Utilities Manual Flashcards
Arc
p. v
An arc is a flow of electric current across a gab between two conductors, terminals, or contacts. Arcs can result in sparks, a loud notice and a momentary or sustained outage as protective equipment operates. An arc can create a large amounts of heat and light.
Breaker
p. v
This term is short for circuit breaker, which refers to a component that detects overload conditions and then disconnects and stops the flow of electrical current to protect and ensure the syatem’s safe operation.
Circuit
p. v
A circuit is a path through which electric current is intended to flow.
Cross arm
p. v
A cross arm is a wooden bar located at the top of a utility pole to which power line are attached. The cross arm keeps the lines seperate by a sufficient distance to prevent arching.
Fault
p. v
In an electrical power system, a fault is any abnormal electrical current. For example, a short circuit in which the current exceeds the normal load is a fault. An open circuit fault occurs when some type of failure interrupts a circuit.
Fuse
p. v
A fuse is a protective device consisting of a conducting material that melts and burns to open the circuit when the current exceeds a specified value. When melted or blown, the fuse interrupts the flow of electricity to prevent equipment damage. The temporary distribution creates an outage until the fuse is replaced. This outcome is deemed far better than the type of extended outage resulting from damaged equipment that need to be replaced, Fuses also limit the number of customers who are affected by the outage.
Intrinsically safe
p. v
In the context of firefighting, something that is intrinsically safe is designed to be incapable of producing heat or spark sufficient to ignite an explosive atmosphere.
Momentary outage
p. v
A momentary outage is an electrical outage lasting 2 min or less.
Pothead
p. v
A pothead is a device that provides a transition between underground cable and overhead lines or conductors.
Primary electric service
p. v
Primary electric service delivers between 2,000 and 50,000 V to a distribution transformer, which, in turn, reduces voltage to secondary levels.
Recloser
p. v
An automatic protection device that sees and interrupts distribution system faults. A recloser automatically tests an electrical line to determinate whether a system fault has been removed. If the fault is no longer present, then the recloser automatically resets itself and restores the electric power.
Riser
p. v
Riser refers to the conductor part of the transition apparatus leading the flow of electricity from underground to overhead. This equipment may or may not include a pothead.
Secondary electric service
p. vi
Caries less than 2,000 V.Most residential and business customers receive electricity from secondary distribution lines.
Sectionalizing
p. vi
Refers to the process of open switches or fuses to divide a power circuit into sections that will isolate the cause of a power outage. This process limits the power outage’s impact to the fewest possible customers by allowing power to move through the system’s undamaged parts.
Stopcock valve
p. vi
A quarter-turn valve used to restrict or isolate the flow of liquid or gas in a pipe.
Substation
p. vi
A location that uses a collection of transformers to alter voltage and circuit breakers to protect circuits.
Sustained outage
p. vi
An electrical outage that lasts more than 2 min.
Switch
p. vi
A device for making, breaking, or changing connections within an electrical circuit.
Switching
p. vi
The process of opening and closing switches to isolate an arefrkm the flow of electricity.
Time-weighted average
p. vi
The average time of exposure to a contaminant or condition (e.g. noise) that workers can experience over a period ( e.g. an 8-hr day or 40-hr week) without incurring adverse effects.
Transformer
p. vi
A device that changes electrical energy from one voltage level to another.
Transmission system
p. vi
Carries electrical power at very high voltages, generally between 60,000 and 500,000 V. The system provides bulk transportation of electricity over long distances, usually from generating sources to substations for bolt age reduction.
Vapor density
p. vi
Refers to the ratio of the weight of a given volume of gas or vapor to the weight of an equal volume of air at the same temperature and pressure. A vapor density of less than 1 indicates the vapor is lighter than air and will rise; vapor density greater than 1 indicates the vapor is heavier than air and will sink.
Vault
p. vi
A space underground for electric cables, transformers and other parts of the underground electric system.
