Starting this thread as not de-rail another one. How do you guys set the reclose logic for two terminal 69 and 115kv lines with non communicating, non PLC relays? The desired outcome is to have only one relay do a single reclose attempt after 30 seconds, and once the line holds for 20 seconds have the other relay close its breaker after a sync check. Ie, have the remote relay not reclose but also not lockout.
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Relcosing logic for 311C 1
- Thread starter Mbrooke
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I also hear they have problems with people stealing PCB oil, because they hear it is good for their skin.
The connections with Mexico are not that major, in that it only includes Baja Mexico, and not the whole country.
I was not even aware they use 60 Hz until a number of years ago.
The connections with Mexico are not that major, in that it only includes Baja Mexico, and not the whole country.
I was not even aware they use 60 Hz until a number of years ago.
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- #42
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- #44
Is is, and then abruptly changes to 50Hz south of Brazil. Jamaica is 50Hz when you would think it would be 60Hz.
Although to be honest I prefer the sound of 50Hz to 60Hz.
Although to be honest I prefer the sound of 50Hz to 60Hz.
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- #45
This might be for a new thread- but want to re-use this one since its along the same lines.
Does anyone know how to set the logic such that re-closing is blocked for zone 2 and zone 3 faults but proceeds as normal for a zone 1? This would hold for both positive sequence MHO and ground quad elements in regard to their respective zones.
I checked the manual but it only mentions 3 phase faults as follows:
Does anyone know how to set the logic such that re-closing is blocked for zone 2 and zone 3 faults but proceeds as normal for a zone 1? This would hold for both positive sequence MHO and ground quad elements in regard to their respective zones.
I checked the manual but it only mentions 3 phase faults as follows:
davidbeach
Electrical
I've no idea why you'd want to do that, but it would be really easy.
First set the zone 1 common timer to 0, not OFF. Then 79DTL would be TRIP * !Z1T.
I've seen too many instances where relays over trip for what ever reason to not want every distance element trip to reclose. But this is far from the first time I've seen the idea of only reclosing on zone 1, so maybe I'm missing out on something.
What about faults toward the remote end of the line for which zone 1 never picked up? How well do all of your zone 3 (probably really zone 4 if you're using SEL relays) elements coordinate? That is, how well do they continue to coordinate as tripping progresses? What looks to coordinate before the first trip may not, or conversely, what looks not to coordinate at all prior to the first trip actually coordinates perfectly well afterward. Personally, I'd be more worried about not getting the reclose on an over trip than having a zone 4 operate twice.
First set the zone 1 common timer to 0, not OFF. Then 79DTL would be TRIP * !Z1T.
I've seen too many instances where relays over trip for what ever reason to not want every distance element trip to reclose. But this is far from the first time I've seen the idea of only reclosing on zone 1, so maybe I'm missing out on something.
What about faults toward the remote end of the line for which zone 1 never picked up? How well do all of your zone 3 (probably really zone 4 if you're using SEL relays) elements coordinate? That is, how well do they continue to coordinate as tripping progresses? What looks to coordinate before the first trip may not, or conversely, what looks not to coordinate at all prior to the first trip actually coordinates perfectly well afterward. Personally, I'd be more worried about not getting the reclose on an over trip than having a zone 4 operate twice.
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- #47
David Beach said:
Oh, that is easy!
In a system with none communicating protection relays a Zone 2 pickup can either be a line fault on the far end or a bus fault with a simultaneous stuck breaker at the receiving station. If the latter it is generally a good idea not to reclose onto a faulted bus. Now with communicating relays a failed breaker during a bus fault can send over a DTT to the sending station preventing a re-close. In such a system (with communication) relcosing one both zone 1 and zone 2 can be done without worry.
I am sure there are other reasons out there, but in my case this is the primary driver not to reclose on zone 2.
In such a system both 311C (or both 421) relays have a single re-close enabled on Zone 1. Which ever relay picked up zone 1 will reclose 15 or 30 seconds latter, and if the re-close is successful the relay on the other end which picked up on zone 2 will re-close after a synch check (hot line, hot bus). If both ends pickup on zone 1, then one end will reclose after 15 seconds and then the other after 30 seconds regardless if the first relay was successful or not at re-closing.
I know this sounds messy, but in a none communicating system its often a compromise.
In my world if a a relay trips on zone 3 (zone 4) this would indicate a serious problem such failed relaying at a remote substation. There of course could be a high Z fault out on the line, but the concern is generally not great enough to consider reclose.
Of course zone 3 trips can occur if a line is heavily loaded, however this would be mitigated via load shedding or generation re-dispatch before zone 3 elements (or over current elements) pick up.
Generally speaking a system which can tolerate a 30 second reclose delay via 3 pole tripping (vs needing single pole high speed auto reclosing) indicates a strong system with many other paths in the flow-gate. Thus biasing a system for dependability rather than security presents no major risk to losing load and is considered good practice. A line or element failing to trip, or a bus fault reclose, take more concern.
Though I do hear you, and your concerns are valid none the less.
davidbeach
Electrical
In that case my very simple equation won't do what you want. What you'll need is something in the reclose supervision equations that will allow a reclose into a dead line following a zone 1 trip but then require the line to come hot prior to allowing a reclose for any other trip. That probably takes a logic variable or two so that you get the right conditions.mbrooke said:
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- #49
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- #51
Thanks, will use that when the opportunity comes up.
A hypothetical what if... does not mean I will do it that way. What if I just kept things close to the factory settings so the speak, giving both relays a single reclose attempt (15 sec for one 30 for the other) and not bothering to to stop reclose on zone 2 and zone 3?
A hypothetical what if... does not mean I will do it that way. What if I just kept things close to the factory settings so the speak, giving both relays a single reclose attempt (15 sec for one 30 for the other) and not bothering to to stop reclose on zone 2 and zone 3?
davidbeach
Electrical
If you're doing the 15 & 30 routine, you could have the 15 sec end close regardless and have the 30 second end only close into a hot line. That makes things relatively simple. But why 30 seconds? If one end closes at 15 seconds and holds for even a couple of seconds it's probably going to hold for 30 seconds; where we have different speeds, and the slow end only closing to a hot line, we wait a whole 30 cycles between the first close (will trip instantaneously on SOTF if the fault is still there) and the "slow" end closing.
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- #53
Just values that feel "right" I guess, and in the event the fault is of such type that it does not flash over immediately. There are some fault (which involve tree branches for example) where the branch across the line will steam, flash-over, and then steam again for a few seconds after reclose before flashing over into an arc. The idea is to make sure the line will truly hold, and that all elements be it zero /negative sequence inverse time over current and impedance elements have a chance to pickup.
Here is one example of steaming before flashing over:
Here is one example of steaming before flashing over:
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