Bridge rectifier earthing

Thread Starter

liefryan

Joined May 4, 2021
13
I have a hydro turbine that generates 3 phase ac, I then rectifier it to run a grid tie inverter, I'm wondering if I should earth the negative output of the rectifier?
 

dendad

Joined Feb 20, 2016
4,251
One way to check would be to measure the resistance between the inverter -ve input and its case. If there is a 0 ohm connection, it is already earthed by the inverter. Otherwise, as @MaxHeadRoom says, no.
 

Thread Starter

liefryan

Joined May 4, 2021
13
I'll go and check between negative and inverter case, I did check between the 3 phase rectifier heatsink and inverter and I was was getting some volts and as the heatsink is exposed I thought it should be earthed but I'm a bit unclear as to what the reciter case is connected to?
 

Thread Starter

liefryan

Joined May 4, 2021
13
So I checked and I have full voltage between the dc negative and the inverter case that is earthed so I cause a short if I earthed the negative?
 

MaxHeadRoom

Joined Jul 18, 2013
26,243
The reading can occur due to leakage, especially using a sensitive high impedance meter for the reading, you would need to provide a resistance to ground and see if the voltage remains or collapses. if the latter, then it usually indicates the reading is just leakage.
 

Thread Starter

liefryan

Joined May 4, 2021
13
The reading can occur due to leakage, especially using a sensitive high impedance meter for the reading, you would need to provide a resistance to ground and see if the voltage remains or collapses. if the latter, then it usually indicates the reading is just leakage.
Good point, what resistance would you suggest? I'm a bit concerned about about damaging the inverter?
 
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