Looking for ideas from an Engineer

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C

CMU

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Here is the scenario:
We have many buildings on our property and All are supplied by two 5Kv sources (call them "A" and "B") . We have selector switches in the buildings to "select" which 5Kv feeder "A" or "B" we want the building to be on.
I have been installing metering at all locations to track buildings loads. These meters are on the load low voltage side of the feeders. ( Feeders go to selector switch then selector goes to transformer down to either 120/208 or 277/480) I have connected all these meters to Ethernet so I can track them thru a web page I have made.

The Main 5kv distribution also has a computer screen which I have on the network to monitor the main gear.

Everything works perfectly BUT I would like to figure out a way to remotely electronically monitor WHICH feeder "A" or "B" that the building is on. The only way We have right now is to physically go look at the selector switches. (They have a "mechanical flag" to indicate feeder "A" or "B")
Any suggestions would be appreciated if this is even possible. I have been looking for a 5kv current switch like a CT that I can remotely monitor but so far no luck. Forget anything physical like micro switches or proximity switches.

Any suggestions at all are greatly appreciated!
 
charlie b

charlie b

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My approach would be to try to talk you out of thinking you need to do this. I wouls start by asking you why you think you need this. What would you do with the information? What makes you believe you don't already have that information? These primary selectable switches don't switch back an forth on their own. Some person has to take manual action. That won't happen unless one or more people decide it is necessary and appropriate. Just make sure that you get the news. You can add a visual display to your web page, something that shows the switch leg in service and perhaps a note stating the last time it was transfered from the other leg.

This seems to me to be one of those circumstances in which a low-tech solution is all that is needed. I can't think of any operational or maintenance situations that could go arwy if they were planned on the basis of one switch leg being in service, and that information being based on your visual display, only to discover that your visual display was out of date and the other switch leg was, in fact, in service.
 
C

CMU

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The problem is that the powers that be often lose track of which position they are in. They handed Me their chart recently and I decided to "check" it. They had 5 buildings wrong and that is very bad when We do testing.
When that happens they want you to go around and manually check each building. We have about 50 buildings to check and some of the switches are in underground pits that are difficult to access. Oh and of course this only happens in the winter time when you don't want to be outside anyway.

I was just trying to come up with a way to "computerize" it so to speak and take the Human element out of it.
 
zog

zog

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Charlotte, NC
Add an aux switch to the 5kV selector switch. Depending on the switch model it may be an optional accessory that is easy to add.
 
C

CMU

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Interesting, I hope you are right but most of these selectors are 30 years old or older. Finding new add on parts may prove difficult.
 
petersonra

petersonra

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Northern illinois
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engineer
CMU said:
Interesting, I hope you are right but most of these selectors are 30 years old or older. Finding new add on parts may prove difficult.
Click to expand...

If you have to, you could put a limit switch on the handle itself so that in one position it is tripped. That would tell you what you want to know.
 
mgookin

mgookin

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Fort Myers, FL
Could you power an addressable something off each side right after the selector switch which says "I'm hot" or "I'm not"?

I'm not a PLC guy but I'd think it might be that simple. It could go via wi-fi and report to your webpage.
 
C

CMU

Member
zog said:
Not when you have millions of such parts in stock. What is the model of the switch?
Click to expand...

They are pretty much all the same. Old WLI switches now owned by Eaton. The switch has a disconnect in it, you turn it off then open the door. At the bottom is the selector to select feed A or B, then close the door and turn the switch back on.

Damper end switch sounds interesting but im not sure the selector moves enough to trigger it.
Yes you are 100% correct in saying the meters I installed can indeed monitor a set of contacts. That is how I planned to computerize it. I just need the set of contacts to monitor lol
 
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C

CMU

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cpinetree said:
Cheap wifi webcam pointed at the switch?
Click to expand...

I have actually considered this buying a cheap wifi camera and see how it works but the switches have a small access door which would have to be left open to "see" the indicator. Not a big deal until someone inadvertently closes it.
 
C

CMU

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mgookin said:
Could you power an addressable something off each side right after the selector switch which says "I'm hot" or "I'm not"?

I'm not a PLC guy but I'd think it might be that simple. It could go via wi-fi and report to your webpage.
Click to expand...

Thought of this too but it would have to go on the 5kv side since the low voltage side is common to both feeders.
To do that would involve 5kv to 120 control transformers much like a PT and with all the locations that would get costly quick.
 
G

GoldDigger

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If the aux contact does not pan out for any reason (and it is the simplest and most reliable), you could put CT coils on one conductor of each feeder and run them to relays or sensors.
It would only work if there was some minimum load on the feeder, but it would be better than nothing since you can already monitor the load.
 
C

CMU

Member
GoldDigger said:
If the aux contact does not pan out for any reason (and it is the simplest and most reliable), you could put CT coils on one conductor of each feeder and run them to relays or sensors.
It would only work if there was some minimum load on the feeder, but it would be better than nothing since you can already monitor the load.
Click to expand...

That is Exactly what I have been looking for. A 5kv current switch but it has to be the split type. I have a million of those for low voltage but nothing for 5kv that would snap around 500 kcmil.
 
J

jim dungar

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Wisconsin
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CMU said:
That is Exactly what I have been looking for. A 5kv current switch but it has to be the split type. I have a million of those for low voltage but nothing for 5kv that would snap around 500 kcmil.
Click to expand...
If your 5kV conductor is shielded, you can probably use any standard 'split core' CT. Most instrument transformer manufacturers have application notes on using 600V Cts on shielded conductors.
You might have some inaccuracy due to possible currents on the MV shield, but it seems you are only looking for more of a go-no go type of signal.
 
junkhound

junkhound

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Renton, WA
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EE, power electronics specialty
C

CMU

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Yes the 5kv cables are shielded and the shield grounded. I don't care about the currents but just if there is a current or not. Exactly.

Ir detection. Never thought of that. I will have to read up on that!
 
zog

zog

Senior Member
Location
Charlotte, NC
CMU said:
They are pretty much all the same. Old WLI switches now owned by Eaton. The switch has a disconnect in it, you turn it off then open the door. At the bottom is the selector to select feed A or B, then close the door and turn the switch back on.
Click to expand...

Those had an aux switch option that has 5NO and 5NC contacts, Eaton should still stock them, P/N 7278A27G28. What part of the switch drives the aux switch will determine if you can use it for what you want to do, would have to take a closer look at that. Should be easy enough to configure another aux switch off the selector switch if the standard option will not work for you.
 
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