Articles

Helicopter – Live Power Line Operations

In Uncategorized on May 28, 2010 by hillermuseum

PJ Helicopter working on High Tension Power Lines

The electric transmission line power grid includes thousands of miles of high voltage power lines crisscrossing the country. With few exceptions, factories, offices, and homes receive electric power with outstanding reliability. Flip the wall switch and the light, TV, computer, etc is on. We accept that these appliances require maintenance just as the power plant requires maintenance. However, power lines being passive items and are looked on as not needing attention.  Power lines certainly do need maintenance, just as an appliance and the power plant. An appliance or the generating equipment may be removed from service for maintenance; however, power lines must be in continuous operation. Therefore, maintenance must be performed “energized”, that is, while power is on. Since line potential can be anywhere from 60,000 to 500,000 volts and 50 feet or more above ground, this operation presents a unique challenge. A helicopter is an ideal vehicle for such operations.

P J Helicopters, Inc. and Pacific Gas and Electric Company (PG&E) work together to perform a wide variety of specific power line maintenance. A few of the more interesting activities are:

Bare Hand Live Line Maintenance

To perform bare hand live line maintenance, a PG&E lineman is seated on the work platform attached to the helicopter. The platform can be equipped with a variety of work tools, compressed air, electrical generator, or hydraulic pump. All work is performed in accordance with documented work and safety procedures. The helicopter of choice by PJ Helicopters is a Hughes 500. According to General Manager Jim Uselton, the Hughes 500 is an ideal aircraft for this application. The 500 has five rotor blades, which contribute to the stable hovering needed for the delicate live line work. Ken McClure, PG&E Helicopter Work Procedures Instructor, while sitting on the platform, is then able to perform a range of maintenance functions with the lines energized.

Live line work requires the helicopter to be connected directly to the power line. This is accomplished by hovering within a few feet of the line and attaching a temporary cable from the platform to the line; the platform, helicopter and the personnel are then at the same power line potential. Since there is no connection to “ground” there is no current flow and, hence, no electrical danger.

Inspections

PG&E’s detailed methodical inspection system provides a cost-effective method of data gathering and reporting which ensures total system maintenance. To keep power lines at top efficiency, it is necessary to test for points of resistance, using a device called an ohm’s stick. The testing of sleeves (splices between ends of lines) involves taking a resistance (ohm) reading on each half of the sleeve. Using this measurement, it is possible to determine the amount of deterioration, and whether the sleeve needs attention or replacement. In this procedure, it is not necessary to connect to the line as the measuring device is mounted on a ten-foot fiberglass hot stick. (The photo shows the helicopter in this configuration). By carrying out testing using PJ Helicopter/PG&E’s airborne platform method, productivity of up to twenty joints per hour can be achieved compared with twenty joints per day using ground-based methods, an improvement of up to 800%.

Live Line Insulator Washing and Replacement

Over time, insulators collect dirt and dust which reduce their effectiveness. Helicopter live line insulator washing is an efficient and cost-effective method to reduce contamination. Utilizing the helicopter, a high-pressure stream of water is directed onto and under each insulator for an effective wash. Since pure water is non-conductive, this procedure involves minor risk and power loss. In addition, by utilizing conventional live line hot stick or bare hand procedures, insulator replacement can be carried out significantly faster than by conventional methods.

Cable Stringing

PJ Helicopter uses a specially designed side mounted hook suitable for either distribution or transmission cable stringing applications. This allows for greater visibility and safety for the pilot and ground crew during stringing operations.

Line Patrols

PJ Helicopter’s patrol method provides a cost effective way for PG&E to overview their assets. The line inspector is positioned to provide a 180-degree view up and down the line. These airborne patrols are quicker, more accurate, and more thorough than ground-based methods. The result is a comprehensive report in both electronic and hard copy format, allowing maintenance management to assess all faults identified.

Marker Ball Installation

Marker balls are large, orange spheres placed on power lines to make them visible to aircraft. Installation of marker balls is carried out quickly and efficiently using the helicopter bare hand live line maintenance procedure.

Airborne Personnel Tower Transfers

Helicopter transfers (tower to tower) allow for quick and easy personnel access to the majority of structures within the electrical industry. High levels of productivity are achieved by line personnel with no environmental damage occurring.

Live power line maintenance may appear to be a risky operation; however, extensive safety procedures are built in and followed rigorously. Using a helicopter for these operations is a very efficient and cost-effective method of keeping power flowing to end users

See PJ Helicopters and PG&E demonstrate there amazing skills at the Vertical Challenge Helicopter Air Show at the Museum on June 19, 2010. For more info check out http://www.hiller.org/vertical-challenge.shtml

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