openinverter forum

Is it common to have the VCU supply voltage of 12V DC to appears on the HV supply terminals,or it is fault caused by wrong connection ?
By turning on the VCU ,measured the same Voltage on the HV supply terminals, with no battery supply on the HV attached .

Please provide more information and pictures. This can be about anything.

I could be wrong but I would say that does not sound right or safe! I doubt there are 400v + diodes in the VCU. I would double check the wiring and the VCU itsself. Are you sure it's from the VCU I would disconnect the hv lines and check continuity as a first step.

Also as tom said you need to give more info. Some photos can help a lot. Also the senario when the 12v appears; Is it all the time, when VCU is in run mode, as soon as you turn it on etc.

Just some general remarks to sort the topic a little bit:
- The VCU itself does not have HV terminals at all. So it cannot (physically) drive any voltage to the HV. There is "something" in between. You need to explain your setup.
- The HV shall be completely isolated. No matter how you measure (voltage, resistance) between chassis and HV, there shall be NO connection, NO voltage, INFINITE resistance. If not, then your setup is defect and highly dangerous. The only exception is, if you have an isolation monitoring device, which will switch some "probe" between the LV and the HV at certain times. If you have such a device, you should refer to the specification of this device, to find out whether it would switch voltage to the HV lines.

Thank You Tom91, Baracuda816 ,Uhi22 for the fast answer & suggestions.The problem is solved ,blank wire mishap,double wire connection.Now everything is fine and the reminals shows no more falt datas.