I know that a oversized motor would consume more energy than a well sized one, and in a low load scenario it will present a lower power factor than a well-sized one too. My question is, what is the difference between oversizing a synchronous vs an asynchronous motors? Does this drop in power factor will be for lagging or leading currents for the asynchronous vs synchronous respectively? Also the synchronous motors will behave as capacitors under a light load. But, which drawback could cause this effect in a grid that has more than 8 oversized motors?
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2\$\begingroup\$ You mean "motor", not "engine". In English, "motor" is electric, while "engine" is fuel-powered ((e.g., petrol/gasoline). \$\endgroup\$– Davide AndreaCommented Oct 19, 2021 at 19:35
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\$\begingroup\$ It helps us if you add your location to your user profile as sometimes we can work out the translation funnies. \$\endgroup\$– TransistorCommented Oct 19, 2021 at 19:37
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\$\begingroup\$ sorry for it. I am from latin america and english is not my mother language. I mean a electrical motor \$\endgroup\$– user14398375Commented Oct 19, 2021 at 19:58
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\$\begingroup\$ In a synchronous motor, the power factor can be adjusted by changing the field excitation. To answer the question about effect on the grid, please give an idea of how big the motors are (in kW) \$\endgroup\$– TheodoreCommented Oct 19, 2021 at 20:23
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\$\begingroup\$ there are 5 pumps and 3 compressors, the pumps are of 14 kW, 11kW, 2x(7.35 kW), 5.5 kW and the compressors are 5.5 KW . I know them are oversized because we have a grid analyzer that when all pumps are on just detect an increase of 14 KW instead of ~44kw them should consume in more load scenarios. \$\endgroup\$– user14398375Commented Oct 19, 2021 at 20:37
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1 Answer
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The induction motors will present a lagging power factor. If the motors are oversized, the lagging power factor will be greater.
The power factor of wound-field synchronous motors can be adjusted to be leading or lagging. If the local installation has both induction and synchronous motors, the synchronous motors can be adjusted for leading power factor to compensate for the lagging power factor of the induction motors.
Wound-field synchronous motors are more complex and usually more expensive than induction motors. They are seldom used in ratings in the tens or even hundreds of kWs.
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\$\begingroup\$ so why are them being used in a 15 kw operation, also the load that this synchronous motors are moving is really low. Which effect will cause to the grid or to the motor itself this over-sizing?. Another point to take into account is that there is a explosive atmosphere where the engine operates. \$\endgroup\$ Commented Oct 20, 2021 at 1:59