Hey guys,
I just want to clarify something about the purpose of a neutral-to-ground resistor based on the different ways it can be connected.
PPI Exam 1 question 14 has a resistor connected between the neutral point of the 3-phase source and ground. The purpose of this resistor is to allow sufficient ground current for detection of a capacitive ground fault in this otherwise ungrounded system.
NCEES practice exam question 134 also has a resistor connected between neutral and ground, but here the purpose of this resistor is to limit the ground current and prevent damage only.
The PPI exam solution does state that the neutral-to-ground resistor's purpose can differ depending on how it is connected. So my question is:
How can I tell what the neutral-to-ground resistor's purpose is, based on how it is connected? Are there any discerning or distinguishing characteristics I should look out for in determining what a neutral-to-ground resistor is used for?
There are a few differences that I see between both problems.
Neutral-to-Ground resistor used to allow sufficient ground current for detection of fault - PPI question 14
I just want to clarify something about the purpose of a neutral-to-ground resistor based on the different ways it can be connected.
PPI Exam 1 question 14 has a resistor connected between the neutral point of the 3-phase source and ground. The purpose of this resistor is to allow sufficient ground current for detection of a capacitive ground fault in this otherwise ungrounded system.
NCEES practice exam question 134 also has a resistor connected between neutral and ground, but here the purpose of this resistor is to limit the ground current and prevent damage only.
The PPI exam solution does state that the neutral-to-ground resistor's purpose can differ depending on how it is connected. So my question is:
How can I tell what the neutral-to-ground resistor's purpose is, based on how it is connected? Are there any discerning or distinguishing characteristics I should look out for in determining what a neutral-to-ground resistor is used for?
There are a few differences that I see between both problems.
Neutral-to-Ground resistor used to allow sufficient ground current for detection of fault - PPI question 14
- Used in an otherwise ungrounded system that only has capacitance to ground
- Used in a grounded (grounded Y) system
- Has a ground-fault relay wired to the 3-pole circuit breaker
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