There are three distribution arrester types commonly used to protect overhead distribution equipment from the damaging effects of overvoltage. IEEE C62.11 defines Normal Duty (ND) and Heavy Duty (HD) classes by their ability to withstand certain current impulse levels. The third, Heavy Duty Riser is a type, or variation, of the HD classification and utilizes a larger diameter Metal Oxide Varistor (MOV) disc.
- Once all safety concerns have been addressed, attach the Kelly bar adapter and installing tool assembly to the Kelly bar on the installing truck.
- Insert the upper end of the anchors’ lead section into the installing tool. Position the anchor at the desired guy location and at a near vertical position; screw the first helix into the ground.
- When the first helix is buried, begin to make the angular adjustment for the desired guying angle.
- Remember, final angular adjustments should be made before the second helix penetrates the ground.
- When the installing tool becomes 12”-18” from the ground, disconnect it from the section in the ground and reconnect it to the next extension.
As with most mechanical devices, CHANCE® anchor-installing tools periodically require maintenance checks to ensure peak performance.
In the case of the shear-pin torque limiter, (see drawing below to the right) you should be able to rotate the tool shear halves independently from one another using a smooth-turning action. If rotation cannot be done by hand or if movement is challenging, disassemble the torque indicator to check the thrust bearing, washers and/or pin for wear.
When comparing different arrester designs, it is important to understand how the arrester was built to correctly evaluate the amount of protection it will provide. The IEEE C62.11 standard covers two types of Metal Oxide Varistor (MOV) distribution arresters that are available today, internally gapped and gapless. These arresters might look identical from the outside, but the different internal module design affects how the arrester protects voltage sensitive equipment.
- Choose anchor site carefully. Rock anchors will only perform effectively in solid competent rock (Class 0 Soil).
- Drill the hole into the competent rock a minimum depth of 12 inches along the drill steel. Be sure to drill so that the anchor rod will be in line with the guy.
- Holes should be drilled so the diameter is optimally an 1/8th inch larger than the diameter of the unexpanded anchor. For example, the hole drilled for a R315 is 1-7/8 inch diameter. However, drill bits are usually available in 1/4 inch increments. In practice, a 2 inch diameter hole is drilled for the R3_ series anchors and a 2-1/2 inch dia. hole is drilled for the R1_series anchors. Be sure to thoroughly clean the drilled hole of rock dust and debris.
The safety procedures described below are the basic steps and necessary equipment linemen will employ when replacing an insulator from an aerial lift truck on a tangent structure with rubber gloves.
- A hold-off is recommended on the line to ensure the line is locked out after an automatic protection operation.
- A tailboard briefing is held with all workers before the work starts to ensure all procedures are understood. Proper safety precautions should be observed. Each person should know specifically what they are required to do. All workers should
Topics: Lineman Grade Tools
When considering an underground enclosure specifics matters. It is important to take load ratings into consideration. For confidence in selecting the right load ratings it is recommended to choose out of the two verified ratings, the ANSI/SCTE77 or the AASHTO H20. When determining the best load rating consider the enclosures intended use.
The ANSI rating is best for non-deliberate traffic areas. These enclosures are placed where direct wheel impact is not likely or anywhere that traffic is not intended. The area may include grassy areas, sidewalks, highway berms, light pole bases, highway median strips and parking lots. These enclosures are designed to handle only occasional, non-intentional traffic.
Four years, several prototypes and thousands of installations later, Hubbell has satisfied Alliant Energy’s need for a stronger neutral clevis.
Alliant Energy identified the need for a better neutral clevis more than a decade ago. Their distribution system has an under-hung neutral and some neutral conductors were attached to poles with vertically mounted clevises. In other words, the neutral was held to the side of the vertically-oriented, spool insulator by a steel tie wire.
Topics: Pole Line Hardware
"Proper alignment" and "down pressure" are simple phrases to summarize proper anchor installation technique. The Power Installed Screw Anchor (PISA®) wrench transmits torque from the digger’s Kelly bar to the anchor hub. Note: The anchor rod only has to be of sufficient diameter to support the guy load.
Underground enclosures, commonly call handholes, pits, or vaults, come in a variety of shapes and sizes and house critical electrical, telecommunications, gas and water service connections. While each underground enclosure application may be different, there are a few installation fundamentals that should be followed to minimize field damage and help insure many years of use.