PPT 2 BU PART 2

PANELBOARDS

popularly known as "panel" or "electrical panel", it is simply the box wherein the protective devises are housed from which the circuits and bus bars terminate.

UNIT SUBSTATIONS

(Transfer Load Centers) an assembly of primary switch-fuse-breaker, step-down transformer, meters, controls, bus bars and secondary switchboard. It is used to supply power from a primary voltage line to any large facility.

REMOTE CONTROL (RC) SWITCHES

A contactor[1], or more specifically, a relay[2], that latches after being operated wireless from a distance.

ROTARY SWITCHES PUSH-BUTTON SWITCHES TOGGLE/TUMBLER SWITCHES

TYPE OF SWITCH - ACCORDING TO OPERATION MECHANISM Wiring switches may also be classified according to the operating mechanism as: (3)

WALL PLATES OR FACEPLATES

These are coverings for switches and wall outlets usually made of metal or of phenolic compound (Bakelite).

TIME CONTROLLED SWITCHES

This device comprises a precision low speed miniature drive motor (timer) to which some type of electric contact-making device is connected.

AUTOMATIC TRANSFER SWITCH (ATS)

This device, an essential part of an emergency or standby service, is basically a double throw switch, generally 3-pole, so arranged that on failure of normal power, emergency service is automatically supplied.

KNIFE SWITCH

a form of air switch in which a hinged copper blade is placed between two contact clips.

DIMMER SWITCHES

a rheostat[1] or similar device for regulating the intensity of an electric light without appreciably affecting spatial distribution. Also called a dimmer. Wiring switches may either be the flush type, surface type or the pendant type.

THROWS

a single throw switch is one which will make a closed circuit only when the switch is thrown in one position. A double throw switch will make a closed circuit when thrown in either of two positions.

FLOAT SWITCH

a switch controlled by a conductor floating in a liquid.

AIR SWITCH

a switch in which the interruption of a circuit occurs in air.

KEY SWITCH

a switch operated only by inserting a key or a card. Also called a card switch.

MERCURY SWITCH

an especially quiet switch that opens and closes an electric circuit by shifting a sealed glass tube of mercury so as to uncover or cover the contacts.

OVER-CURRENT CIRCUIT PROTECTIVE DEVICES

are devices whose sole purpose is to protect insulation, wiring, switches and other apparatus from overheating or burning, due to overloads, to faults or to short circuits, by automatically cutting off the circuit.

SWITCHBOARDS

are free standing assemblies of switches, fuses, and/or circuit breakers whose function normally is to provide switching and feeder protection to a number of circuits connected to a main source.

DISCONNECTING/ ISOLATING SWITCHES

are intended for disconnecting or isolating circuits; used for circuits rated at more than 600 volts.

GENERAL-PURPOSE SWITCHES

are intended for use in general distribution and branch circuits.

GENERAL PURPOSE SWITCHES 3

are single-pole or double-pole switches for the general purpose use of connecting or cutting-off circuits for the control of lamps or other loads from a single point.

ELECTROLIER/ MULTI-CIRCUIT SWITCHES

are used for the control of lights in multi-lamp fixtures so that one lamp or set of lamps may be turned on alone or in combination with other lamps.

FOUR-WAY SWITCHES

are used in conjunction with two 3-wire switches where it is desired to control lamps from three or more desired points.

MOMENTARY CONTRACT SWITCHES

are used where it is desired to connect or cut-off a circuit for only a short duration. The switch is provided with a spring so that it will return to its original position as soon as the handle or button is released.

THREE-WAY SWITCHES

are used where it is desired to control lamps from two different points, as in a stairwell.

WIRING SWITCHES

include all the relatively small switches that are employed in interior wiring installations for the control of branch circuits, individual lamps or appliances.

SERVICE SWITCH

intended to disconnect all the electric service in the building except emergency equipment. This may comprise one to six properly rated switches that are assembled into a switchboard.

FUSE

is a device consisting of an alloy link of wire with a low melting temperature which is inserted in the circuit, in such a way, that all current which passes through the circuit, must also pass through this metal.

GROUND FAULT CIRCUIT INTERRUPTERS (GFCI or GFI)

is an over current protective device that will provide ground fault protection as well as function as an ordinary circuit breaker.

CIRCUIT BREAKERS

is an over-current protective device designed to function as a switch, or it can be manually tripped and thus act as a circuit switch. It breaks a circuit with an automatic tripping device without injury to itself.

POLES

that part of the switch which is used for making or breaking of a connection and which is electrically insulated from other contact making or breaking parts.