I have VFD Siemens Sinamics Power Module 240 which is running a 30KW 54.5Amps 3 phase induction motor. It has 2 braking choppers connect of 1250W 27Ohms each. One of the chopper is burnt.
What happens if I replace one of the chopper with a slight higher rated one for example 1500KW 40 Ohms? Or if I replace both of them with a chopper of 3KW 70 Ohms?
Will either of the options have a negative effect on the Drive? Which would be the better option?
Fund attached pictures of the VFD & Motor details as well as the existing braking chopper that is faulty.

Thanks

 

If those are resistors intended to absorb excess buss energy during braking then changing from 27 ohms to 40 ohms will allow a higher voltage to develop and that may cause a problem.
Do you know what caused the problem that caused the one to burn ? And did the burned unit fail or just burn a bit? Mostly, parts do not fail for no reason, and so that reason needs to be addressed before replacing the failed part. Otherwise the replacement part may also be damaged.
For others to be able to provide correct advice we do need complete information, otherwise the answers are only guesses, and some guesses may not apply to the system you have.

 

Hope this helps you

 

The only thing is your inverter power rating is much higher . Which lends to regenerative braking chopper. Capabilities

 

I looked at the manual and I see no mention of a braking chopper. I do see braking resistors described, and it seems that if one has failed then the replacement should be selected to provide a similar resistance but with a greater power dissipation ability.
Why is a resistor being called a chopper???

 

The braking chopper is part of the VFD G120 I gather, I would suspect the higher wattage chopper resistor would work, but you may not get the result you need in braking?
Max.

 

Why is a resistor being called a chopper???

I humbly ask for your forgiveness for creating confusion in this thread. The break resistor is an integral part of a control system where the chopper controls the DC link voltage by connecting the brake resistor across the link when the voltage reaches a predetermined level, dissipating the excessive energy. My mistake .

 

The braking chopper is part of the VFD G120 I gather, I would suspect the higher wattage chopper resistor would work, but you may not get the result you need in braking?
Max.

I read the manual and did not see any reference to "chopper", and certainly no reference to a braking chopper. So I still ask why is a totally misleading word used? The resistor used to dissipate the excess braking power is just that, there is no "chopper" involved. So it will be useful to get an explanation of why the TS used that word.

 

The typical method of braking on a VFD is by a solid state switching of the resistor, the degree of braking is based on the actual rpm of the motor.
Chopping or PWM is used for the switching device.
Max.

 

So I still ask why is a totally misleading word used?

Page 38 of the manual under Common performance ratings of the Power Module. Do you see where it says breaking method. & It seems to me I have made you very frustrated .I apologise for that. Your question does hold merret ,but I fear if I continue this course the mediator will discontinue my account here because I just recently joined up .and I really enjoy reading all the responses to different posts. Good stuff!!



https://www.eeeguide.com/wp-content/uploads/2018/02/Chopper-Controlled-Resistance.jpg

 

It seems to me I have made you very frustrated .I apologise for that. Your question does hold merret ,but I fear if I continue this course the mediator will discontinue my account here

Nothing you have posted so far would require disciplinary action, IMHO!
Max.

 

Page 38 of the manual under Common performance ratings of the Power Module. Do you see where it says breaking method. & It seems to me I have made you very frustrated .I apologise for that. Your question does hold merret ,but I fear if I continue this course the mediator will discontinue my account here because I just recently joined up .and I really enjoy reading all the responses to different posts. Good stuff!!



https://www.eeeguide.com/wp-content/uploads/2018/02/Chopper-Controlled-Resistance.jpg

Posts and accounts are not terminated for other than being very dangerous or quite nasty. Some threads wander very far astray from where they started, and keep on going. and any post proposing some form of "perpetual motion" is subject to closing, although I think that they are funny, and I never take them seriously.

 

Boy am I happy to hear that because I was going to squish you like mr. Bill