Burning choke on the AC drive

[panthripu]

Hi everyone
We are facing one problem since long in our workplace.In one of our machine we have a small induction motor which is being control through a sinamics drive. There is choke on incoming of the drive as well as outgoing of the drive.
The outgoing choke is damaging frequently ( the winding getting earthed with the body).
The loading pattern is not continuous duty but it is run once every three to four hours for one hour atleast.
The distance between the drive unit and the motor is almost 250 meters.
Can you please give some idea , what could be the reason ?

Regards

 

[Besoeker]

Hi everyone
We are facing one problem since long in our workplace.In one of our machine we have a small induction motor which is being control through a sinamics drive. There is choke on incoming of the drive as well as outgoing of the drive.
The outgoing choke is damaging frequently ( the winding getting earthed with the body).
The loading pattern is not continuous duty but it is run once every three to four hours for one hour atleast.
The distance between the drive unit and the motor is almost 250 meters.
Can you please give some idea , what could be the reason ?

Regards

Overheating resulting in damage to the winding insulation would seem to be the most obvious explanation. Is the choke designed for inverter duty?

 

[Jraef]

Overheating resulting in damage to the winding insulation would seem to be the most obvious explanation. Is the choke designed for inverter duty?

And is it sized correctly? A common mistake I see made is that people assume that a line reactor and a load reactor are the same, so they use them interchangeably. They are the same from a construction standpoint, but they are SIZED differently. The line side reactor does not have to carry the reactive current of the motor, so it can be smaller. The load side reactor DOES have to carry all of the motor current, active and reactive. If you selected a load reactor and put it on the line side, no problem. But if you selected a line reactor and put it on the load side, it is too small and will burn up. Sound familiar?

And please, I know I’m being “loose” in my description of the line side and reactive current, but let’s not descend into the weeds of the minutiae on this, call it a “metaphor”.

 

[Besoeker]

And is it sized correctly? A common mistake I see made is that people assume that a line reactor and a load reactor are the same, so they use them interchangeably. They are the same from a construction standpoint, but they are SIZED differently. The line side reactor does not have to carry the reactive current of the motor, so it can be smaller. The load side reactor DOES have to carry all of the motor current, active and reactive. If you selected a load reactor and put it on the line side, no problem. But if you selected a line reactor and put it on the load side, it is too small and will burn up. Sound familiar?

And please, I know I’m being “loose” in my description of the line side and reactive current, but let’s not descend into the weeds of the minutiae on this, call it a “metaphor”.

Then there is the dv/dt issue on the load side.

 

[junkhound]

If a common mode choke, suspect triplett harmonics saturating the common mode core, high core losses and overheating.

 

[ptonsparky]

And is it sized correctly? A common mistake I see made is that people assume that a line reactor and a load reactor are the same, so they use them interchangeably. They are the same from a construction standpoint, but they are SIZED differently. The line side reactor does not have to carry the reactive current of the motor, so it can be smaller. The load side reactor DOES have to carry all of the motor current, active and reactive. If you selected a load reactor and put it on the line side, no problem. But if you selected a line reactor and put it on the load side, it is too small and will burn up. Sound familiar?

And please, I know I’m being “loose” in my description of the line side and reactive current, but let’s not descend into the weeds of the minutiae on this, call it a “metaphor”.

:jawdrop::slaphead::ashamed:

 

[panthripu]

Burning choke on the AC drive

Just to add more, there are two small motors( .7kW each) are connected in parallel. And the choke is rated 380-480V+/- 10%,9.4A,0-150Hz, switching frequency 4kHz. The only issue i see is the cable length. The document shows the recommended cable length 100m with shielded cable or 150m with unshielded cable. I tried to find suitable choke useful for 200 to 250m length but could not find/decide the model. The one we use is 6SL3202-0AE21-0CA0.
Any recommendation or suggestion to avoid such failure ?

 

[ptonsparky]

Just to add more, there are two small motors( .7kW each) are connected in parallel. And the choke is rated 380-480V+/- 10%,9.4A,0-150Hz, switching frequency 4kHz. The only issue i see is the cable length. The document shows the recommended cable length 100m with shielded cable or 150m with unshielded cable. I tried to find suitable choke useful for 200 to 250m length but could not find/decide the model. The one we use is 6SL3202-0AE21-0CA0.
Any recommendation or suggestion to avoid such failure ?

Why is the choke, LR, so far away from the drive? As you can tell I'm Not an engineer by any means, but I would think the LR would suffer the same damage a motor does at that distance. Ref Bes post above.

 

[GoldDigger]

Why is the choke, LR, so far away from the drive? As you can tell I'm Not an engineer by any means, but I would think the LR would suffer the same damage a motor does at that distance. Ref Bes post above.

I do not see any statement from the OP as to where along the drive to motor path the LR (Load Reactor) is located. I would expect it to be adjacent to the drive, not the motors. In which case there should be no upstream standing waves to worry about.
OP: Does it get hot then fail (I²R), or is it failing with an insulation failure to ground without first overheating (dV/dt)?

 

[ptonsparky]

For some reason I thought the LR was at the far end, rereading, I see it does not say that.

 

[Jraef]

Just to add more, there are two small motors( .7kW each) are connected in parallel. And the choke is rated 380-480V+/- 10%,9.4A,0-150Hz, switching frequency 4kHz. The only issue i see is the cable length. The document shows the recommended cable length 100m with shielded cable or 150m with unshielded cable. I tried to find suitable choke useful for 200 to 250m length but could not find/decide the model. The one we use is 6SL3202-0AE21-0CA0.
Any recommendation or suggestion to avoid such failure ?

Well it’s nice to know the rating of the choke, but that info is useless without knowing the sizes of the motors.

Also in case you were not aware, when you have multiple motors, you add the cable lengths together to get the total cable length. So if your motors are each 200m from the drive, that’s an 400m cable length. This is a situation in which I would use a dV/dt filter on the output, not just a simpler cheaper reactor. You need to control your capactive charging current at those lengths.

 

[GoldDigger]

Well it’s nice to know the rating of the choke, but that info is useless without knowing the sizes of the motors.

Also in case you were not aware, when you have multiple motors, you add the cable lengths together to get the total cable length. So if your motors are each 200m from the drive, that’s an 400m cable length. This is a situation in which I would use a dV/dt filter on the output, not just a simpler cheaper reactor. You need to control your capactive charging current at those lengths.

Add the lengths unless the major length is a single home run (technically not a feeder unless there is OCPD for each motor) that splits at the end to the two motors.

Sent from my XT1585 using Tapatalk

 

[panthripu]

burning choke on the ac drive

burning choke on the ac drive

The power cable from drive to field is single run cable. The paralleling of the motor is done a near the motors.