The next time you have a short service interruption or lights flicker, a life just may have been saved.
Any time an SVEC crew is hands on with energized equipment, it initiates what’s called the hot line tag process. If they are setting a pole, replacing certain pieces of equipment, such as cross arms and insulators, or pulling in new conductor, crews need to “tag” the line to ensure their safety. By controlling the line with this highly sensitive setting, crews have the peace of mind to do their job without additional risk.
“In the event of a fault, whether it is a squirrel contact or human contact, hot line tag will de-energize the line in approximately 40 milliseconds,” Manager of System Engineering Nathan Berry says. “This significantly reduces the amount of energy that a lineworker would be subjected to in the event of an inadvertent contact or equipment failure while working hands on.
“Without hot line tag it could take the line several seconds to de-energize, which would result in much higher energy and much higher danger and potential injury.”
For most of SVEC’s main lines, the hot line tag process starts with the crew leader calling the Operations Center.
“They will identify themselves, their work and the device they need hot line tag on,” Berry says. “Then the Operations Center navigates to that device in our system and with a couple clicks of a mouse, hot line tag is turned on.”
For tap lines – those that go to individual buildings or neighborhoods – the process is slightly different. The crew leader must drive to the device in the field, open the control box and push a button. The crew leader also communicates with the Operations Center to let operators know the device is on hot line tag, Berry says.
Crews’ safety is always the priority when there is a job to do. The trade off with hot line tag, as Berry notes, is when any fault on the line occurs while hot line tag is in operation. The line will de-energize until crews are verified safe and the line has been patrolled. A member may lose electricity or have blinking lights under these circumstances. One recent example was in Stuarts Draft in February, when contractors rebuilding an entire circuit initiated hot line tag and, while working, a squirrel came in contact with an energized line.
“When the line is on hot line tag, any fault causes the entire line to go out,” Manager of System Operations Bill Rees says. “An inconvenience, yes, but for safety reasons we need to have our protections set this way.”
Alternatives to hot line tag exist, such as de-energizing lines by backfeeding electricity from another location, to avoid the risk of members losing service or seeing blinking lights. Those options, however, are not always available.
“Backfeeding options depend on many factors like circuit compatibility, loading and switching device placement. In most cases backfeeding would just shift the problem to another circuit,” Berry says. “If there is a significant amount of line that needs worked that has no member connections, then backfeeding can possibly help.
“This was exactly the scenario in Stuarts Draft. There was nearly two miles of line that did not have any taps or transformers on it and we were able to backfeed the load further downline and completely de-energize a section of line.”
Members who have an outage caused by a hot line tag situation may notice it in the outage map on svec.coop or MySVEC app, where “HLT” sometimes appears as part of a description explaining the cause of an issue. The electric industry is ripe with acronyms. Only one, though, literally can be a matter of life or death.
“The biggest downside to HLT is it cannot distinguish between a squirrel contact and a human contact,” Berry says. “Our priority is to protect our workers. This is why we accept this downside. We want all of our crews to go home safely to their families.”