Electrical Switch Definitions

SWITCH TYPES

AIR SWITCH

An air switch is a switch in which the interruption of the circuit occurs in air. Air is used as the insulation medium between the open contacts (air break switch).

CENTER BREAK SWITCH

A center break switch is a switch with two rotating insulators, located at each end of the base. Rotation of the insulators cause the blade and contact to engage at a point approximately midway between the insulators.

DISCONNECTING SWITCH

A disconnecting switch is an air switch used for changing connections in a circuit or system, or for isolating purposes. It is intended to be operated only after the circuit has been opened by some other means. It has no interrupting rating.

DOUBLE BREAK SWITCH

A double break switch is a switch which opens the connected circuit at two points.

DOUBLE THROW SWITCH

A double throw switch is a switch by means of which a change in circuit connections can be obtained by closing the switch blade into either of two sets of contacts.

FULL LOAD INTERRUPTERS SWITCH

Is an interrupter switch having a current interrupting rating, under specific circuit conditions, equal to the continuous current rating of the switch at rated voltage.

FUSED DISCONNECTING SWITCH

A fused disconnecting switch is a disconnecting switch in which a fuse unit forms a part of the blade.

GROUNDING SWITCH (Ground Switch)

A grounding switch is a form of an air switch by means of which a circuit or a piece of apparatus may be connected to ground.

HIGH SPEED GROUNDING SWITCH

Is a grounding switch which incorporates a stored energy mechanism capable of providing a high contact closing speed, at its rated current, independent of the operator. The switch is either opened manually or by a power operator.

HORN GAP SWITCH

A horn gap is a form of an air switch which is provided with arcing horns.

INTERRUPTER SWITCH

An interrupter switch is a combination of an air disconnect switch and a circuit interrupter, which has a current interrupting rating, under specific circuit conditions, equal to or less than the continuous rating of the switch at rated voltage.

ISOLATING SWITCH

An isolating switch is a switch intended for isolating an electric circuit from the source of power. It has no interrupting rating and is intended to be operated only after the circuit has been opened by some other means.

LIMITED CURRENT INTERRUPTER SWITCH

Is an interrupter switch limited to certain types of application, where the types and magnitude of certain interruptions, at rated voltage, is less than the continuous current rating of the switch such as small load currents, magnetizing currents, or capacitor currents.

MOUNTING POSITION OF AN AIR SWITCH

The mounting position of an air switch is determined by and corresponds to the position of the base of the switch. The usual positions are:

1. Horizontal upright
2. Horizontal underhung
3. Vertical
4. Angular

OIL SWITCH

An oil switch is a switch in which the interruption of the circuit occurs in oil. Oil is used as the insulation medium between the open contacts.

ROTATING INSULATOR SWITCH

A rotating insulator switch is a switch in which the opening and closing travel of the blade is accomplished by the rotation of one or more of the insulators supporting the conducting parts of the switch.

SECTIONALIZING SWITCH

A sectionalizing switch is a switch used for connecting or disconnecting adjacent sections of conductors or feeders.

SELECTOR SWITCH

A selector switch is a form of air switch arranged so that a conductor may be connected to any one of several other conductors.

SIDE BREAK SWITCH

A side break switch is a switch in which the travel of the blade is in a plane parallel to the base of the switch.

SINGLE BREAK SWITCH

A single break switch is a switch which opens the connected circuit at one point only.

SINGLE THROW SWITCH

A single throw switch is a switch by means of which the circuit can be opened or closed by moving the switch blade into or out of one set of contacts only.

SWITCHES

A switch is a device for making, breaking, or changing the connections in an electric circuit.

TILTING INSULATOR SWITCH

A tilting insulator switch is a switch in which the opening and closing travel of the blade is accomplished by a tilting movement of one or more of the insulators supporting the conducting part of the switch.

VERTICAL BREAK SWITCH

A vertical break switch is a switch in which the travel of the blade is in a plane perpendicular to the plane of the base mounting.

OPERATION

DIRECT OPERATION

Direct operation of a mechanically operated switch is the operation by means of a mechanism connected directly to the main operating shaft, or an extension of it.

GROUP OPERATION

Group operation of a multipole switch is the operation of all poles by means of one operating mechanism.

HOOK OPERATION

Hook operation of a switch is the operation manually by means of a switch hook.

INDIRECT OPERATION

Indirect operation of a switch is the operation by means of an operating mechanism connected to the main operating shaft, or an extension of it, through offset linkage and bearing.

MANUAL OPERATION

Manual operation of a switch is the operation by hand without using any other source of power.

MECHANICAL OPERATION

Mechanical operation of a switch is the operation by means of an operating mechanism connected to the switch by mechanical linkage. The operating mechanism may either be hydraulic, pneumatic, or a combination of both. The mechanical operation of a switch may be actuated either manually, or electrically, or by other suitable means.

OPERATING MECHANISM

The operating mechanism of a switch is a power operated or manual mechanism by which the contacts of all poles are actuated.

OPERATION

The operation of an air switch is the method provided to perform its normal function, that of opening or closing.

POWER OPERATION

Power operation of a switch is the operation by power, such as motor operator, spring operator, pneumatic operator, or hydraulic operator.

REMOTE CONTROLLED OPERATION

Remote controlled operation of a switch is the operation by means of an operating mechanism controlled from a distant point either manually and/or electrically or by other means.

