Primary tap connections
- Thread starter jam
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- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Re: Primary tap connections
You would need to have a loop feed or another source at the other end of the cable. A loop feed in my mind is a cable that loops in and out at each transformer and back to the source. You can isloate a bad cable with the LB Elbows and not have the other transformer out for a long period of time. How many transformers do you have? How big an area is this? Industrial customer?
[ June 26, 2003, 11:47 PM: Message edited by: bob ]
You would need to have a loop feed or another source at the other end of the cable. A loop feed in my mind is a cable that loops in and out at each transformer and back to the source. You can isloate a bad cable with the LB Elbows and not have the other transformer out for a long period of time. How many transformers do you have? How big an area is this? Industrial customer?
[ June 26, 2003, 11:47 PM: Message edited by: bob ]
- Location
- Illinois
- Occupation
- retired electrician
Re: Primary tap connections
Bennie,
You can "tee" tap medium voltage cable. There are termination kits that will provide the required stress reduction. Its been a long time since I've done one, but we used stress cones on each of the 3 cables and then made the connection to the "tee". The "tee" was insulated and covered with a flexible wire mesh to provide the shielding. This mesh was tied to the shields of the three cables. Here are the instructions for a 3M TEE Tape Splice Kit for 15kV shielded cable.
Don
[ June 28, 2003, 02:47 PM: Message edited by: don_resqcapt19 ]
Bennie,
You can "tee" tap medium voltage cable. There are termination kits that will provide the required stress reduction. Its been a long time since I've done one, but we used stress cones on each of the 3 cables and then made the connection to the "tee". The "tee" was insulated and covered with a flexible wire mesh to provide the shielding. This mesh was tied to the shields of the three cables. Here are the instructions for a 3M TEE Tape Splice Kit for 15kV shielded cable.
Don
[ June 28, 2003, 02:47 PM: Message edited by: don_resqcapt19 ]
charlie
Senior Member
- Location
- Indianapolis
Re: Primary tap connections
You do not want to design you system that way! Use loop feed (6 bushing, 2 bushing for single phase) pad mounted transformers. If you have a cable fault from the tap to the transformer, you would be out of business. By using loop feed, it doesn't matter where a fault happened, the bad cable could be switched out and the whole system could be up and running again.
A loop feed transformer works by looping the primary, unfused, through from bushing to bushing. A bay-o-net fuse goes from the jumper to the primary coil and may be removed and replaced with a shotgun hot stick.
With a loop system, you need an open point and to feed the loop from both ends. You need lightning arresters on both ends of the open point. The MV cable needs to be large enough to handle the total load of the loop. You need two qualified people to do any work on the system whenever any switching is done.
You do not want to design you system that way! Use loop feed (6 bushing, 2 bushing for single phase) pad mounted transformers. If you have a cable fault from the tap to the transformer, you would be out of business. By using loop feed, it doesn't matter where a fault happened, the bad cable could be switched out and the whole system could be up and running again.
A loop feed transformer works by looping the primary, unfused, through from bushing to bushing. A bay-o-net fuse goes from the jumper to the primary coil and may be removed and replaced with a shotgun hot stick.
With a loop system, you need an open point and to feed the loop from both ends. You need lightning arresters on both ends of the open point. The MV cable needs to be large enough to handle the total load of the loop. You need two qualified people to do any work on the system whenever any switching is done.
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