Hi all, I have a problem with a VSD at work thats been confusing. I am a field service engineer for an oil service company, my line of work is in electric submersible pumps (ESP). The ESP motor is a 3 phase induction motor. Power here is 380V 50 HZ.We were using a VSD for motor control. The control scheme used by this VSD is constant V/HZ. When performing a no load test the 2nd phase outputted a lower voltage than the other two. For example when operating the VSD in no load at 50 HZ output frequency, measuring the output terminal phase to phase yields these readings: U-V 270VAC V-W 270VAC U-W 380VAC Obviously the V phase has a problem so I disconnect power and start doing some static checks on the VSD. I check the converter's SCR's and the inverter's IGBT's they all check out according to the VSD manual. Measured the DC bus and it does have the correct DC voltage value. The confusing part is when I connected a small motor to the VSD and started testing it it checked out fine, readings are all balanced and the motor runs smoothly. U-V 370VAC V-W 380VAC U-W 379VAC Tried a no load test after and same thing happened, the V phase is giving erratic readings. And one last observation; the V phase has DC volts in it, when measuring with my AVO meter for DC volts at the output I get those readings: U-V 80 VDC V-W 80 VDC U-W OL I'm sorry if it took too long to explain, I just cant seem to find the problem. According to my static test results all components are intact. Any thoughts?