Physical Separation of Primary and Secondary Relaying

[electricnewbie]

I am curious to see how other people incorporate physical separation in primary and secondary line relays, I'm not talking about separate DC, CTs, etc.

On 115kV to 230kV transmission lines, is it necessary to use different panels?

If the two relays are on the same panel, is it best to put one close to the top, and the other closer to the bottom, or is it ok to put one close to the other?

Is there any US codes or guidlines that one can follow regarding this subject?

Thanks for the help!

 

[oldfieldguy]

Big utility company in the southern part of the US puts them both on the same panel section, primary on top.

old field guy

 

[bacon4life]

We have ours pretty close together on the same panel.

 

[DTR2011]

on the project I am on, there are 2 rows of panels - North and South. The Primary is on North Panels, Secondary on South.

 

[marks1080]

From the point of view of someone that works in the field I feel that the two should be as far apart as practically possible. Certianly not on the same rack. You will find there will be more inadvertants if you put them on the same rack. Very poor design.

 

[potteryshard]

I would come down on the side of having the primary and secondary relaying on the same panel; from the standpoint of the users, I would tend to think that having the controls, targets, displays, et al relating to one given line or breaker physically located in two different places would invite error.

I would agree that some physical separation on the panel is not a bad idea, but I've always maintained that confining one panel to the control and protection of one bay helps to promote a better mental picture of the overall scheme. (The word 'bay' is used as with a ring or breaker-and-a-half scheme, to control or protect that line or transformer in that bay will require interface with two breakers.)

 

[marks1080]

Also consider other issues. If your building roof leaks water do you really want water running down a panel for both A&B protections?

Depending on where you are and the system involved physical seperation is a requierment.

 

[davidbeach]

Separating the protection of a line or transformer into two or more nonadjacent racks or panels is going to provide operational nightmares. You want to be able to tell the status of all of the protection for a single position from a single location. It would also be nearly impossible to upgrade the protection of one position while leaving everything else in service if there are shared racks/panels and nobody I know of has the money or space for two racks per position.

Sure there may be some advantages for separating them as outline above, but the disadvantages far outweigh the advantages.

 

[slavag]

Hi.
It's depend on the voltage level and size of transformer or generator.
From the 400kV we usually use only two separated panels.
For the AT or T from 250-300MVA, separated paneles, same for generators.
220kV or 330kV line protection, is depend on the rules of company.
I don't like use today words : primary and secondary, prefered Main1 and Main2, lot of cases is fully dupicated scheme, for generators and transformers.
For line is 87L with 21 bacj-up and 21 with communication, etc...

 

[marks1080]

david - are you talking about the separation of A&B protections or seperating protection racks of adjacent elements?

How is it more expensive to separate A&B protections? Especially if you are bringing all your cables to cross-tie racks? I see no issue with future upgrading of protections there.

There are pro's and con's with having A&B prtoections for the same element on the same rack. We have stations with both set ups and historically most inadvertants have happened on those racks that have A&B elements located on the same panel or adjacent to each other.

 

[davidbeach]

I'm talking about the A&B protections. Field connections for a position come into the rack/panel for that position. I can picture what a cross-tie rack might be and it just shouts of more failure points, particularly for CT circuits, the fewer points a CT circuit is terminated the better. Historically dual CTs haven't been available in many cases so the relays share the CTs. Separate locations in the control house make that rather difficult. Which relay location would get the control switch? Why would you make it easier for operators to miss something during an event by spreading out the necessary information all over the control house?

Yes, there are common mode failure risks associated with having all the protection for a position in the same rack, but the day-to-day reliability impacts of spreading the protection around the control house carries far more risk.

All that to say nothing of old installations where positions get upgraded protection one at a time over the course of years and any attempt to spread it around makes for logistical nightmares.

 

[jeffreed]

What are the chances that something bad could happen to both A & B in the same panel? Is there a NEC code for the separation?

 

[mgtrp]

NEC, like most codes, probably doesn't apply to an HV utility installation.

The design we have used in the past is both relays in the same cabinet, with a dubiously-fire-rated (no formal rating, but it might hold for a bit...) separator dividing the cabinet in two. Wiring for A protection up one side, wiring for B protection up the other and following disparate routes to the extent practicable out to the CT's, VT's, circuit breakers, etc.

 

[cranky108]

I've seen seprated primary and secendary panels, but it was interesting that they had common points in the control panels, and cable termination panels. So it diden't make since, other than it allowed more space for the electromechinical relays.

I've also seen seprated cable trenches in a substation, but I've never seen both in the same substation.