CONSTRUCTION & PARTS

ARCING CONTACTS (ARCING HORNS) (PARKING HORNS)

Arcing contacts are the contacts on which the arc is drawn after the main contacts of a switch have parted.

BASE

A base of a switch is the main member to which the conducting parts or insulator unit are attached. It may also have parts of the operating or control mechanism attached.

BELL CRANK or OUTBOARD BEARING

A bell crank is a lever with two or more arms placed at an angle diverging from a given pivot point, by means of which the direction of motion of a mechanism is changed.

BELL CRANK HANGER

A bell crank hanger is a support for a bell crank.

BLADE

A switch blade is the moving contact member which moves to engage or disengage the conductors.

BLADE GUIDE

A blade guide of a switch is an attachment to secure proper alignment of blade and contact when closing the switch.

BLADE LATCH

A blade latch is a latch used on a switch to hold the switch blade in the closed position.

CLEVIS

A clevis is a fitting having a U-shaped end and arranged for attaching to the end of a pipe or rod.

CONTACT

The contact is a conducting part designed to be united by pressure to another conducting part for the purpose of carrying current.

CONTACT SURFACES

Contact surfaces are the surfaces of contacts which meet and through which the current is transferred when the contacts are closed.

CURRENT CARRYING PARTS

Current carrying part is a conducting part intended to be connected in an electric circuit to a source of voltage.

EXTENDED OUTRIGGER CLAMP

An extended outrigger clamp is an attachment fastened to the terminal pad of a switch to which the conductor is clamped to relieve mechanical strain on the terminal.

INTERPHASE CONNECTING RODS

Interphase connecting rods are the rods connecting the several poles of a switch together, and to the operating rods.

LIVE PARTS

Live parts are those parts which are electrically connected to points of potential different from that of the ground.

MOVING CONTACT MEMBER

A moving contact member of a switch is a conducting part which bears a contact surface that moves to and from the stationary contact.

OPERATING RODS

Operating rods or pipes connecting the interphase connecting rods or pipes and the operating mechanism of an air switch.

OUTRIGGER

An outrigger is an attachment which is fastened to or adjacent to the terminal pad of a switch and to which the conductor is clamped to relieve mechanical strain on the terminal and/or to maintain electrical clearance between the conductor and the grounded parts.

PIPE END (ROD END)

A pipe end is a fitting arranged to connect the end of a pipe or rod to a lever, bell crank, or other part.

POLE

A pole of a switch consists of the parts necessary to control one conductor of a circuit. A switch may be single pole or multipole, depending upon the number of single poles that are operated simultaneously.

SLEET HOOD

A sleet hood of a switch is a cover for the contacts to prevent the accumulation of sleet from interfering with the successful operations of the switch.

STATIONARY CONTACT MEMBER

A stationary contact member of a switch is a conducting part which bears a contact surface that remains stationary.

SWITCH MECHANISM

A switch mechanism is an assembly of levers and other parts which actuate the moving contacts of the switch.

TERMINAL PAD

A terminal pad of a switch is the extension provided on the switch to which the terminal connection is fastened.

WIRE GUIDE

A wire guide is an attachment to maintain a conductor in a definite position with relation to the switch.

MISCELLANEOUS TERMS

CLEARANCE

Clearance is the minimum distance between two conductors, between conductors and supports or other objects, or between conductors and ground.

CORONA

Corona is a luminous discharge due to ionization of the air surrounding a conductor around which a voltage gradient exists exceeding a certain critical value.

DRIP-PROOF

Drip-proof means go constructed or protected that its successful operation is not interfered with when subjected to falling moisture or dirt.

DRIP-TIGHT

Drip-tight means so constructed or protected as to exclude falling moisture or dirt.

GROUND

A ground is a conducting connection, between an electric circuit or equipment and earth, or to some conducting body which serves in place of' the earth.

GROUNDED

Grounded means connected to earth or to some conducting body which serves in place of the earth.

GROUNDED PARTS

Grounded parts are those parts which are so connected that, when the installation is complete, they are substantially of the same potential as the earth.

INSULATOR UNIT (INSULATOR STACK)

The insulator unit of an air switch is the insulating part or assemblies that isolates the current carrying parts from ground.

INTERLOCK

An interlock is a device actuated by the operation of some other device with which it is directly associated, to govern succeeding operation of the same or allied devices.

MINIMUM CLEARANCE BETWEEN POLES

The minimum clearance between poles is the shortest distance between any live parts of adjacent poles.

MINIMUM CLEARANCE TO GROUND

The minimum clearance to ground is the shortest distance between any live part and adjacent grounded parts.

PHASE SPACING

The phase spacing of air switches is the distance between centers of the live parts or conductors of one pole and the current carrying parts of an adjacent pole.

QUICK BREAK

A switch is quick break when it has a high contact opening speed independent of the operator.

QUICK MAKE

A switch is quick make when it has a high contact closing speed independent of the operator.

SPARK GAP

A spark gap is an arrangement of two electrodes between which a disruptive discharge or electricity may take place, and such that the insulation is self restoring after the passage of a discharge.

SWITCH HOOK

A switch hook is a hook provided with an insulating handle for opening and closing hook operated switches.

VOLTAGE TO GROUND

The voltage to ground is the voltage between any live conductor or a circuit and the earth.

WATERTIGHT

Watertight means provided with an enclosing case which will exclude water applied in the form of a hose stream for a specific time.

WEATHERPROOF - (OUTDOOR)

Weatherproof means so constructed or protected that exposure to the weather will not interfere with its successful operation.