Thread: More VSD/VFD problems.

Originally Posted by Ironwood

Just checked Cliff, 242 volts at the VSD terminals while the motor is running at a slow speed....

OK, cross that one off the list.

i had a similar problem using an elcheapo chinese vfd if you set the motor amps at what the name plate( 1 .4 amps) said it would cut out with just a light cut .some where i read you should raise the motor current to a higher value which i did (5amps)and it fixed the problem .A very heavy cut only brings the current up to about 4.4 amps. it doesnt seem to have had any bad effects on the motor or vfd nothing gets overly warm
john
hmm i wonder if wired in delta config the amps should read 3 times the rated in star mode( 3x1.4=4.2)

Originally Posted by azzrock

your probably right. had not thought of it like that. what about the machine the motor is running at twice the speed. probably ok for a short time as well.
do you loose much torque at over 50hz

My lathe has a tapered roller bearing headstock, I am pretty sure it can run at high speeds for long periods of time.
I guess you will have to make a call on your own machine, taking its design and condition into mind.

I am not expecting to lose much torque at the Hz range I have set on the VFD.
My VFD has vector control so I am hoping for good torque through a wide Hz range.
From what I have read, I will lose torque at very low Hz, and also very high Hz.

Originally Posted by Cliff Rogers

Power = Voltage x Current

Power/Voltage = Current

actually there's a power factor correction in there as well, which for a motor running outside it's nameplate range could be quite low.

If the motor is working at a power factor of less than about 0.7, a 1.1kW motor will overload a 1.5kW supply.

3.2amp no load seems too high

How did you measure the voltage at motor terminals?...to terminal-earth or across each phase?

did you measure all three phase current draws?

Have you put a megger on the motor to ensure it doesnt have any leakage to earth?

(I assume your using a 240 single phase to 240v - 3 phase vsd.)

Originally Posted by RayG

Just as an experiment, you could drop F009 back to 3% and switch back to V/F mode (F067=1) and see if the current goes back to what you were seeing originally.

But, switching back to V/F mode, that's not really using the drive to it's potential.

Regards
Ray

Checked the F009, it was set on 5. Set it back to 3, and ran the motor, it was an improvement, but still cut out on OL. I changed it back to 2, still cut out on OL when running at high speed.

I changed back to V/F mode, that didnt seem to change the current at all, it still cut out on OL.

I checked F068 ( vector voltage compensation) it has been set at 5 by the autotuning.


F084 (power supply voltage) is factory set at 220 , I had never changed this before, but I set it to 240 today.
This didnt seem to improve things.

Originally Posted by tanii51

i had a similar problem using an elcheapo chinese vfd if you set the motor amps at what the name plate( 1 .4 amps) said it would cut out with just a light cut .some where i read you should raise the motor current to a higher value which i did (5amps)and it fixed the problem .A very heavy cut only brings the current up to about 4.4 amps. it doesnt seem to have had any bad effects on the motor or vfd nothing gets overly warm
john
hmm i wonder if wired in delta config the amps should read 3 times the rated in star mode( 3x1.4=4.2)

I might have to try this also, before I did the autotuning, the problem wasnt evident.

Originally Posted by eskimo

3.2amp no load seems too high

How did you measure the voltage at motor terminals?...to terminal-earth or across each phase?

My Lecky mate was doing the testing while I operated the VSD, so I am not sure, but will check with him.

Originally Posted by eskimo

did you measure all three phase current draws?

I remember him mentioning that all 3 phases were high, so I think he must have.

Originally Posted by eskimo

Have you put a megger on the motor to ensure it doesnt have any leakage to earth?

(I assume your using a 240 single phase to 240v - 3 phase vsd.)

A different Lecky mate tested the motor with his megger before I fitted it to the lathe. He said it was all good.

The VSD is single phase to 220/240 3 phase. It was factory set at 220V supply, I changed it to 240V today.

