Motor Overheated Using Motortronics Csd Series Vfd

[Rolando75]

Hello everybody, I hope somebody can help me out on this, I am not very familiar with the drives but I would like to be.

I am experiencing the floowing problem:

I use a 1.5 hp ac motor controlled by a Motortronics CSD Series AC VFD, but it is getting really hot, I tried the motor without the drive and it consumes the name plate amps (even with the same load), but conected through the drive the amps go up to 3 times de name plate FLA.

I tried another drive, same model and got the same results: motor overheat.

Any idea on what I can check will be greatly appreciated.

Thanks in advance.

Rolando.

 

[jraef]

I have a lot of experience with that drive. Please post the model number of the CSD, the info on your power supply and the motor nameplate data. Then also let me know what you have the motor data information set at in the CSD, specifically functions 5, 30, 36, 69, 70 and 72. If Fn 5 = 18, then also report Fn 37 - 41 as well (if Fn 5 is anything other than 18, these do not matter.

[Rolando75]

I have a lot of experience with that drive. Please post the model number of the CSD, the info on your power supply and the motor nameplate data. Then also let me know what you have the motor data information set at in the CSD, specifically functions 5, 30, 36, 69, 70 and 72. If Fn 5 = 18, then also report Fn 37 - 41 as well (if Fn 5 is anything other than 18, these do not matter.

 

Thanks for you answer and interest to help, the info is bellow:

CSD Model: CSD-202-N

 

Motor info:

Cat. No. 120024.00

Model: C143T17FC2E

Rpm: 1740

HP: 1

FR: E143TC

Max. amb.: 40C

INS. cl.: B4

NEMA NOM EFF: 78

ph: 3

hz: 60

V: 208-230

FLA: 3.4 amps

 

Our power supply info

Voltage between phases A-B : 206 Vac

Voltage between phases A-C : 203 Vac

Voltage between phases B-C : 205 Vac

 

Function values:

Fn5:0012

Fn30:240.0

Fn36:0004

Fn69:0000

Fn70:006.1

 

 

 

 

 

 

 

I have a lot of experience with that drive. Please post the model number of the CSD, the info on your power supply and the motor nameplate data. Then also let me know what you have the motor data information set at in the CSD, specifically functions 5, 30, 36, 69, 70 and 72. If Fn 5 = 18, then also report Fn 37 - 41 as well (if Fn 5 is anything other than 18, these do not matter.

 

I did not mentioned that Fn18=12 so I did not includ Fn37 to 41.

[jraef]

Thanks for you answer and interest to help, the info is bellow:

CSD Model: CSD-202-N

 

Motor info:

Cat. No. 120024.00

Model: C143T17FC2E

Rpm: 1740

HP: 1

FR: E143TC

Max. amb.: 40C

INS. cl.: B4

NEMA NOM EFF: 78

ph: 3

hz: 60

V: 208-230

FLA: 3.4 amps

 

Our power supply info

Voltage between phases A-B : 206 Vac

Voltage between phases A-C : 203 Vac

Voltage between phases B-C : 205 Vac

 

Function values:

Fn5:0012

Fn30:240.0

Fn36:0004

Fn69:0000

Fn70:006.1

I did not mentioned that Fn18=12 so I did not include Fn37 to 41.

 

OK.

First off, record any changes you made (if any) to the standard factory programming such as ramp times, I/O programming etc. and then set Fn 123 to a value of "1111". This will reset everything back to the factory defaults, clearing any erroneous setting that may have been in there. then go back in a do the following:

 

Change Fn 30 to 208V. You were over saturating the motor because the VFD was unable to deliver the proper voltage (240) given the low supply (208 nominal). You always need to match the programmed voltage to both the supply and the motor if the supply is lower than the motor nameplate voltage. Your nameplate means that the motor was designed to work on 208V, but you were telling the VFD to attempt to drive it at 240V. yet you didn't have 240V available and the VFD cannot create voltage, so it was using a V/Hz pattern of a 240V source, but was unable to actually deliver it. The motor had severely less torque that it was rated for, which would allow it to run in high slip all the time, which would make it draw more current. Combine that with the following...

 

Change Fn 70 to 003.4, that is the OL protection for your motor. The VFD was allowing your motor to overload; it wasn't going to pick up an overload until it saw 6.1A!

[Rolando75]

OK.

First off, record any changes you made (if any) to the standard factory programming such as ramp times, I/O programming etc. and then set Fn 123 to a value of "1111". This will reset everything back to the factory defaults, clearing any erroneous setting that may have been in there. then go back in a do the following:

 

Change Fn 30 to 208V. You were over saturating the motor because the VFD was unable to deliver the proper voltage (240) given the low supply (208 nominal). You always need to match the programmed voltage to both the supply and the motor if the supply is lower than the motor nameplate voltage. Your nameplate means that the motor was designed to work on 208V, but you were telling the VFD to attempt to drive it at 240V. yet you didn't have 240V available and the VFD cannot create voltage, so it was using a V/Hz pattern of a 240V source, but was unable to actually deliver it. The motor had severely less torque that it was rated for, which would allow it to run in high slip all the time, which would make it draw more current. Combine that with the following...

