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Variable frequency drive in HVAC

I am not much experienced in the HVAC thing but trying to gain some expertise over VFD's.
Please let me know the functionality and need of the following:

1. Ground Bearing protection
2. OL contactors
3. Run Contacts.
4. KAIC ratings
5. Bypass requirement and fused disconnect vs Circuit breaker.
6. Test Feature in VFD.
7. Seismic Testing
8. Motor adaptation Test algorithm
9. Difference between Galvanic and Optical Isolation
10. Class 20 I2t (Its I square T) electronic motor overload protection
11. Run permissive in bypass

I know its too many questions here but I need some clear focus on VFDs.

1. Sometimes the carrier frequency can cause unwanted currents in the motor rotor which bleed out through the motor bearings causing pitting and bearing failure. Mostly in centrifugal pumps so usually only a problem with chilled water systems in HVAC.
2. A relay or contact that triggers when an overload occurs.
3. Could be an input to start the drive or an output to know the drive is in RUN mode.
4. The ability of a protective device, fuse, CB, to interrupt a dead short in k/1000s of amps. This is more a electrical code issue and varies from place to place.
5. If the drive fails or trips do you want to be able to bypass to a motor starter and run full speed until the drive is fixed. Or maybe switch to another drive? When a fuse blows you by another, when a breaker trips to reset it.
6. Worthless.
7. If the building is shaking enough to vibrate the components off the circuit board you won't care.
8. As a rule not needed for HVAC. This fine tunes the drive to motor for high performance applications. HVAC is usually easy start with slow speed changes.
9. Exactly what type of galvanic isolation?

Never ran into a need to run a drive when it is bypassed. I guess you could do a hot switch and have the drive frequency match on a large blower motor.

Contact the local variable frequency drive distributors and see if there are any classes on VFDs you can attend. These are periodically given by there various manufacturers to promote the use of their brand. If you have a particular application the distributor may show you how to do it with their brand of drive. You can also go on various manufacturer web sites and go through the technical support library.

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