I need to test for 100M of insulation resistance at 500V.
Rigged up 4 transformers to make 4x120V
I used a 10M build out resistance, so 100M load should drop voltage roughly 10%....... BUT :'( my cheap rat shack VOM has a roughly 10M input impedance so my rig drops to around 220V before I expose the device I want to test...
Now my source impedance is 5M (10M in parallel with meter 10M), so drop from 100M load is even smaller.
I can measure a difference but not very accurate, and driving voltage should be 500V.
If I get brave I guess is could use my VOM in series and measure current. The VOM has a uA scale.
JR
Rigged up 4 transformers to make 4x120V
I used a 10M build out resistance, so 100M load should drop voltage roughly 10%....... BUT :'( my cheap rat shack VOM has a roughly 10M input impedance so my rig drops to around 220V before I expose the device I want to test...
Now my source impedance is 5M (10M in parallel with meter 10M), so drop from 100M load is even smaller.
I can measure a difference but not very accurate, and driving voltage should be 500V.
If I get brave I guess is could use my VOM in series and measure current. The VOM has a uA scale.
JR