Im looking for some opinions and perspectives - I'm a mechatronic instructor at a community college. I'm not a motor expert but I'm starting to learn more about it.
Can I ask the group a question - is power factor, corrective capacitors to minimize reactive power, apparent power - is this stuff critical for a mechatronic technician? Its kind of blowing the heads of my students unfortunately.
Also - do they need to understand how every single type of AC motor works in detail?
I could be very wrong but it seems like capacitor start induction motor and 3 phase motors are the main ones out there?
Thank you for any advice. Hope everyone is keeping safe....
Tim
The utility must supply kVA to make sure everyone gets enough. But users are billed for kWh, and the difference between kVA and kW is power factor (W = V X A x PF). So the lower your PF is, the less KWh you pay for. But the UTILITY still has to deliver you the full kVA, so if your PF is low, they penalize you with a multiplier on your power bill. You can correct PF at the loads by adding PFC capacitors. But also understand that VFDs also correct the PF as seen by the distribution system, so PF of the motor becomes irrelevant if it is being run by a VFD.
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Originally posted by daba:
How will they know you are using PF correction ?
How will they know you are using PF correction ?
Saw your response too late...That's the beauty of it. They don't care. You are paying for the effects of the actual displacement power factor, not whether or not you are trying to do something about it. Whether the money you spent to TRY and better your power factor is actually bearing fruit is immaterial as far as the power company is concerned.
On a tangentially related note, I once had a customer who specified active front end drive systems because his power company was beating him up over harmonic power factor. While AC drives will generally not create an issue with displacement power factor they can be a beast in terms of harmonic power factor. An AFE will usually do pretty well in terms of harmonic power factor, maintaining the fidelity of the AC current waveform entering the system. I'm still not 100% convinced these things paid for themselves but the customer said they did.
Keith