Neutral grounding resistor question

[ArchieMedes]

I would like to ask what is the meaning of the 150mA in the NER (neutral ground/earth resistor) as attached in the drawing. This NER is connected to the secondary side of the transformer's neutral/star point. Thanks in advance.

 

[templdl]

What you have provided is just a small part of the entire spec. What I would be looking for is something more in the written part of the spec.
In my opinion it certainly appears to be ungrounded and that the NER is part of a ground detection system and not a grounding resistor as one would think. What I don’t see is that it is supposed to do should it detect ground current. What I would be looking for is an alarm of a breaker being tripped.
If I were to compare it to something it would be an ungrounded delta where a ground detector is used to illustrate some sort of concept. If one line goes to ground you want to know about it before a second line goes to ground.
In your case there's a bigger risk when one is isolating the system from ground because of human safely and electric shock because of the 150MA sensitivity.
Again, with out having access to the entire spec this is only an assumption.
Oh, and the 50hz, is this domestic or foreign?

 

[ArchieMedes]

What you have provided is just a small part of the entire spec. What I would be looking for is something more in the written part of the spec.
In my opinion it certainly appears to be ungrounded and that the NER is part of a ground detection system and not a grounding resistor as one would think. What I don?t see is that it is supposed to do should it detect ground current. What I would be looking for is an alarm of a breaker being tripped.
If I were to compare it to something it would be an ungrounded delta where a ground detector is used to illustrate some sort of concept. If one line goes to ground you want to know about it before a second line goes to ground.
In your case there's a bigger risk when one is isolating the system from ground because of human safely and electric shock because of the 150MA sensitivity.
Again, with out having access to the entire spec this is only an assumption.
Oh, and the 50hz, is this domestic or foreign?

Yes this told me that this is an ungrounded system but when I saw there is a resistor (NER) to the ground from the transformer star point, it looks like the system now is not totally isolated or ungrounded system. Not only from this drawing but downstream this transformer with NER, there are some delta load which has an insulation monitoring device. This insulation monitoring device (connected to to the phase to phase of the transformer output and ground) registers a low insulation to ground and is tripping on earth leakage/fault. This is the reason why I want to know about this NER. If the NER was removed, will the insulation monitoring device register a high resistance to ground? I believe the NER is the one causing the tripping/low IR to ground.