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Joined: Jul 2001
Posts: 599
J
JBD Offline
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Originally Posted by Yoopersup
See Page 230.200 Exhibit 230.31. Thats the way it is. the disconnects are remote from the transformers line sideas per 230.204 (B)location per 230.205(A) which refers you to 230.70 (A)
Load side of transformers Disconnect switchs in Building Nearest point of entrance 240.21 (C) 4.


Customer owned transfromers need overcurrent protection per article 450.

Single phase cutouts cannot be used as the service disconnect device. Although they can be used to provide overcurrent protection for the service, feeder conductors, or transformers.

As George keeps saying, above 600V the service disconnect must be a multi-pole device. Also,location is not as important as is the type of equipment.

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Joined: Mar 2003
Posts: 849
Y
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Page 155 2005 N.E.C. Exhibit 230.31 Code handbook Clearly shows secondary protection for the transformer is NOT required till the feeders enter the Building. The Conductors must be protected as I stated before in 240.21.
This is a common pratice done on most college campuses.(notice no big disconnect switchs by the transformers next to the buildings)read 240.4 F . 450.3 refers you to article 240 in FPN"s for overcurrent protection of conductors.I agree the Primary must be protected by a serice rated 3 pole fuseable disconnect but a didconnect is NOT required on the secondary side of a HV to LV transformers located remote and outside of a building.

Joined: Sep 2005
Posts: 120
Z
Zog Offline
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Both load breaks should be fused for protection o feach transformer, and grounded. There are also termination issues here and testing requirements. Either you or the owner should have a certified testing company run acceptance testing on this installation.

There are about 10 NETA companies in Michigan, 5 in detroit alone. You can fond one at www.netaworld.org


MV/HV Testing Specialist, "BKRMAN"
Joined: Mar 2003
Posts: 849
Y
Member
Usually High Voltage stress cones Kits on switchs, High Voltage elbows on Transformers (most so easy now compair to 20 yrs back), High Pot the cables to factory specs. Most of this is done in house with a Qualified Electrical contractor. I find Most Electrical inspectors and electricans have a Very limited info on any thing over 600 volts.
Almost every College has HV switchgear in a seperate Blg. Fused then cpl . feeders< then taps off thoses feeders in manholes , then to transformer in or right outside of each building , then to 480/277 to gear in room. This is all maintained and owner owned, from the line side of the ist set of switch gear thurout the campus. Paper mills are the same .

Joined: Sep 2005
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Zog Offline
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DC Hipots are not acceptable anymore, considered a destructive test by the IEC, IEE, and NETA standards.

A AC VLF, Tan Delta, or PD test would be acceptable.


MV/HV Testing Specialist, "BKRMAN"
Joined: Jul 2001
Posts: 599
J
JBD Offline
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I guess I am confused. I thought your original question was dealing with the transition from the utility to the primary of customer owned transformers, now you are including their secondaries in the discussion.

What questions are you still working on?

Joined: Mar 2003
Posts: 849
Y
Member
The Original Question was about the service disconnect switches ect. But when Feeders were brought up I just added additional info. As far as Hi potting Most factory specs. usually Put a limit on the voltage you can use as far as I've always know.

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