International electrotechnical vocabulary, switchboards and apparatus for connection and regulation, part 1
Understanding electricity requires knowledge of these basic electrical terms.
Switchboards and apparatus for connection and regulation.
Switchgear. A general term applicable to an assembly of main and auxiliary switching apparatus for operation, regulation, protection or other control of electrical installations.
Switching equipment (of a machine or apparatus). Switchgear associated with the control of a particular circuit, machine or apparatus.
Interlocking device. A mechanical, electrical or other device which makes the operation of an apparatus dependent on the state or the position of one or more devices other than the controlled apparatus.
Sequence of operation. The predetermined order in which a number of operations takes place.
Main circuit of a switching device (contactor, selector, switch, etc.). All the conducting parts of a device included in the circuit which the device is designed to make, break or modify.
Auxiliary circuit of a switching device (contactor, selector, switch, etc.). All the conducting parts of a device other than those that are included in the circuit which the device is designed to make, break or modify.
Pole of a switching device. All the electrical parts associated with a particular line or phase of the device.
Contact (abstract sense). A condition brought about when two conductors touch.
Types of construction and physical protection
Oil-immersed apparatus. Apparatus in which the main parts, or some of these parts, are immersed in oil.
Single-tank switch. Single-tank circuit-breaker. A multipole switch or circuit-breaker with a single oil-filled tank containing the breaking elements of all the poles. A switch or circuit-breaker in which each pole may be operated independently of the others.
Indoor apparatus. Apparatus designed for use only inside buildings.
Outdoor apparatus. Apparatus designed for use out of doors.
Open type apparatus. Apparatus in which live parts can be touched.
Screened apparatus. Partially enclosed apparatus. Apparatus in which live parts are protected from accidental contact by persons.
Totally enclosed apparatus. Apparatus completely enclosed in such a way as to make it impossible for foreign bodies to make accidental or intentional contact with a live part so long as the enclosure is in position. Apparatus protected or enclosed by a metal casing, which is usually earthed grounded.
Metal-clad apparatus. Apparatus in which the components are covered by an earthed grounded) metal casing fitting over the en closed conductors and insulation and are capable of assembly in relation to each other to form a self-contained structure.
Flameproof apparatus. Apparatus designed to work in an inflammable atmosphere and so con structed that it cannot ignite the surrounding atmosphere during operation under given conditions.
Terminal. A conducting element оf an apparatus designed for con necting it to external conductors.
Earth terminal. Ground terminal. A terminal intended to ensure, by means of a special connection, the earthing grounding) of part of an apparatus.
Contact member (abbreviated: contact). A conductor designed to cooperate with another to establish contact.
Contacts (concrete sense). Two or more cooperating contact members relatively movable to open or close a circuit.
Main contacts. Contacts introduced into the main circuit of an apparatus. For contact members consisting of more than one element, main contacts are the co-operat ing elements that normally carry the greatest part of the current.
Arcing contact. The contact on which the arc is drawn after the main (and intermediate, when used) contacts have parted.
Auxiliary contact. A contact introduced into an auxiliary circuit of the apparatus.
Earthing contact. Grounding contact. A contact used to earth (ground) parts of a device.
Normally open auxiliary contacts. NormaIIy open interlock. Auxiliary contacts of a switch or circuit-breaker which are open when the switch or circuit-breaker is open.
Normally closed auxiliary contacts. Normally close interlock. Auxiliary contacts of a switch or circuit-breaker, which are closed when the switch or circuit-breaker is open.
Rest contact. Normally closed interlock. Auxiliary contact of an apparatus having only one rest position. This contact is closed when the apparatus is deenergized.
Operating contact. NormaIIy open interlock. Auxiliary contact of an apparatus having only one rest position. This contact is open when the apparatus is deenergized.
Butt contacts. A contact arrangement in which relative movement of the cooperating members is substantially in a direction perpendicular to the surface of contact.
Sliding contacts. A contact arrangement in which relative movement of the cooperating members is substantially in a direction parallel to the surface of contact.
Rolling contacts. A contact arrangement in which one cooperating member rolls on the other.
Fixed contact. The fixed part, rigidly fixed, of a contact member.
