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Anonymous Poster #1

Running Lift Motor With Blower Duty VFD

01/07/2020 1:32 PM

I have a lift of 6 ton capacity. It runs in a three storied godown with each floor 7 mtr in height. It is run by a squirrel cage induction motor of 37kW, 415VAC, 3 phase 50Hz. The motor is driven by ABB acs850 lift duty VFD. Now after the said VFD gets damaged, I replaced the VFD with an identical rated VFD. But this new VFD is of blower Application and without regenerative braking feature. Now the lift works perfectly downwards but can't perform slow speed function at all and stop function is uncontrollable in upward direction. Output speed is getting much more than reference speed during stopping. The higher the lift from the ground, the more the problem becomes. I have enabled dc overvoltage control and disabled brake chopper function to avoid bc fault and dc overvoltage fault.

Is there something that I can do to use this VFD to run the lift?

Thanks.
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SolarEagle
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#1

Re: Running Lift Motor With Blower Duty VFD

01/07/2020 6:48 PM

Maybe you can scavenge some parts from the old VFD....

https://www.machinedesign.com/motors-drives/article/21833844/how-to-choose-the-right-control-method-for-vfds

https://www.invertekdrives.com/variable-frequency-drives/optidrive-elevator/

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SolarEagle
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#2
In reply to #1

Re: Running Lift Motor With Blower Duty VFD

01/07/2020 7:25 PM

Came across this, not really related to this OP but thought it was cool anyway, so this guy built a little vfd to speed up his little motor for his desoldering gun....

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JRaef
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#3

Re: Running Lift Motor With Blower Duty VFD

01/07/2020 8:23 PM

If what you had before was a drive capable of regenerative braking sized for a constant torque application like this and you replaced it with one not capable of regen and sized for variable torque, it is never going to work for you.

It’s as if your truck died and you replaced it with a scooter and you want to know how to make your scooter carry a large load of bricks...

Find a pump or fan to use that drive on and get the proper replacement.

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Oomborrie
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#4

Re: Running Lift Motor With Blower Duty VFD

01/08/2020 3:16 AM

Fire who ever advised you. How did you get it so totally wrong. Hope you got the blower VFD as a present and did not pay for it.

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HiTekRedNek
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#5

Re: Running Lift Motor With Blower Duty VFD

01/08/2020 8:21 AM

I do not know your location,but many states in the USA have very strict rules regarding elevators and lifts of any kind.No modifications are allowed for safety reasons.You may be in violation ,so check with local authorities for advice.

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Davehd2009
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#6

Re: Running Lift Motor With Blower Duty VFD

01/08/2020 8:54 AM

Why do you think that they bother to rate the motors with different duty cycles? That said, is it a cable winch lift or hydraulic? If cable, the reason it has more problems the higher it goes is because as the cable winds on the spool the effective radius of the spool grows and it requires more torque to turn. The blower duty motor doesn't have the start-up torque or low-speed torque that the lift rated motor does, which is also why it can't perform the slow speed function. And OF COURSE it does okay lowering, it does not need any power to do that. Somebody's gonna die if it's used for people, or at least the motor's gonna fail. Dumb stunt!!! Whoever's responsible needs to get their resume in order.....
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rwilliams
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#7
In reply to #6

Re: Running Lift Motor With Blower Duty VFD

01/08/2020 10:42 AM

The VFD was changed, not the motor
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rwilliams
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#8

Re: Running Lift Motor With Blower Duty VFD

01/08/2020 10:50 AM

You might be able to limp along by adding a suitably sized dynamic brake resistor, and re-enable your dc bus voltage controls.

I assume you are running it in Sensorless vector mode, I assume your motor has a mechanical brake as well. You might experiment with Volts/Hertz, if the Sensorless Vector control seems to be unstable.
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Anonymous Poster #1
#9

Re: Running Lift Motor With Blower Duty VFD

01/08/2020 11:18 AM

Thanks all for sharing knowledge. The problem is solved by changing the stop function from ramping to coasting. Now it is working as desired. Though I am still little concerned about whether it will harm the motor and the VFD in the long run. DC bus voltage exceeding 650V in upwards movement but not tripping in fault. I also had to decrease the full speed reference from 750 RPM to 500 RPM. Slow speed reference is 250 RPM.

And one thing, the is only for Goods not humans.

Thanks.
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PWSlack
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#10
In reply to #9

Re: Running Lift Motor With Blower Duty VFD

01/08/2020 11:44 AM

It sounds now as though the thread has become a waste of effort.

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rwilliams
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#11
In reply to #9

Re: Running Lift Motor With Blower Duty VFD

01/08/2020 5:23 PM

The VFD will protect itself, and your motor was already used to seeing PWM, so it should also be fine. The VFD may not have an extraordinary service life, granted.

It doesn't make sense that your dc voltage would go up (overshoot?) for upwards movement, downward would make more sense. Your braking resistor, if you have one, would be more taxed for downward movement, esp. if loaded
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PWSlack
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#12

Re: Running Lift Motor With Blower Duty VFD

01/09/2020 8:29 AM

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Anonymous Poster (1); Davehd2009 (1); HiTekRedNek (1); JRaef (1); Oomborrie (1); PWSlack (2); rwilliams (3); SolarEagle (2)

Previous in Forum: Solid State Voltage Regulator to Replace Mechanical Type   Next in Forum: Weird Electric Motor Behavior

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