Hi Ironwood,

Not sure how easy it's going to be to try and figure out what the auto-tuning function has changed.

Just checking...what values are entered for the number of poles F52, and of course.. the ratio of inverter rated current to motor rated current F78.

Also while we are digging around, if you have time while dodging march flies..

F1: acceleration time
F2: deceleration time
F10: rated frequency of motor (factory setting: 50Hz)
F15 upper limit frequency

F11 rated voltage % of motor

F67: Operation Mode
F68: vector voltage compensation
F69: Slip compensation



If all else fails... the next step...

It's a drastic step, but it might be quicker to just reset the drive to factory defaults and re-commission it with the settings you originally entered.


Regards
Ray

Originally Posted by Ironwood

My lathe has a tapered roller bearing headstock, I am pretty sure it can run at high speeds for long periods of time.
I guess you will have to make a call on your own machine, taking its design and condition into mind.

.

ya tapered bearing head stock. that's great so does one of mine.
i just get concerned about the rest of the bearings in the machine. there is more than one shaft to worry about. are all the bearings in the head stock and feed box ect roller bearings? what sort of machine is it and why didn't they make it run twice as fast as they did.? i run my machine faster than the factory designed it but not for long and not more than 15 percent.. just interested because im setting one up as well.
aaron
.

Originally Posted by RayG

Hi Ironwood,

Not sure how easy it's going to be to try and figure out what the auto-tuning function has changed.

Just checking...what values are entered for the number of poles F52, and of course.. the ratio of inverter rated current to motor rated current F78.

Also while we are digging around, if you have time while dodging march flies..

F1: acceleration time
F2: deceleration time
F10: rated frequency of motor (factory setting: 50Hz)
F15 upper limit frequency

F11 rated voltage % of motor

F67: Operation Mode
F68: vector voltage compensation
F69: Slip compensation



If all else fails... the next step...

It's a drastic step, but it might be quicker to just reset the drive to factory defaults and re-commission it with the settings you originally entered.


Regards
Ray

Hi Ray, I will try to answer all your questions I can, without going back down to the shed.
F52 - I havent changed this, so assume its still on factory setting of 4 (its a 4 pole motor by the way)
F78 - I have set this to 55, my calculations are 4.7 is 55 percent of 7 (am I on the right track here?)

F1 - I have set to 3
F2 - I have set to 2
F10 - left at 50
F11 - 100
F67 - autotuning has set this to 3 ( I have tried resetting back to 1, but the high current draw continues )
F68 - autotuning has set this to 5
F69 - I havent checked this one, will look tomorrow.

Regarding the resetting the factory defaults, I have decided I will go down that path when I get home from work tomorrow. This problem wasnt evident before I did the autotuning.
I dont know what the current was before I did the autotuning, as I only started to check once the lathe was cutting out on OL.

I have reset F51 back to 10 seconds, I think autotuning set it to 30. Before it cuts out after 10 seconds above 4.7 amps, the current does go up above 6 amps if the pot. is turned up quickly.

Originally Posted by Ironwood

F78 - I have set this to 55, my calculations are 4.7 is 55 percent of 7 (am I on the right track here?)

I would have gone for 70% rounded up from (4.7/7)*100 = 67

Regards
Ray

Originally Posted by RayG

I would have gone for 70% rounded up from (4.7/7)*100 = 67

Regards
Ray

No worries, so that could be causing, or contributing to the problem.

Should have gone looking for that calculator instead of figuring it out in my head

Hi Ironwood,

Well it could possibly be the problem, using 55% you would be effectively setting the rated motor current to 3.85 amps. instead of 4.7 amps

So you will get instantaneous trip at 5.8 amps instead of 7.4 amps, that might do it.

That's assuming I'm reading page 8 of the manual correctly.


The whole purpose of this protection, is just to protect the motor, from overcurrent, i would leave F51 at 30 seconds.

The other thing I meant to ask, and that is, when it trips what is the exact error number?

Regards
Ray