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pantograph / pulse timer
- Thread starter Sn00ze
- Start date
- Thread starter
- #3
Are the inputs coming from mechanical devices? Like valves or something? Maybe it's to allow for the mechanical motion to finish. 0.2 seconds would be way too long for coordinating electrical signals or a debounce. I consider a typical debounce setting to be somewhere around 4ms, at least in terms of whats acceptable for protections.
If it's in an area of very high electrical noise, and perhaps the grounding wihtin the plant isn't as good as it could be this could be a left over artifact from an older version of eletromechanical logic that made its way into the new electronic logic. Debounce (fancy way of saying delay) is often used to keep transient interference from causing a false pickup. Again, 0.2 seconds is VERY long for this, so I would guess its due to something mechanical.
Also, debounce is often used to deal with 'gremlins' or weird issues that folks don't have the patience to figure out. Transient problems on secondary systems can almost ALWAYS be solved by using proper grounding techniques.
If it's in an area of very high electrical noise, and perhaps the grounding wihtin the plant isn't as good as it could be this could be a left over artifact from an older version of eletromechanical logic that made its way into the new electronic logic. Debounce (fancy way of saying delay) is often used to keep transient interference from causing a false pickup. Again, 0.2 seconds is VERY long for this, so I would guess its due to something mechanical.
Also, debounce is often used to deal with 'gremlins' or weird issues that folks don't have the patience to figure out. Transient problems on secondary systems can almost ALWAYS be solved by using proper grounding techniques.
Skogsgurra
Electrical
The device you see on Railways. It pulls electricity from the carenaria, which see ![[bigsmile]](/data/assets/smilies/bigsmile.gif "[bigsmile] [bigsmile]")
Gunnar Englund
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.
Gunnar Englund
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.
Skogsgurra
Electrical
uh... locomotives, catenaria
Gunnar Englund
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.
Gunnar Englund
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.
- Thread starter
- #9
Haha Mark, that was my first thought too. They are not common at all.
I've basically only seen them at this particular substation because they make the footprint unimaginably smaller than regular subs and thus they would have to rebuild the substation in order to fit regular switches so they stick with these.
It is a single ploe switch so we are open/closing all 3 using a single signal from the control module. that's the only difference i can see from a regular airbreak switch which performs 3-pole opening.
To answer your question. As far as i can tell it trips the open/close coil as it would with regular switches but it does 3 instead of a coil. Which now that i think about, i think this might be done for single pole breakers?
About your comment on old electronics. No it definitely was not grandfathered in. It looks like they actually re-issued the construction prints to add this logic in there. Seems the regular control module was not sufficient for this style of switch.
I've basically only seen them at this particular substation because they make the footprint unimaginably smaller than regular subs and thus they would have to rebuild the substation in order to fit regular switches so they stick with these.
It is a single ploe switch so we are open/closing all 3 using a single signal from the control module. that's the only difference i can see from a regular airbreak switch which performs 3-pole opening.
To answer your question. As far as i can tell it trips the open/close coil as it would with regular switches but it does 3 instead of a coil. Which now that i think about, i think this might be done for single pole breakers?
About your comment on old electronics. No it definitely was not grandfathered in. It looks like they actually re-issued the construction prints to add this logic in there. Seems the regular control module was not sufficient for this style of switch.
Wow! Thanks for that video. I never would have guessed this was a power station application. Pretty crafty solution to limits of approach, however I'm not sure I would feel comfortable using that in a 500kV station - I like my switches as simple as possible (preferably war-time vintage hahaha). Can that switch open on pot or does the circuit have to be dead? I'm guessing the 'pulse controller' refers to some kind of pulse-width modulation for the motor?
The logic makes a bit more sense to me now that I can see the application. In fact, now knowing this is for a disconnect switch I'd consider adding additional time delay. Make sure this thing has nothing to do with your protections (ie: I wouldn't use its pallet's to do ANY primary protection supervision), although that type of logic looks like switching interlocks (good idea!).
Single pole switches will typically use the pallets of all three switches in the control circuit to basically mimic the same logic (opening/closing at the same time).
The logic makes a bit more sense to me now that I can see the application. In fact, now knowing this is for a disconnect switch I'd consider adding additional time delay. Make sure this thing has nothing to do with your protections (ie: I wouldn't use its pallet's to do ANY primary protection supervision), although that type of logic looks like switching interlocks (good idea!).
Single pole switches will typically use the pallets of all three switches in the control circuit to basically mimic the same logic (opening/closing at the same time).
Skogsgurra
Electrical
These are more like the original Panthograph - a device used to scale drawings. Before CAD.
Gunnar Englund
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.
Gunnar Englund
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.
- Thread starter
- #12
Mark,
yes. I just realized it is to keep the CCT energized for longer to give it time to open/close. It The yard run to the switch seems to be 100m on a #10AWG so i am a bit concerned about Voltage drop. i've yet to crack some numbers but I wonder if this ON time delay helps with that as well.
Skogsgurra, Yes i believe that's where the name for this switch came from. Which only added to the initial confusion haha
yes. I just realized it is to keep the CCT energized for longer to give it time to open/close. It The yard run to the switch seems to be 100m on a #10AWG so i am a bit concerned about Voltage drop. i've yet to crack some numbers but I wonder if this ON time delay helps with that as well.
Skogsgurra, Yes i believe that's where the name for this switch came from. Which only added to the initial confusion haha
Pantograph disconnector:
These are very common in Europe making up perhaps the bulk of busbar isolators. They is also have semi-pantograph and knee type isolators- the knee types are used occasionally in the US from my understanding- I think TVA uses them. The AC-DC-AC PSEG to ConEdison station to New Jersey is one US application of these disconnects.
These are very common in Europe making up perhaps the bulk of busbar isolators. They is also have semi-pantograph and knee type isolators- the knee types are used occasionally in the US from my understanding- I think TVA uses them. The AC-DC-AC PSEG to ConEdison station to New Jersey is one US application of these disconnects.
@Marks1080: They are usually designed to open on potential (capacitve charging current) and looped busbar transfer:
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