 

Change Fn 70 to 003.4, that is the OL protection for your motor. The VFD was allowing your motor to overload; it wasn't going to pick up an overload until it saw 6.1A!

Thanks a lot. I will give this a try and will get back here to report results.

Thanks again!

Rolando.

 

[Rolando75]

Hi, here´s what I got:

I got the a record of the changes made to the factory settings, so I proceeded to reset everything to the way it was at the factory.

I set Fn30 to 208, Fn70 to 3.4, Fn10 to 1 and tried it, but I could read in each line high ampereage, from 14 amps to 16 amps, too high, with these few tests the motor did not overheat but if I let it run it sure will.

Any thoughts about this?

Thanks.

Rolando.

[jraef]

Are you reading the amperage through the VFD display, or are you trying to read it through a clamp-on ammeter?

[Rolando75]

Are you reading the amperage through the VFD display, or are you trying to read it through a clamp-on ammeter?

Clamp-on ammeter.

 

[marke]

The current readings given by clamp on ammeters can give very high errors depending on the ammeter and how it operates.

The current on the input of the drive is very different from the current to the motor as the voltage applied to the motor reduces with speed and VA in = VA out. At half speed, the output voltage will be half, and the output current will be twice the input current.

 

The input current is discontinous, it consists of pulses of current coinciding with the peaks of the voltage waveform. If there is a large DC Bus choke fitted, the current pulses could be as wide as 120 degrees per half cycle. If there is no DC bus choke fitted, then the current pulses could be as narrow as 20 degrees per half cycle. As the current pulses get narrower, the amplitude gets higher. If you use an ammeter that is responsive to the amplitude of the pulses and assumes a sinewave current, you will get a very high current reading which is more a representation of the peak current than the average or RMS current.

 

Current measurements should be made on the output only, with a true RMS meter with a wide bandwidth, prefferably down to DC.

You are best to rely on the current reading on the drive itself.

 

Best regards,

[Rolando75]

The current readings given by clamp on ammeters can give very high errors depending on the ammeter and how it operates.

The current on the input of the drive is very different from the current to the motor as the voltage applied to the motor reduces with speed and VA in = VA out. At half speed, the output voltage will be half, and the output current will be twice the input current.

 

The input current is discontinous, it consists of pulses of current coinciding with the peaks of the voltage waveform. If there is a large DC Bus choke fitted, the current pulses could be as wide as 120 degrees per half cycle. If there is no DC bus choke fitted, then the current pulses could be as narrow as 20 degrees per half cycle. As the current pulses get narrower, the amplitude gets higher. If you use an ammeter that is responsive to the amplitude of the pulses and assumes a sinewave current, you will get a very high current reading which is more a representation of the peak current than the average or RMS current.

 

Current measurements should be made on the output only, with a true RMS meter with a wide bandwidth, prefferably down to DC.

You are best to rely on the current reading on the drive itself.

 

Best regards,

 

Thanks for your comments and this valuable information I didnt know.

But I still do not quite understand why if I have 2 machines very alike, in the same motor I have a big difference in the amps and the one with the problem gets very hot, really hot, I am afraid of burning the motor if I let it run like that, because it gets really hot.

Any other idea of why it can get overheated?

Thanks in advance.

Rolando.

 

[jraef]

Thanks for your comments and this valuable information I didnt know.

But I still do not quite understand why if I have 2 machines very alike, in the same motor I have a big difference in the amps and the one with the problem gets very hot, really hot, I am afraid of burning the motor if I let it run like that, because it gets really hot.

Any other idea of why it can get overheated?

Thanks in advance.

Rolando.

 

Is it still getting really hot after you adjusted the V/Hz ratio as I had told you earlier, or are you still going by the previous experience. The fact that your old settings were over saturating that motor would explain the additional heat at that time. If it is still just as hot, it may be something else.

 

Try looking at your Carrier Frequency setting. Some motors cannot handle higher settings that people use in order to quite down the "whine" sound that a motor makes running from a VFD. Check Fn 43, which sets the carrier frequency (CF). A higher CF makes less audible noise, but increases the switching losses in the VFD and the motor, which makes the motor run hotter. A lower CF is better for the motor, but it will make a louder whining sound when running. Older versions of the CSD defaulted to 2kHz, but they changed it because users perceived them as being inferior to other VFDs that used higher CFs. If yours is a relatively newer CSD, the factory default is now 10kHz (Fn 43 set to a value of 14), which is sometimes too high for certain motors. Lower it to 1.2kHz (set Fn 43 to a value of 1) and see if you can put up with the noise; that should make it run cooler.