though, you should probably use the start winding.

A 140M would work well, just remember you'll get a larger starting current if you don't use the start winding so you may have to increase the trip value.

To amplify gothroach's reply , the stating current for star/delta is approx. 2.5 times motor FLA . For direct - on - line that increases to 6.5 to 7.5 x FLA . ie a motor with 40A fla will draw a peak of about 100A in star/delta and about 280A peak direct . If you do have a large motor , you should also check the supply can handle this surge .

Rson said:

Stupid question.

I have a motor that is Y-start Delta run, but I plan to start it direct-on-line (motor documentation says this is acceptable)

There is no issue with the fact that the plant's power source is wye, correct?

Click to expand...

Correct. No issue because there is relationship top the source configuration and the motor configuration, other than the voltage being the same.

Wye systems can feed a delta load such as a motor just by eliminating the ground connection, correct?

Click to expand...

Yes, Wye systems can feed a Delta load, but NO, it has nothing to do with connecting or not connecting a ground. ALWAYS connect the ground. All the motor cares about is whether the Line to Line voltage is correct for the way it is configured.

Are there any issues with using a circuit breaker, such as the 140M series?

Click to expand...

A 140M is UL listed as a manual motor starter, if that's the issue you are asking about. Generally, most people use them just as the PROTECTION for the motor and use a contactor to start and stop it, but yes, it CAN be used as the starter too.