xian
Member
- Location
- Montreal, Qc
For a motor connected with a Wye connection when do you connect the neutral to the common point of the Wye and when do you not.
Cannot find anything in the electric code or by googling.
A collegue told me that if you connect the neutral you allow harmonic current to flow (using a VFD or soft start), and in case of a phase failure it still starts. It seems to me that you put the appropriate protection relay for phase failure detection such as an ANSI 46 or some similar protection relay. As for harmonic current flow, managing this with neutral connection seems wrong and filters should be used.
It also comes to mind a comment someone once said to me that in the case of a minor ground fault on a motor it was much more easy to pickup in a Wye connected motor than a Delta connected motor.
Came across an NFPA discussion paper about a sub-committee for the NEC 1996 edition that was looking into this matter of neutral connection, harmonics, etc. but there was no conclusion. In 2011 there must have been conclusions ?
Can anyone direct me to some standard, or other document to clarify this point please?
Best Regards,
Christian
Cannot find anything in the electric code or by googling.
A collegue told me that if you connect the neutral you allow harmonic current to flow (using a VFD or soft start), and in case of a phase failure it still starts. It seems to me that you put the appropriate protection relay for phase failure detection such as an ANSI 46 or some similar protection relay. As for harmonic current flow, managing this with neutral connection seems wrong and filters should be used.
It also comes to mind a comment someone once said to me that in the case of a minor ground fault on a motor it was much more easy to pickup in a Wye connected motor than a Delta connected motor.
Came across an NFPA discussion paper about a sub-committee for the NEC 1996 edition that was looking into this matter of neutral connection, harmonics, etc. but there was no conclusion. In 2011 there must have been conclusions ?
Can anyone direct me to some standard, or other document to clarify this point please?
Best Regards,
Christian