GusD
Electrical
- Mar 14, 2003
- 231
Voltage measurements on a VFDrive with IGBTs in the inverter.
We have just installed a new VFD (IGBT) to replace an older VFD (GTOs)that gave us a lot of problems over the years.After commissioning the unit we experienced some problems with blown power fuses as well as converter power Diodes .
When we measure the output voltage to motor we see 660 volts instead of 575/600 voltsAC.These tets meters are all digital and quite reliable.The 3Ph/575V input voltage to the system increases to 615v at the output of a RC Harmonic filter and to the input of the converters.
I don't believe that we applying 660 volts RMS to the this motor.My question is why don't these meters read a True RMS even if this voltage is a pulse generated voltage?
I also have measured spikes when on PK/Hold mode of approx 1450 volts.This is a fairly normal spike for an Inverter operation.I would like to know how close to RMS value is this spike?
Thank you for the help
GusD
. GusD
We have just installed a new VFD (IGBT) to replace an older VFD (GTOs)that gave us a lot of problems over the years.After commissioning the unit we experienced some problems with blown power fuses as well as converter power Diodes .
When we measure the output voltage to motor we see 660 volts instead of 575/600 voltsAC.These tets meters are all digital and quite reliable.The 3Ph/575V input voltage to the system increases to 615v at the output of a RC Harmonic filter and to the input of the converters.
I don't believe that we applying 660 volts RMS to the this motor.My question is why don't these meters read a True RMS even if this voltage is a pulse generated voltage?
I also have measured spikes when on PK/Hold mode of approx 1450 volts.This is a fairly normal spike for an Inverter operation.I would like to know how close to RMS value is this spike?
Thank you for the help
GusD
. GusD
