This issue is with a chilled water pump that is controlled by a VFD. The Chilled water pump is 208 3phase 15 hp with a FLA of 37 amps. At 59.5 Hz it is running at 47 amps. I checked the line voltage and it is measuring 205v. The voltage on the load side of the VFD is 199. I would have thought that being that close the the 60 hz that the voltage would be closer to 205. The current reads the same on all legs. The voltage reads the same on all legs. So I don't think we have a phase loss. I would think that there is a problem with the VFD or that there is for some unseen reason too much load on the motor. Does anyone have any Ideas?
Vfd
- Thread starter JdoubleU
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eric9822
Senior Member
- Location
- Camarillo, CA
- Occupation
- Electrical and Instrumentation Tech
How are you reading the current on each leg?
Sounds like the motor is overloaded or the readings are suspect.
An undervoltage of about 3% would not normally result in the motor running at nearly 30% above rated current.
charlietuna
Senior Member
Sounds to me that the pump is too large for the motor. The high amperage is a factor of the work being preformed by the prime mover. Check the pump's spec sheet, the 15HP motor is probably only suitable up to a certain frequency---above that frequency the pump might require a 20 HP motor.
with a clamp meter
ptonsparky
Tom
- Occupation
- EC - retired
Use the display options on your Vfd for motor current while in use. Safer and most likely more accurate then the typical amp clamp.
Cold Fusion
Senior Member
- Location
- way north
Where? On the input to the drive? On the leads to the motor?
Is the motor hot to touch?
cf
eric9822
Senior Member
- Location
- Camarillo, CA
- Occupation
- Electrical and Instrumentation Tech
Unless you have a very good true RMS clamp on meter it will not be accurate. Like ptonsparky says, always go with what the drive display shows.
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