With 1,400 circuit miles (2,253 circuit km) of transmission lines — many of which traverse difficult terrain — the (NYPA) is faced with the daunting task of inspecting these lines and reaching problem areas. As a way to confront these issues, the utility has begun looking at alternatives that are more efficient, more cost-effective and, in some cases, may obviate the need for linemen to scale a 200-ft (61-m) tower to perform a repair.
One potentially transformative tool NYPA is evaluating is the LineScout, . The LineScout is a robot that has been around in some form since 1998. Hydro-Québec first developed the robot following the notorious ice storm in January 1998 that left millions of people in eastern Canada, northern New York and New England without power for days. The goal was to use the robot to de-ice high-voltage lines. Since then, it has been developed further to perform inspections, check splices and make temporary repairs.
The LineScout has been used successfully by Hydro-Québec as well as National Grid in the UK and utilities in China. Recently, NYPA was the first U.S.-based utility to use the robot to test transmission line coating. For NYPA, a device that could transverse line and provide real-time information on conditions was intriguing. Therefore, a test was set up in the summer of 2015 near the utility’s St. Lawrence-FDR power project in Massena, close to the Canadian border, so NYPA engineers and researchers could see the LineScout in action.
NYPA is the nation’s largest state public power organization. On a given day, it provides 15% to 20% of New York’s electricity supply, most of it originating from large hydroelectric plants in Lewiston, near Niagara Falls — the state’s largest power plant — and Massena. NYPA has a strong record of reliability, but even the best-maintained assets show their age. For example, NYPA’s Moses-Adirondack line was built by the U.S. Department of Defense during World War II and acquired by NYPA in 1953. (A seven-year process to update the line will begin in 2016.)
From a cost and efficiency standpoint, it is easy to see why having the LineScout would be desirable, but there also are pragmatic considerations. The test of the LineScout was on NYPA’s Moses-Reynolds 3 line, which crosses the St. Lawrence River as it leaves the NYPA-St. Lawrence-FDR power project. There are many logistical concerns and cost considerations associated with making repairs on a line that runs over water. But sending a robot down the line to make a quick fix means resources and personnel can be deployed elsewhere.
Without such access, transmission managers, for example, first would have to wait for a helicopter to come back with its images. Then, after identifying problem areas, a crew would have to be dispatched — often to locations that are difficult to access and harder to fix — especially during the harsh winters endemic to upstate New York. Just because it is a right-of-way does not mean the repair can be made right away. LineScout has helped NYPA with this. The section LineScout examined on the Moses-Reynolds line, which has been in operation since 1958, turned up no anomalies.
The robot itself is fairly unassuming — nothing that would give a scare in a science-fiction movie. Weighing in at 247 lb (112 kg), it is only 2.8 ft (0.85 m) high and 4.5 ft (1.8 m) long. As it uses a pulley to glide along a line at 1 m/sec (3.28 ft/sec), its three-axis robotic arm grabs onto the conductors on a line bundle. One end of the arm has a high-definition camera that can be pointed in various directions, as dictated by the technician operating the LineScout from the ground using two joysticks. The pictures can be viewed instantly on a monitor while simultaneously being downloaded to a video file for future reference.
The other end of the arm is what the NYPA team was especially interested in because it is equipped with tools to perform detailed visual inspections using infrared technology that relays data to the ground. For example, an inspection can identify how much zinc coating remains on a line, which is especially useful in determining whether any maintenance issues may crop up sooner rather than later. It is the kind of information that would not be available following a helicopter inspection or during a line walk on the ground.
The LineScout also can measure the electrical resistance of splices as well as tighten or loosen bolted assemblies. However, NYPA was most impressed by its ability to make minor repairs. For example, it can apply a clamp to loose strands of aluminum fraying from a conductor, which in some cases, may be all that is needed. At the very least, it can limit a problem before a technician can be sent up to make a permanent fix.
With each iteration of the LineScout, IREQ’s team — led by Serge Montambault — has made the LineScout more nimble. It is not enough for the LineScout to roll down a line, especially when obstacles are in its way. The LineScout is able to clear vibration dampers, insulator strings and corona rings, among others. In turn, crews on the ground can get close-up views of buckles, turnkeys and bolts that otherwise would be unavailable unless a technician were to go up in a bucket. Even then, the technician’s eyes might not be as good as the camera. The LineScout can surmount obstacles as large as 760 mm (30 inches), and handle conductors with diameters 12 mm to 60 mm (0.5 inches to 2.4 inches) and splice sleeves with 25-mm to 85-mm (1-inch to 3.3-inch) diameters.
The LineScout is adaptable to different types of line. Technicians will first check diameter — for the conductor and splice — with regard to the wheel radius and to gauge. This is to ensure that the line’s mechanical strength can withstand the weight of the LineScout without damaging the conductor. This includes taking into account the sag variation if working on an energized line. Despite it being a relatively new technology, the LineScout can operate on optical ground wire (OPGW), ground wire and aluminum conductor steel-reinforced (ACSR) lines.
Beyond the efficiencies that can result from using a LineScout, one of the most important factors for NYPA in determining whether it will be employed is safety. Readers of this publication do not have to be reminded about the dangers of working on a transmission tower. Electrocutions, deaths from arc flashes and accidentally touching a line are rare occurrences. But utilities like NYPA look hard at U.S. Occupational Safety and Health Administration (OSHA) statistics, which reveal six utility workers were killed from 2009 to 2014. If someone does not absolutely, positively have to go up to check on a line, then the specter of filing an accident report is eliminated.
Even if an inspector or technician were sent up, the line would first need to be turned off and power, if possible, then rerouted. In contrast, the LineScout is designed to work on energized high-voltage lines. Still, the human factor very much remains part of the equation. Perhaps the LineScout will advance in future iterations where its operation can be fully automated. For now, though, it can ably serve as a complement to highly skilled crews.
Weighing the Considerations
NYPA is still assessing the long-term efficacy of the Line-Scout. The utility must weigh the cost of licensing the technology from Hydro-Québec and whether the condition of its lines would necessitate deploying the LineScout on a regular basis.
NYPA also is doing an extensive evaluation of unmanned aerial vehicles (UAVs) — or drones — as another way to inspect lines. It is working closely with the (EPRI) to evaluate which drone vendors would be most effective working near live lines. Like the LineScout, this is a technology whose potential first needs to be matched up with its actual application.
For example, standards for how close a UAV can get to a line need to be established. If an operator were to lose control of a drone and it flew into a line, repairs could cost far more than the savings envisioned by using a drone instead of a helicopter or line walk. Also, the effect of electrical and magnetic fields on the images the drone sends back — as well as how they affect a drone’s performance — must be studied.
It is conceivable a drone could work in tandem with a LineScout. The former goes up and spots a problem, which the latter is then sent to patch. Overkill? This is hardly the case when a utility has 1,400 circuit miles of transmission lines like NYPA or the 20,000-plus circuit miles of lines on Hydro-Québec’s network.
Such a combination may be far off in the future, but may not be as distant as utility traditionalists might assume. There are those who say the adage of “If it ain’t broke, don’t fix it” should apply to the inspection and repair of high-voltage lines. In other words, the way utilities have always done it has worked fine, so why mess around? The LineScout offers both a creative and compelling answer to that question.