Plug. A detachable element connected to one or more conductors which is designed to be inserted in a socket of appropriate shape in order to establish one or more connections.
Pridging plug. Plug. A detachable element, usually shaped like a truncated cone and not connected to any conductor, designed to establish contact when inserted between two contacts.
Pin. A conducting member, rigid or resilient, intended to be inserted in a socketcontact of suitable form so as to make electrical contact.
Socket-contact. A conducting member, rigid or resilient, intended to receive a suitable pin so as to make electrical contact.
Movable element (of an apparatus). The movable part of an apparatus which carries the movable contact member and the movement of which performs the operation (making and breaking).
Latch (of an apparatus). A device which holds the movable element of an apparatus in a set position against the action of springs or gravity.
Tripping device. A device which, by acting mechanically upon a retaining mechanism, permits stored energy to open a circuit-breaker.
Re-setting device. A device by which a retaining mechanism is returned to its set position from which the apparatus can again be tripped.
Arc-control device. A chamber partially or completely surrounding the contacts of a switch or circuit-breaker, designed to confine the arc and to assist in extinguishing it.
Arc-chute. A chamber into which the drc is transferred to assist in extinguishing it.
Blow-out coil. A coil designed to produce a magnetic field arranged to deflect an arc, e. g. into an arc chute.
Push-button. Part of an electrical device, consisting of a button which must be pressed to effect an operation.
Cable entry. A device to permit the passage of a cable through a partition or the casing of an apparatus.
Bush. A device permitting the passage of a conductor through a partition or the casing of an apparatus.
Compression gland. A cable entry providing a seal by the compression of deformable material.
Bushing. An insulating structure including a through conductor or providing a passageway for such a conductor, with provision for mounting on a barrier.
Base of a device. The fixed part of a device on which its components are mounted.
Locating device. A device intended to ensure that the movable element of an apparatus (a con troller, for instance) is brought to rest in one of a number of definite positions.
Manual control. Control of an operation by human intervention.
Automatic control. Control of an operation, without human intervention, in response to the occurrence of a predetermined condition.
Local control. Control of an operation by a device located on or adjacent to the controlled apparatus.
Remote control. Control of an operation from a distance: this involves a link, usually electrical, between the control device and the apparatus to be operated.
Hand operation. Actuation of an apparatus by hand without auxiliary power.
Power operation. Actuation of an apparatus by electrical, spring, pneumatic or hydraulic power.
Inching. Jogging. Energizing a motor or solenoid repeatedly for short periods to obtain small movements of the driven mechanism.
Independent manual operation. An operation by hand in which energy stored during the initial part of the operation is later used to complete the closing operation independently of the operator.
Automatically operated apparatus. An apparatus containing elements which are sensitive to variations of a physical quantity, which variations actuate the apparatus under predetermined conditions.
Thermally-operated device. A device which is actuated by the thermal effect of a current passing through it.
Trip-free (circuit-breaker). A circuit-breaker provided with a device which overrides any attempt to hold it closed when predetermined conditions requiring it to open have been established.
Lock-out device (circuit-breaker with...). A circuit-breaker provided with a device which overrides any attempt to close the circuit-breaker when predetermined conditions requiring it to open have been established.
Automatic reclosing circuit-breaker. A circuit-breaker provided with rpeans for automatically reclosing it after it has opened under fault conditions.
Instantaneously-operating apparatus. An apparatus in which operation takes place when a predetermined condition (e. g. value of current or voltage) is reached.
Time-lag apparatus. An apparatus in which operation takes place some time after the instant at which the conditions which cause it to operate are established.
Definite time-lag (circuit-breaker, release or relay). A time-lag circuit-breaker, release or relay in which the time-lag is independent of the magnitude of the quantity causing operation.
Inverse time-lag (circuit-breaker, release or relay). A time-lag circuit-breaker, release or relay in which the time-lag varies inversely with the magnitude of the quantity causing operation.
Overcurrent [overvoltage] release. A device which operates automatically when the current passing through it or the voltage applied to it exceeds a predetermined value.
Under-current [under-voltage] release. A device which operates automatically when the current passing through it or the voltage applied to it falls below a predetermined value.
Reverse current release (direct current). A device which operates automatically when the direct current through it has reversed its normal direction.