I have dozens of VFDs used to run submersible pumps in an oil field. A particular line of VFDs has been struggling with VFD Overtemperature issues in the summer heat. I have noticed that if I get the drive output voltage above 450 V, the VFD heat sinks are cooler and avoid the temperature shutdown. It also appears the closer the output voltage is to the input voltage (480V), the cooler the VFDs run. Can anyone help explain why this is?

 

cl302i
1. What are depths?
2. What are drop-cable parameters, 3 conductor 3-foil, or 4 conductor Flat?
3. Are source voltage phases and currents balanced?
4. Have you tried to elevate source voltage to say 490V?
Regards, Phil Corso

 

@PhilCorso Depths are around 8500 feet. Cable is 3-conductor flat profile lead-sheathed 2 gauge. The source voltages/currents are balanced. I have not tried to elevate the source voltage yet.

And just for everyone's info - these are SPOC drives and I've seen this happen on most of their units, particularly when output voltage is below 440 volts on a hot day.

 

@cl302i
5. Are you sure that Line-currents and Ph-Ph voltages are equal?
6. Are you able to read Ph-Ph Voltage and Line-Current Harmonics?
7. What is Vibration-Level?
8. Is this same oil-field we talked about in 2020?
9. Have you measured temperature of SPOC equipment?
Phil

 

@PhilCorso
Yes.
I can read P-P voltage but not the Line-Current harmonics. A power quality study is going to be done, but this phenomena exists everywhere around the country for these drives.
Vibration is minimal (mostly new equipment with minimal wear). Also, the downhole vibration is independent of the issue I am talking about.
It's not the same field. I have this issue in multiple fields that use these SPOC drives.
I have measured the temperatures on the drives. They run between 60 degrees C up to 85 degrees C. If I increase the frequency of the drive, and therefore increase the output voltage of the drive, the temperature of the drive decreases.

 

I have Siemens VFD G-120, there was a problem when input Breaker on, then VFD, not ON, and VFD Start after 6 to 8 hours automatically

 

cl302i
Increased frequency means increased speed means greater cooling effect!
Phil Corso

 

cl302i
Increased frequency means increased speed means greater cooling effect!
Phil Corso

Alrighty guys, I got to the bottom of the situation.
At lower frequencies, the drive's pulse widths occur more often but are smaller. At higher frequencies, the pulse widths are wider and occur less often. The fact that the pulse widths occur more often at lower frequencies causes the IGBTs to produce more heat. These particular drives just have insufficient cooling to handle that heat when the drive output voltage is below 450V.

 

Alrighty guys, I got to the bottom of the situation.
At lower frequencies, the drive's pulse widths occur more often but are smaller. At higher frequencies, the pulse widths are wider and occur less often. The fact that the pulse widths occur more often at lower frequencies causes the IGBTs to produce more heat. These particular drives just have insufficient cooling to handle that heat when the drive output voltage is below 450V.