Canadian utility uses helicopters, a new fall-protection device and cameras to safely and efficiently patrol its lines.
Since 1949, linemen have relied on helicopters to inspect and maintain the transmission and distribution system for Hydro One, formerly Ontario Hydro. The fleet provides invaluable support for the growing demand of Hydro One's expansive, and sometimes inaccessible, power grid.
For about three decades, the utility hoisted its linemen to the top of its transmission structures using Sikorsky S58T helicopters. In modernizing its fleet, the company then moved to an AS 332 twin-engine Eurocopter Super Puma helicopter for hoisting applications.
After selling the Super Puma helicopters, Hydro One searched for a safe, efficient and effective way for its linemen to access the top of its transmission towers. That's when the utility first begun to integrate the Eurocopter AS350 Astar series into its fleet.
Taking Linemen to the Top of Structures
The helicopter operations team then came up with the idea of an enplaning and deplaning device attached to the helicopter. About 10 years ago, a team of pilots, linemen, work methods group, safety team and engineers developed the protocols and procedures for a custom-built AirStair device. This two-step device features handrails attached to the side of the helicopter. The helicopter can then hover in close proximity to the top of transmission towers, enabling the linemen to readily transfer from the hovering helicopter to the top of the transmission tower. The Astar helicopter allows up to four linemen to be on board at any time, and it features a stable center-of-gravity platform with powerful, reliable engines.
Before Hydro One invented the AirStair, the utility relied on large machines, which winched the linemen on to the structures. These machines were costly, and Hydro One wanted to find a less expensive and more efficient way to deliver linemen to their work locations. Over the years, the AirStair program has become a safe and effective tool for providing access to Hydro One's 30,000 circuit km (18,641 miles) of transmission lines.
The AirStair, which is only used by Hydro One, is compatible with the Eurocopter Astar series helicopter. This device allows the linemen to board a helicopter with all of their equipment, thus reducing about 50% of the climbing required.
Using the AirStair, Hydro One is able to improve significantly the productivity of the linemen. For example, the Hydro One linemen used the AirStair to test a string of six insulators on a double-circuit 500-kV corridor. The pilot delivered three two-member teams of linemen to the peak of the structures. By the time the pilot delivered the third team, he landed and shut down for a short period. Using radio communication, the first team notified him that they were going to be ready for a pick up. He then powered up the helicopter, picked up the first team and moved them to the structure next to the third team. The helicopter then kept leapfrogging the linemen down the line until the job was completed.
With this type of project, it wouldn't have been cost-effective to achieve the objectives in the given time frame without the use of the AirStair. Through a coordinated effort, however, the line crews and the helicopter pilot were able to achieve objectives in a reasonable time frame. Without the AirStair, the teams would have had to exert more physical effort and spend more labor hours to get the job done.
By using helicopters outfitted with the AirStair, Hydro One has been able to assist with customer satisfaction. Part of the company's assets are located in remote regions, which are difficult for the linemen to access. Hydro One's transmission circuits also cross through southern Ontario, which is heavily covered with agricultural fields. If the crews drive their vehicles through grain and corn crops, then the utility is responsible for covering the damage. By using helicopters, however, Hydro One's linemen do not set foot on the ground in these sensitive regions.
With the AirStair, Hydro One has adopted existing line procedures to change insulators on transmission structures for suspension and dead-end applications. This reduces the requirement to access the structures from the ground, which eliminates the need for vehicles and ground crews.
In Search of Fall Protection
Since Hydro One developed the AirStair, linemen have used the device for a variety of applications. The challenge with this in-house proprietary technology, however, was that when using the early version of the AirStair, linemen were not connected to either the helicopter or to the structure for a period of five seconds or less.
Linemen must not be anchored to two different objects at the same time. For example, if they are attached to both the structure and the helicopter, they could be in danger if the helicopter suddenly needs to depart in an emergency.
While attending an international conference back in 2002, Hydro One came upon the Wishbone safety device from Wishbone Safety. The AirStair team at Hydro One (which was then called Ontario Hydro) reviewed the safety device. Its work methods group also tested the device to ensure that it met company standards, which led to the company-implemented field trial.
By the end of the field testing, the company was satisfied and confident that the safety device would allow the linemen to be safely belted to the helicopter and the structure at the same time with a safety breakaway. It also would eliminate the time in which the linemen were not belted.
Making Modifications
With its high utilization of the Wishbone, Hydro One found ways to improve the product. The company worked with the manufacturer to enhance the safety device. For example, Hydro One asked the company to outfit the Wishbone with large red webbing for clearer attachment-point identification, an improved hinging mechanism and an enhanced safety snap.
To use the Wishbone, the linemen connect the device to their tower harness and to a travel-restrict lanyard from the inside of the helicopter. When the helicopter gets in close proximity to the top of the transmission tower, the lineman bonds to the shield or earth wire to drain the induction built up in the helicopter. At this point, the lineman attaches a fall-arrest lanyard to the structure. They are then connected to both the helicopter and lanyard at the same time with the built-in breakaway feature.
