Temperature Rise Test on Panels with VFD Feeders

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Sure there is! Connect the load and run it!

Or did you mean to run with a load that actually is not a load?

Then see here!

Love the loop back...

Hook up a load bank.

Your worst case for producing heat in the cabinet will be with the VFD set for maximum operating frequency at maximum rated load at maximum allowable carrier frequency where your losses in the entire circuit are greatest, so yes, you MUST conduct a load test. If you cannot do that with a dynamometer, you must simulate it with a load bank.

I once mistakenly programmed a closed loop VFD for a 1024 ppr Encoder but it was really a 1200 ppr Encoder on the motor. The motor was free and when they cracked the throttle it went to 150% amps turning slowly. What does the lumberjack [JRaef] think of fooling with the parameters to load the VFD.

^{I once mistakenly programmed a closed loop VFD for a 1024 ppr Encoder but it was really a 1200 ppr Encoder on the motor. The motor was free and when they cracked the throttle it went to 150% amps turning slowly. What does the lumberjack [JRaef] think of fooling with the parameters to load the VFD.}

Hmmm... interesting idea, never thought of that. Over fluxing the motor as a way to increase the current out of the drive without actually requiring the motor to have a load connected to it, by essentially turning the motor into a heater. We do a similar thing for STOPPING a motor, called Flux Braking. I think it could be adapted. You couldn't do it for long though, the motor wouldn't take it.

Oh, unless you use a motor much larger than the VFD capacity, and TELL the drive it is smaller so it's easier to over flux it!

Probably not a good idea in this case when trying to calculate temperature rises as these tests can take a while.

You can put full load on VFD and test the same by temperature

Using what?

We have never bothered because the heat loss figures were clearly indicated in the VFD manuals and the heat loss of other simple resistive and inductive devices could be calculated or estimated using ohms law (etc).

If you really wanted to perform the test you could connect a resistive or motor load to the VFD. You may be able to hire one if making one is going to be too expensive.

Perhaps you should check the manual or VFD application notes again.

^{We have never bothered because the heat loss figures were clearly indicated in the VFD manuals and the heat loss of other simple resistive and inductive devices could be calculated or estimated using ohms law (etc).}

If you were needing to get a UL listing on an enclosed version of a VFD that is not already offered in a listed enclosed version, or for example to put it in an MCC cabinet and get a UL845 listing, UL would not accept calculated values, you must do a physical test. I would use the calculated values to know what to use IN that physical test so as to only do it once, but the actual test must be performed.

Thanks for your really interesting inputs. I just wanted to know further, that what if I keep dummy equipments of same volume as that of the VFDs chokes filters MCCB fuse etc inside an MCC panel and keep some equivalent heater loads (Watt loss that specified in manufacturers catalog) inside these dummy equipment and then check for surrounding ambient which I want to be around 50 deg celcius or less. Will it give me the same results and if not what is the real difference between passing actual current or creating a heat loss through small heater.

Also what can be an ideal way of heat dissipation. Whether an inbuilt VFD fan suffices or external fans are needed. Above 22kW VFD feeders generally produce lot of heat. At present I am thinking of providing air inlet through indivdual feeder compartment and taking it out through the cable chamber at the side by giving a fan on top. Any ideas on ventilation shall be highly appreciated.