Reply With QuoteWhen we are working live line we only have the circuits at the location we are at under hold off protection, I do not see the purpose of having the circuits on the other side of an open point under hold off protection.
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Distribution Automation
I am a former Lineman / Troubleman now Control Operator for a city utility that is putting into service a SCADA Controlled Distribution Automation system c/w S&C PME / Vista cubicles & ScadaMate switches in a 25KV Aerial / URD multiple circuit area where live line (rubber glove) work is routinely done on the aerial lines.
Our management & engineers feel that disabling the "auto restore" and applying a "HotLine" tag to the circuit being worked on is sufficient.
I DON'T agree with that !! The normal open points are between different circuits and it is my opinion that the N/O devices need to be treated as circuit breakers and as well as the "auto restore" function being disabled they should be tagged in SCADA and the ability of them being closed via SCADA should be disabled the same as a "HotLine" tag prevents the breaker from being closed via SCADA.
I would like to know how other utilities deal with these systems.
When we are working live line we only have the circuits at the location we are at under hold off protection, I do not see the purpose of having the circuits on the other side of an open point under hold off protection.
Last edited by lewy; 09-14-2008 at 06:33 AM.
Is this in a Distribution Automation system ?Originally Posted by lewy
In a DA system the N/O devices have the ability to "auto close" and or be closed remotely via SCADA
In our system when a crew books on to a circuit we apply a "HotLine" tag via SCADA, it does 3 things, blocks the reclosure , modifies the relay settings (faster trip @ a lower fault level) & prevents the breaker from being closed via SCADA.
Here is a link to the S&C DA info
http://www.sandc.com/products/intelliteam/default.asp
From A linemans perspective........
Keep in mind that a hold on a recloser is not designed to protect the worker, it is only required to have a recloser on one shot or non reclose when pulling conductor over another energized circuit according to OSHA.
That being said I see your concern of trying to protect the worker. I feel when doing hot work you must use proper work procedures and cover and maintain all min approach distance.
As a journeyman you should never rely on any mechanical electric device to protect you. Your work procedures and safety procedures and training is what you should rely on.
Just my 2 cents, good luck tryin to change it.
Last edited by johnbellamy; 09-13-2008 at 06:03 PM.
Scada
Here is an argument for leaving a SCADA recloser on supervisory control. If god forbid something should happen, and the recloser fails to operate, which they can, SCADA allows a lineman to call area dispatch and have them remotely open the circuit. This saves time in performing a rescue in that the crews involved don't have to drive all the way to the recloser to open the circuit on which they are working. Another instance in which it can aid a lineman, is if an outage occurs while work is being performed, such as reconductoring, the line can quickly be reenergized by a call to area dispatch. I have a great deal of faith in the people at my company who are in control of SCADA. They are very professional and competent people, they would never reenergize a line without being in contact with the person who put the DNR tag on. That being said, John is right, reclosers are for equipment protection. They are not a replacement for good work practices. If they work correctly however, they do add one more layer of protection.
Re SCADA
I climbed my first power pole in 1972, did live line work (rubber glove) for several years, was a troubleman for a few years and for the last 4 years or so am a control operator. I agree that the best safety is to do the work properly and safely. When we did hot line work the only time we blocked a re closure was when pulling in or out wire over or in the area of energized conductors. Our safety and management people decided that HotLine Tagging is required a few years ago. One of the reasons is that due to the modified relay settings the "Arc Flash" is limited. I am not sure if is law yet but to comply to the "Arc Flash" standards the linemen would either have to wear something resembling bomb suits or have "HotLine" tags to do live line work. The "HotLine" tag does not prevent an operator from opening a breaker it blocks the close only. It is our procedure that if a crew asks for a circuit to be dumped, we dump and ask why later.
My concern with the DA is that in one case a crew can be booked onto a circuit that can be automatically or remotely re-energized from 3 NO tie points that are on 2 different circuits. Disabling the "Auto Restore" solves one of the problems but I think that the devices should also have the remote close blocked & tagged in SCADA.
This system is new to us but they are out there and I am wondering how other utilities deal with them.
I know you were a lineman......
Alot of SCADA out there these days, sounds like the system your on is pretty up to date having the capabilities to close normal opens on distribution, Transmission is pretty common.
The fancier the systems the more that can malfunction, especially if its new before you can work the kinks out.
I am not arguing about any added work procedure your company enforces, I am just tryin to make the point that flashes happen when things go wrong, I would just add that if guys can really focus on that second point of contact, and cover or Isolate so they are not anywhere around that flash.
I hope the folks you work for will listen to your concerns and you can get things changed, I personally like to disable scada and put the controls to local, it dosen't bother me if the outage takes a few more minutes, people will survive.
It's a valid concern
If your working on a circuit the for which you have requested non reclose assurance. You should have that NRA tags in pllace not only at the feeder breaker but at other open points {SCADA} that could close into the work area. Hot Line Tag protocall at all locations of possible reclose.
"Restoration of service after automatic trip. When circuits or equipment upon which tags have been placed open automatically, the circuits or equipment shall be left open until reclosing has been authorized."AKA You can't by NESC code close into the tagged work area from a different direction.
Here is how it reads in the National Electrical Safety code:
442. Switching control procedures
F. Restoration of service after automatic trip1. When circuits or equipment upon which tags have been placed open automatically, the circuits or equipment shall be left open until reclosing has been authorized.
2. When circuits open automatically, local operating rules shall determine in what manner and how many times they may be closed with safety.
Last edited by CPOPE; 09-14-2008 at 05:51 AM.
I have a few questions on how the systems work down there
If you are working on a circuit does the other circuit at he open point automatically close if you loose the circuit you are working on?
Do these scada contolled switches close on there own without anyone telling them too?
We also have scada & we only place the circuits at our work location under non reclose, but the operator also know that if we loose a feeder they just do not start closing in the open points.
CROPE
In my opinion a "Re close Block" does one thing. Prevents an auto reclose.
A " Hot Line Tag " does 3 things Prevents an auto re close, modifies the relay settings and prevents a close via a SCADA command. (read operator error).
In a DA system as I said in a previous post we have one situation where as well as the main feed from the sub station there are three N/O points fed from two different circuits in the field with devices that can auto close and / or be closed via SCADA. I don't think that applying a Hot Line Tag to the Main feed and disabling the Auto Restore complies to the Hot Line Tag standard.
The utility that I work for is like most these days run by accountants, clerks and engineers most of which don't have much of a grasp of how power line work is done, it's all about numbers.
LEWY
FYI I am located in Western Canada. A DA system is designed to minimize outages. If their is a fault in one of the zones the system isolates the zone and restores the rest of the circuit from alternate sources automatically. The utility I work for has big plans for this. Its complicated, its new to us, there will be bugs to work out. I want to do the best that I can (with my limited influence) to ensure that we have done every thing that can be done for the safety of our crews when they are working in this system. All of the planning / engineering to date seems to be focused on outage minimization not daily, practical operation.
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