Insulation monitoring in some marine isolated electrical systems

[Junior01]

Hi,
In some marine isolated electrical systems I saw that only one phase insulation resistace is monitored. Why? If something happens on other phases I will have no information about that or...?
Regards!

 

[jim hardy]

If it's ungrounded, or more correctly high impedance grounded, a ground anyplace will upset the balance and is easily detected.

I'm more accustomed to seeing the neutral monitored, though a phase would work as well.

Here's a description of one type of ground monitor
http://apps.geindustrial.com/publib...NR=Installation and Instruction|GEI-72116|PDFand a tutorial on basics
http://apps.geindustrial.com/publib...e-Gro?TNR=White Papers|Resistance-Gro|genericFor a thorough lesson search on "IEEE GREEN BOOK" .

You need to give us a sketch of what sort of system it is you have in mind. I have no idea.