MCU Module 8: Electrical Systems

ELECTRICITY

a form of energy generated by friction, induction or chemical change, having magnetic, chemical and radiant effect; the motion of free electrons through a solid conductor.

SOURCES OF ELECTRICITY

1. BATTERY

2. GENERATOR

BATTERY

a combination of two or more electric cells capable of storing and supplying direct current by electro chemical means.

PRIMARY BATTERIES

delivers electricity as soon as its parts are assembled, or put together, provided that it is connected to a circuit

SECONDARY/STORAGE BATTERIES

electricity from some external source must be passed through it before it can deliver an electric current. Uses: to supply emergency lighting for hallways, stairways, exits, police alarms, fire alarm systems, etc.

GENERATORS

a machine that converts mechanical energy into electrical energy.

ALTERNATING CURRENT GENERATORS or ALTERNATORS (AC)

constitutes bulk of electrical energy utilized today, including energy for power and lighting

DIRECT CURRENT GENERATORS (DC)

furnish electrical energy for elevators, escalators, intercom telephone systems, control of signal systems and clod systems

SERVICE

the supplying of utilities required or demanded by the public

SUBSTATION

an auxiliary power station where electrical current is converted or where voltage is stepped up or down

SERVICE DROP

the overhead portion of service conductors extending from a main power line or transformer to a building.

SERVICE LATERAL

THE UNDERGROUND PORTION

SERVICE ENTRANCE CONDUCTOR

the portion of a service conductor extending from a service drop or service lateral to the service equipment of a building

WATT-HOUR METER

a meter for measuring and recording the quantity of electric power consumed with respect to time.

TRANSFORMER VAULT

a fire-rated room housing a transformer and auxiliary equipment for a large building

SWITCHBOARD

one or a group of panels on which are mounted switches, overcurrent devices, metering instruments and buses.

STANDBVY GENERATOR

for providing emergency power during a power outage.

UNINTERRUPTIBLE POWER SUPPLY

an emergency system designed to provide power automatically and instantaneously.

CURRENT

A flow of electric charge through a medium. This charge is typically carried by moving electrons in a conductor such as wire, or by ions in an electrolyte, or by both ions and electrons in a plasma.

AMPERE

Rate or measure of power used or consumed; or rate of flow of electric charge measure in SI units.

VOLT/VOLTAGE

Electrical pressure that causes the electrons to move through a conductor. Unit of electrical potential, named after Alessandro Volta

HERTZ

Frequency of alternating currents, named after HR. Hertz.

OHM

Relationship between current, voltage and resistance, discovered by GEORGE SIMON OHM

WATT

The standard unit (SI) used in measuring the strength of electric current, named after JAMES WATT.

WILLIAM GILBERT

“Father of Electricity”

CIRCUITS

A complete conducting path carrying current from a source of electricity to and through some electrical device or load and back to the source.

CONDUCTORS

materials which allow the free flow of electrons through them

CONDUITS

are circular raceways used to enclose wires and cables and are of metal or plastic (PVC).

RACEWAY

channels or wiring accessories used for holding wires, cables, bus bars.