mbrooke
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- United States
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- Technician
What bus coupling configuration should I use for an HV/EHV GIS substation? I have lots of options but zero guidance as to what and why.
Bus Coupling Need Help
- Thread starter mbrooke
- Start date
- Status
- Location
- Tennessee NEC:2017
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- Semi-Retired Electrician
Oh, did you finally get a job with a POCO?
Just guessing and it's not my area of experitse (at least I qualified the statement).
Probably two distictly seperate problems or operational capacities:
1. The bus itself, lets says it's a single primary feed but a district loop that can be fed from either end. The POCO usually handles that and can sectionalize the bus for troubleshooting and uptime. Only one end is fed at a time, they can feed from either end, and they have one bus open point to avoid dual feeding but can sequentially change the bus open point to isolate the bad section of bus primary.
When I've seen this done they use load break elbows at the padmount transformer. They sectionalize the bus by pulling the load break elbows, but your drawings probably show this being done with the primary loop switch.
2. Would be the typical customer connection with redundancy, so it would be some type of main tie main with open transition switching and Kirk Keys. So you would have dual redundant load side connections with options (and prohibitions). 1. Main A and Main B closed with the tie breaker open. 2. Either Main A or Main B closed (not both) with the tie breaker closed.
Sometimes you can work the problem backwards. Decide first what you want it to do and then go looking for the option that does that. Instead of looking at all the options and trying to decide what best approaches (best fit).
Sorry, I cannot look at all the options and see what each does, or even guess. My guess would be that they are trying to solve two problems that usually occur seperately, 1. trying to sectionalize a single primary feed that is single fed but is a loop with feeds at both ends. and 2. The customer's dual redundant main connection to the bus.
One thing I do see is all the switching would be open transition with interlocks for one feed at a time, but redundancy for where the feed comes from, and capacity for sectionalizing around bad spots (to maintain only one bus feed at a time). Nothing I see there is dual fed simultaneously or with closed transition switching (just guessing again but that would be the first thing would inquire about).
Probably two distictly seperate problems or operational capacities:
1. The bus itself, lets says it's a single primary feed but a district loop that can be fed from either end. The POCO usually handles that and can sectionalize the bus for troubleshooting and uptime. Only one end is fed at a time, they can feed from either end, and they have one bus open point to avoid dual feeding but can sequentially change the bus open point to isolate the bad section of bus primary.
When I've seen this done they use load break elbows at the padmount transformer. They sectionalize the bus by pulling the load break elbows, but your drawings probably show this being done with the primary loop switch.
2. Would be the typical customer connection with redundancy, so it would be some type of main tie main with open transition switching and Kirk Keys. So you would have dual redundant load side connections with options (and prohibitions). 1. Main A and Main B closed with the tie breaker open. 2. Either Main A or Main B closed (not both) with the tie breaker closed.
Sometimes you can work the problem backwards. Decide first what you want it to do and then go looking for the option that does that. Instead of looking at all the options and trying to decide what best approaches (best fit).
Sorry, I cannot look at all the options and see what each does, or even guess. My guess would be that they are trying to solve two problems that usually occur seperately, 1. trying to sectionalize a single primary feed that is single fed but is a loop with feeds at both ends. and 2. The customer's dual redundant main connection to the bus.
One thing I do see is all the switching would be open transition with interlocks for one feed at a time, but redundancy for where the feed comes from, and capacity for sectionalizing around bad spots (to maintain only one bus feed at a time). Nothing I see there is dual fed simultaneously or with closed transition switching (just guessing again but that would be the first thing would inquire about).
romex jockey
Senior Member
- Location
- Vermont
- Occupation
- electrician
dunno what i'm looking at, but that bottom switch bothers me...... 
~S~
~S~
mbrooke
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- United States
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- Technician
Thanks for your input
You can do closed transition switching only if the busses are somehow connected connected together, the voltage between them would only be 100 volts.
FWIW, the bus typical has between 12-24 positions.
mbrooke
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- United States
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- Technician
dunno what i'm looking at, but that bottom switch bothers me......
This might clear things up a bit:
You have at two main busbars (bus one and bus two). Each bay has electrical access to both these busbars. On bay is dedicated solely to interconnecting these two bars via circuit breaker, called a bus coupling:
More critical stations will have a 3rd main busbar, and if breaker maintenance is needed without taking lines or transformers out of service an additional transfer bus may also be added.
mbrooke
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- United States
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Ok, so I made two sketches of what I have in mind to clear up confusion.
First option:
Second option:
Up close comparison of the two coupling schemes in debate:
Note: LAs, wave traps, ground switches and the like have been eliminated for simplicity.
- Location
- Tennessee NEC:2017
- Occupation
- Semi-Retired Electrician
mbrooke
Batteries Included
- Location
- United States
- Occupation
- Technician
I know you want to see breaker and a half, but thats not always an option. 
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