Older 3 Phase Toshiba Drive Question

Is the motor vector duty? Does make a diff on these units.

The motor is a continuous duty motor . Thanks for the response .

The overloads are doing their job. What is needed is to determine the cause of high current, at least, current enough to cause the trips to operate. Is the pump mashing something friable when it turns, for example, at low speed, and passing it without damage at higher speed?

Double-check that the inverter overload trip settings are the same as those on the motor nameplate and have another go.

If all else fails, change the motor for the stock spare, and re-order.

Hey Slack .

It is the heater OL's on the contactor that are tripping and not the drive OL . The pump pumps a gel-based concoction . Thanks for your response .

Hi:

All inverters tend to drain higher amps at the load when ran at low speeds, if you decouple the gear transmision, that will make the problem worse, because you'll have to reduce the drive's frequency output by as many times as the transmision ratio.

I'd recomend to check all motor wires are the same lenght and caliber.

Also you should tune the drive parameters to your motor's characterictics i.e.:

Motor rated Amps. (FLA), motor number of poles (or rated RPM), rated voltage and base freq. of the motor; and if the problem continues, you should select and try different carrier frequencies, to get the best performance and less noise from your motor.

If nothing of this helps, I would suspect the drive, get a loaner with a friend and give it a try, that will clear any doubts.

Regards

Thanks Yahlasit .

Everything checks out that you mentioned . The problem just started happening and the drive setting were never touched .

Get a GA from me , Sir. you go straight to the problem, but still wish my advice be taken as a common good practice to be observed always when working with inverters.

Regards

JRaef .

Your response was extremely helpful . You sound very convincing that it is the drive , something I suspected all along but could not make a logical decision . My only problem now is that I only have Allen-Bradley Power Flex drives to replace it with so I'll need to change some control wiring around . I knew the imbalance was a problem but could not understand why it was happening . Thanks .

The "volts-per-hertz" ratio of the VFD could be off but normally this fault would be reflected in all three phases. (Usually drive control board component failure)

Have you checked and verified that the impedance of the motor windings are balanced? (A-B, B-C, C-A)

Is the applied voltage to each phase balanced? (Phase to phase and phase to ground)

If all of the motor characteristics are balanced, the drive would be suspect.

If the applied voltage magnitude and frequency is balanced, the motor would be suspect.

If these simple tests do not reveal the root-cause of the issue, attach an oscilliscope to the motor leads, capture waveforms form each lead combination, and compare/analyze to identify the failure.

Look to me the VFD need to repair or change.

What pump application it is ? Water pump, Hydraulic pump or ....?

Old type VFD sometime difficult to find. PM me if you need reference for replacing.

Thanks Romeo .

Replaced the drive last night with a brand new Allen-bradley Power Flex 40 . Had an electrical engineer make up a print and the conversion went smoothly . The phase imbalance is gone .