White Paper – Circuit-Breaker Terminals and Connections

pends not only on the quality of the design and components

but also on the methods of installation.

Among the components of an electrical plant, the cables and

the bars play an important role. Besides taking into consid-

eration the project (choice of the conductor type, cable sizing

and method of installation, etc.), an aspect requiring particular

attention is the connection method of the protective device to

the terminal.

is aimed at giving useful hints for the connection of the ca-

bles/bars to the circuit-breaker terminals. This document is

accompanied by numerous tables which privilege the informa-

tion about the connection cable/bar-terminal, trying to limit to

the necessary the descriptions of the different components

(cables, bars, cable terminals, etc.) already documented by

the manufacturing companies.

nect properly the cable or the bar to the circuit-breaker

taking some particular measures and following some useful

advices. Thus, some inconveniences can be avoided, e.g. the

problems deriving from local heating near the circuit-breaker

terminals, blackening marks on the insulating material and on

the conductor, premature aging of the part of cable near to

the circuit-breaker, etc. …, aspects which cannot be neglect-

ed since the cable may be the cause of flame ignition with

dangerous consequences from the point of view of the safety

of people and goods.

− components used for wiring: this part gives a description of

the components mentioned in this paper;

− ABB SACE offer: this part offers a panorama of the con-

nection terminals of ABB SACE circuit-breakers:

circuit-breakers to the electrical plant. The descriptions are

limited to the necessary information since these products are

not the main subject of this paper.

tion the service and short-circuit temperature changes. In

the low voltage field the cables which are used more can

be divided into two main classes:

– insulating cables with elastomeric material (ethylene pro-

– insulating cables with thermoplastic material (polyvinyl

bly of conductors aimed at allowing the current flow.

− sheath: the main function of the sheath is protecting the

called cores: therefore a cable can be single-core, that is

formed by a single core, or it can be formed by more cores

(two-core, three-core and multi-core cables) enclosed in a

protective sheath.

Generally a cable used for LV electrical energy distribution

is formed by the following elements (not always in a cable

used for electrical wiring all these components are necessarily

present):

− conductor: metal part, usually in copper (Cu) or aluminium

(Al), intended to carry the current;

− insulating material: the main function of the insulation is

insulating the conductors one from the other and from the

or of possible chemical agents; besides, in multi-core ca-

bles, the sheath encloses the whole of the different cores;

− shield: it is constituted of a thin copper strip which has the

task of neutralizing the electric fields and the consequent

disturbances;

− armor: the main function of the armor (if present) is pro-

tecting the cable against external agents (chemical agents,

humidity, mechanical stresses, etc.); usually the armor is

constituted by wires or steel or copper strips;

− filler: it has the function of filling the spaces among the

cores of multi-core cables giving it a round shape; this

material is usually constituted of textile fiber.

5 IMQ identification wire