The primary reason why Hydro One opted to go with the Wishbone is that it features this unique breakaway mechanism with an advanced hinge. This allows the lineman to not fall and to stay safe in the event that the helicopter has an emergency and needs to depart immediately from the transmission structure. Then the lineman can remain on the transmission structure while the pilot addresses an emergency situation.
Daily Use and Maintenance
Before linemen use their Wishbone safety device for their daily work, they inspect and maintain the product. Hydro One's linemen are responsible for the care and condition of all their safety devices, including the Wishbone, and they are expected to return to the helicopter crew at the end of each day to maintain control over these specialized pieces of equipment. Then each morning, the Wishbone is again distributed to the linemen for the day's work program.
On any given AirStair program, Hydro One may have 12 to 15 linemen working, and each of these linemen require their own Wishbone safety device for enplaning and deplaning. The utility has two AirStair devices within its company, and 30 to 40 Wishbones that are actively in use. Over the last eight years, Hydro One has trained more than 200 linemen and carried out about 20,000 safe ons-and-offs using the AirStair and the Wishbone safety device.
By integrating both the AirStair and Wishbone into its helicopter program, Hydro One has been able to safely access the tops of transmission structures in its service territory. The company also has eliminated the short gap of time in which linemen were not belted to the helicopter or structure. With this new type of fall protection, linemen can work more efficiently and more safely while up in the air.
John Bosomworth (john.bosomworth@hydroone.com) is the chief pilot for Hydro One in Barrie, Ontario. He has been a pilot for more than 38 years and has accumulated more than 16,000 helicopter flight hours. He has been with the company since 1986 and is now responsible for the safe operation of the fleet of eight helicopters for the utility. He was also the individual who came up with the initial concept for the AirStair.
Derrick Brydges (derrick.brydges@hydroone.com) is a regional line maintainer and Level 2 thermographer for Hydro One. He is stationed at Essa Transformer Station and has been with the company for 35 years. In 1991, he was recruited to join the traveling crew and become part of the Thermovision program. Over the past 20 years, he has performed the Transmission Thermovision program. Brydges helped upgrade Hydro One's transmission lines' geographic asset data with digital imagery and video. In addition, Brydges was very involved with the development of the AirStair at Hydro One.
Hydro One Leverages Power of Helicopters to Improve Reliability
With the proper fall protection and technology, Hydro One's field workforce not only can maintain the lines, but also perform infrared scanning and mapping from helicopters.
With the infrared scanning and GIS programs, Hydro One has been able to minimize outage times and improve power reliability. Here are three key ways that the utility is leveraging helicopters in the field.
- Detect heat variations
Since the 1970s, Hydro One (Ontario Hydro) has used helicopters for infrared scanning on the transmission system. Infrared scanning is a noncontact, nondestructive way to detect thermal anonomalies on an electrical system. Through Hydro One's Thermovision program, thermographers can detect these anomalies so they can be repaired before a failure occurs. A planned outage can be repaired at 25% of the cost versus an unplanned outage.
To find the anomalies, a thermographer must first detect heat variations so they can be repaired before failure. Derrick Brydges, a thermographer and trained lineman, works with his team to follow the high circuit loading when looking for outages. In other words, in the wintertime, they may patrol the northern part of the province because of population heating loading. In the summer, they try to focus on the southern air-conditioning loading.
- Map the transmission system
In addition, Hydro One is also using its helicopters for its geographic information systems (GIS) program. In 2002, the utility acquired a transmission line geographic system from an external provider who mapped out the utility's entire grid system. The vendor filmed all circuits and took a captured image of every structure. With accurate information, the linemen no longer need to drive out to a structure or fly over it with a helicopter to view asset detail. Instead, they can bring up a structure on a computer to determine its characteristics, such as its design and component detail.
Hydro One is continually performing major maintenance programs on its wood poles due to wood rot and woodpecker damage. As a result, linemen have changed many structures over 20,000 km (12,427 miles). To provide current data on these assets, Hydro One has designed its own in-house GIS update program resulting in substantial cost savings.
Three Hydro One employees designed a way to update all of the data on the circuits with the most maintenance activity over the last decade. The GIS team uses a 10-megapixel Sony digital camera encased in a Polytech External Gimbal along with a Sony digital video camera and a Flir infrared camera system. As they fly the line, they take the digital imagery, save it on a disc drive and then submit the files to the GIS department, where the records are updated. Every year, Hydro One is replacing wood pole transmission structures. By constantly updating the imagery, the utility can ensure the structure data is current.
- Perform combined patrols
When the Hydro One team goes out on infrared patrols, sometimes they will take photos and videos for the GIS, as well. This eliminates the requirement to repeat their efforts, which saves time and money.
Hydro One's Provincial Lines and Helicopter Operations departments have worked together to meet outage restrictions, which, in turn, improves the reliability of the system. Through annual scheduled patrols, the utility monitors its assets using the helicopters, and in the process, the company has helped to detect outages, improve job planning and increase efficiency.
Companies mentioned:
Eurocopter www.eurocopter.com
Flir InfraRed Systems www.flir.com
Hydro One www.hydroone.com
Polytech Gimbal Systems www.polytech.se
Sikorsky www.sikorsky.com
Sony www.sony.com
Wishbone Safety Inc. www.wishbonesafety.com
