3P VFD 1.5 KW motor conveyor

[Savdar1810]

Question for someone... I have a 3P 1.5kw motor gearbox on a 5meter conveyor driven by a 3.7kw omron VFD, Frequency is set at 70/80hz (required for needed speed on this existing drive train) and voltage going out to motor is something crazy like 470v between line and earth, Its way to high I'm thinking for a motor that small, think I'll need to upgrade to a 2.2kw or 3? Voltage output monitoring screen says 403 volts but that will be for all 3 phases which is still reading false no? So I don't know if there's maybe a fault in the vfd itself? There's no load on conveyor when running theses voltages and no friction between gearbox, conveyor belts and pulleys so can't think of reason why voltage would be so high, even on 50hz its pretty high. It being a 3.7kw vfd I am not sure if it's maybe been ran on a 3.7kw motor or less in the past and they have just thrown any old motor on to replace it when it's faulted. Opinions welcome

 

[Savdar1810]

Question for someone... I have a 3P 1.5kw motor gearbox on a 5meter conveyor driven by a 3.7kw omron VFD, Frequency is set at 70/80hz (required for needed speed on this existing drive train) and voltage going out to motor is something crazy like 470v between line and earth, Its way to high I'm thinking for a motor that small, think I'll need to upgrade to a 2.2kw or 3? Voltage output monitoring screen says 403 volts but that will be for all 3 phases which is still reading false no? So I don't know if there's maybe a fault in the vfd itself? There's no load on conveyor when running theses voltages and no friction between gearbox, conveyor belts and pulleys so can't think of reason why voltage would be so high, even on 50hz its pretty high. It being a 3.7kw vfd I am not sure if it's maybe been ran on a 3.7kw motor or less in the past and they have just thrown any old motor on to replace it when it's faulted. Opinions welcome

View attachment IMG_20190307_040135.jpg

 

[Bobster]

You will not be able to measure the actual voltage given by the output of a VSD with a digital multi meter, especially to earth as there will likely not be a true reference.

Absolutely no harm in using a larger rated VSD to run a smaller motor. (Generally as long as it's load is 10% of what it is rated for, this is due to CT accuracy).

Just ensure that the FLC limit is set correctly for the motor.

Running a motor faster than it is rated if it is in U/F mode, will cap the voltage at around 50hz (If that's what the motor details in the VFD are capped at). Going above this will not keep increasing the voltage, an because of this you will see a reduction in torque.

A faster RPM than what the motor is rated at will shorten the life span of the bearings, and if it's a cheap non invertor rated motor kill the winding insulation.

Parameter N032 is what you need to check for FLC, manual is here:

https://www.myomron.com/downloads/1.Manuals/Inverters/3G3HV/3G3HV Series Catalog I900-E1-3.pdf

 

[Savdar1810]

You will not be able to measure the actual voltage given by the output of a VSD with a digital multi meter, especially to earth as there will likely not be a true reference.

Absolutely no harm in using a larger rated VSD to run a smaller motor. (Generally as long as it's load is 10% of what it is rated for, this is due to CT accuracy).

Just ensure that the FLC limit is set correctly for the motor.

Running a motor faster than it is rated if it is in U/F mode, will cap the voltage at around 50hz (If that's what the motor details in the VFD are capped at). Going above this will not keep increasing the voltage, an because of this you will see a reduction in torque.

A faster RPM than what the motor is rated at will shorten the life span of the bearings, and if it's a cheap non invertor rated motor kill the winding insulation.

Parameter N032 is what you need to check for FLC, manual is here:

https://www.myomron.com/downloads/1.Manuals/Inverters/3G3HV/3G3HV Series Catalog I900-E1-3.pdf

Cheers Rob will have a look

 

[SheffSimon]

Something I have come across and used recently is 87Hz operation, particularly on small motors like the one in question.

Basically running the drive in v/f operation, drive parameters as per nameplate, motor connected in delta rather than star, frequency limit set 87Hz, max power set to 1.7 times nameplate.

This technique sounds applicable to your problem. Google 87hz motor operation, there's stacks of info out there.

SIOS - https://support.industry.siemens.com/cs/document/25338130/sinamics-g%3A-operating-motors-at-higher-frequencies?dti=0&lc=en-WW

 

[LeeH]

Rob has giving all you need but I can add a little.

You meter needs to be true RMS, not just digital.

Motors often are rated above the nameplate rating. Eg a 4 pole is 1500 rpm but will be good for double that as the mechanics will be built and balanced the same as a 2 pole 3000 rpm motor. It simplifies the production line.