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1007Control
09-13-2008, 04:33 PM
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.

lewy
09-13-2008, 04:43 PM
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.

1007Control
09-13-2008, 05:07 PM
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 under hold off protection.

Is this in a Distribution Automation system ?

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

johnbellamy
09-13-2008, 05:49 PM
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.

mainline
09-13-2008, 06:23 PM
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.

1007Control
09-13-2008, 07:02 PM
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.

johnbellamy
09-13-2008, 07:19 PM
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.

CPOPE
09-14-2008, 05:43 AM
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 trip

1. 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.

lewy
09-14-2008, 06:32 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.

1007Control
09-14-2008, 08:17 AM
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.

CPOPE
09-14-2008, 08:59 AM
I got you on the differance between Hot-Line-Tag and non-reclose. Understand that only newer equipment has the hotline tag feature.

Your situation needs a code based argument to your management engineers and accountants. Goes like this. We have a feeder breaker and three normal open points. Automatic restoration scheeme is enables such that we have 4 possible sources to be disabled non-auto and tagged via scada by the way I read NESC.

NESC 442F requires for the protection of the field worker the circuits or equipment shall be left open until reclosing has been authorized.

Refer to rule 442E for the tagging requirement. If I'm working on a line and there are 4 possible divices that can auto reclose back into my work area I need to tag up all 4 devices by code. Take note on the exception as to this is how the hotline tag protocal via SCADA fits in.

442. Switching control procedures
E. Tagging electric supply circuits associated with work activities

1. Equipment or circuits that are to be treated as de-energized and grounded per Rule 444D shall have suitable tags attached to all points where such equipment or circuits can be energized.
2. When the automatic reclosing feature of a reclosing device is disabled during the course of work on energized equipment or circuits, a tag shall be placed at the reclosing device location.
EXCEPTION: If the automatic reclosing feature of a reclosing device is disabled by a Supervisory Control and Data Acquisition System (SCADA), the system shall provide for the following:
(a) At the SCADA operating point
(1) A signal is received by the SCADA operator confirming that the disabling operation has occurred at the reclosing device location, and
(2) A readily visible tag or electronic display is used to inform any potential SCADA operator that a disabling operation has been initiated, and
(3) The tag or electronic display is removed before action is taken to re-enable the automatic reclosing feature.

(b) At the reclosing device location
(1) The reclosing feature is disabled in such a manner as to prevent manual override of the normal control by any potential on-site operator, or
(2) A signal, flag, or other display is used in such a manner as to alert any potential on-site operator that the reclosing feature has been disabled.
3. The required tags shall be placed to clearly identify the equipment or circuits on which work is being performed.

lewy
09-14-2008, 09:42 AM
We all have different work protection codes , In Ontario 90% of the province uses the same code, but I am sure they are different from province to province & state to state maybe even company to company. Anytime we are working live line the operator knows what circuit we are on & if there are any other circuits at that location & again they would be under hold off protection. Obviously if that feeder tripped the operator is going to get in touch with the person or persons who are holding the protection, they are not going to start closing the breaker or the open points, that is why I do not see the point of having all of the other feeders at the open points under hold off. Would you go around & tag all of the open points that are not under scada control?
A little different angle do you have all of the feeders at the open points under hold off protection when working on a de-energized line, we do not ,but I think it would make sence no use testing your grounds more than 1 time.

mainline
09-14-2008, 10:01 AM
I see as usual that Maine is way behind the curve on some things. All SCADA at my uitility is controlled by operators. We do not currently (as far as I know) have any distribution automation that will perform switching to close n/o. Most of that is still done manually using gang operated switches or operator switches. If I am understanding the way it works where you are, I too would be very leery of working on a system where a computer could switch and close n/o to restore power. That could lead to some nasty incidents.

1007Control
09-14-2008, 10:53 AM
CPOPE

Thank you for the regulation, I am not sure that there is a similar Canadian reg., I have been looking.

