Three Phase Rectifier Voltage Fault

Thread Starter

pujulde

Joined Jul 24, 2013
108
Hi, everyone. I came across with a bit strange to me case. System consists of :
1) three phase transformer(secondary 560Vac);
2) Input line reactor;
3) Three phase rectifier;
Measurements of the output of rectifier showing around 1200 Vdc. As I mentioned above the input Voltage is 560Vac. What could it be? Could be some affect of damaged line reactor?
And the AC voltage on DC bus is around 120Vac. Any suggestions?
Thanks
 

panic mode

Joined Oct 10, 2011
1,789
what exactly are you using to take measurements? i have collection of multimeters and they all go up to 1000VDC. none of them is capable of directly measuring 1200VDC.

what is the waveform? if this is feeding some inverter, there will be a lot of artifacts. do you have a TrueRMS instrument?

how balanced you three phase system is?
 

AlbertHall

Joined Jun 4, 2014
8,385
Is the 560VAC secondary voltage measured phase to phase or phase to neutral?
Is this a full-wave rectifier (6 diodes)?
Is there an output smoothing capacitor?
 

Thread Starter

pujulde

Joined Jul 24, 2013
108
what exactly are you using to take measurements? i have collection of multimeters and they all go up to 1000VDC. none of them is capable of directly measuring 1200VDC.

what is the waveform? if this is feeding some inverter, there will be a lot of artifacts. do you have a TrueRMS instrument?

how balanced you three phase system
The reading was taken by scopemeter, there is no any load to the rectifier ,
 

Thread Starter

pujulde

Joined Jul 24, 2013
108
Is the 560VAC secondary voltage measured phase to phase or phase to neutral?
Is this a full-wave rectifier (6 diodes)?
Is there an output smoothing capacitor?
Its phase to phase voltage and full- wave rectifier, across the diodes are used just RC snubber circuit
 
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