pg 131-135Key Components of Overhead Distribution Lines

Flashcards covering key overhead distribution line components, including poles, brackets, insulators, conductors, transformers, and protective devices.

What is the most popular material choice for distribution poles, and what is their typical height range?

Wood poles are the most popular choice, with the majority of distribution poles falling in the 35- to 55-foot height range.

Why are fiberglass and steel poles used for distribution applications despite higher initial costs?

They are used in various applications where their long-term benefits outweigh their higher initial cost.

What materials are used to make supporting brackets for mounting equipment like transformers, cutouts, and lightning arresters?

Brackets are made from steel, fiberglass, and aluminum.

How do post insulators differ from pin insulators in terms of contact area and conductor size compatibility?

Post insulators offer more contact area at the point of attachment than pin insulators and are used with larger conductors.

Where on distribution structures are polymer insulators most commonly found?

Polymer insulators are most commonly found at dead-end structures.

What factors determine the selection of the size and type of conductor for distribution lines?

Selection is based upon how much power the line needs to carry, the length of the line, the span lengths, weather environment, line losses, and the cost of the conductor.

How does conductor size vary between main lines and tap lines in a distribution system?

Large conductors are found on main lines starting at the substation, while smaller conductors are found further down the line and almost always on tap lines serving a limited number of customers.

What is the key element used to reduce voltage on distribution lines to a level usable by customers?

The pole-mounted distribution transformer.

Why is the single-phase transformer unit the most popular transformer choice in distribution systems?

It is versatile because it can be used to provide single-phase service individually or three-phase service when two or three units are connected in a bank.

What primary devices make up the protective equipment on distribution systems?

Protective equipment consists mainly of fused cutout switches, reclosers, sectionalizers, and lightning arresters.

What is the main design goal and purpose of coordinated protective equipment on distribution circuits?

Protective equipment is designed and coordinated to distinguish temporary faults from permanent faults, minimize outage time to customers, and limit the number of customers affected.