LEWY

In our transmission system manual disconnects are "Opend Locked & Tagged" our motorized disconnects are Opend via SCADA then "Locked & Tagged in the Local Position & the DC fuses pulled" to isolate a de-energized line.

Like most other places at our utility most of the really experienced people have retired and the few that are left have one foot out the door. The systems are getting more complicated every day, Anything that can be done to prevent a system malfunction or an operator error (we are human) from becoming a Mistake with Consequences must be done.

I will have to leave this discussion for a while, I start my night shifts in a few hours.

lewy
09-14-2008, 11:36 AM
CPOPE

Thank you for the regulation, I am not sure that there is a similar Canadian reg., I have been looking.

LEWY

In our transmission system manual disconnects are "Opend Locked & Tagged" our motorized disconnects are Opend via SCADA then "Locked & Tagged in the Local Position & the DC fuses pulled" to isolate a de-energized line.

Like most other places at our utility most of the really experienced people have retired and the few that are left have one foot out the door. The systems are getting more complicated every day, Anything that can be done to prevent a system malfunction or an operator error (we are human) from becoming a Mistake with Consequences must be done.

I will have to leave this discussion for a while, I start my night shifts in a few hours.

We do the same on our motorized switches, but not when working on energized lines.& again we would not have hold offs on the other sides of the open points

1007Control
09-14-2008, 03:57 PM
LEWY

In our distribution system we Hot Line Tag the breaker via SCADA the normal open points up until now have been manually operated and not an issue. Now that in this one area we have a DA system the N/O points in that area are an issue.

We operate 138 / 240 & 500kv switch yards that are tie points with the Provincial Grid. When the transmission utility needs to isolate a line to do Dead & Grounded work on a line between our switch yard and theirs we provide them with isolation from the disconnects and block & tag the re closure at the switch yard (not by SCADA) , tag the local control handles of the associated breakers at the yard and apply "NO CLOSE" tags to the breakers in SCADA. I don't know if this is to comply with a Utility Regulation or just their own standard. They ask, we do it for them.

Stinger
09-14-2008, 04:11 PM
I know that NSTAR is using the SCDA now. We as contractors have been putting them up. The one thing that bothers me about them it is hard to see if it closed or open at night because the colors are hard to see from the GRD. At least the old GOAB's you can visibly see if the are open or not. As one of our brothers stated nothing takes the place of good safe line work and job planning. Some systems are so old or overloaded you can not get DNR.

Also, MAINLINE if you read this I feel very safe with CMP lock out/tag out hold and the DNR procedures you have in place.

lewy
09-14-2008, 05:45 PM
LEWY

In our distribution system we Hot Line Tag the breaker via SCADA the normal open points up until now have been manually operated and not an issue. Now that in this one area we have a DA system the N/O points in that area are an issue.

We operate 138 / 240 & 500kv switch yards that are tie points with the Provincial Grid. When the transmission utility needs to isolate a line to do Dead & Grounded work on a line between our switch yard and theirs we provide them with isolation from the disconnects and block & tag the re closure at the switch yard (not by SCADA) , tag the local control handles of the associated breakers at the yard and apply "NO CLOSE" tags to the breakers in SCADA. I don't know if this is to comply with a Utility Regulation or just their own standard. They ask, we do it for them.

I am going by your original post which was 25 kv . I have only worked distribution so I cannot really comment on the transmission side, but again as far as distribution I do not see the need for hold offs on the other side of the open point when doing live line work.

1007Control
09-14-2008, 06:26 PM
I am going by your original post which was 25 kv . I have only worked distribution so I cannot really comment on the transmission side, but again as far as distribution I do not see the need for hold offs on the other side of the open point when doing live line work.

LEWY

I am not suggesting that we put "hold offs" on the other side of the open points. I am saying that the N/O points (PME / VISTA cubicles & ScadaMate sws) that have the ability to "auto close" and or be closed by a SCADA command need to be properly disabled & tagged in SCADA.

I'm off to work, will try to check in tomorrow.