From Electrical Installation Guide

The circuit-breaker/disconnector fulfills all of the basic switchgear functions, while, by means of accessories, numerous other possibilities exist

As shown in Figure H20 the circuit-breaker/ disconnector is the only item of switchgear capable of simultaneously satisfying all the basic functions necessary in an electrical installation.

Moreover, it can, by means of auxiliary units, provide a wide range of other functions, for example: indication (on-off - tripped on fault); undervoltage tripping; remote control… etc. These features make a circuit-breaker/ disconnector the basic unit of switchgear for any electrical installation.

Fig. H20 – Functions performed by a circuit-breaker/disconnector
Functions Possible Conditions
Control Functional
Emergency switching (With the possibility of a tripping coil for remote control)
Switching-off for mechanical maintenance
Protection Overload
Insulation fault (With differential-current relay)
Undervoltage (With undervoltage-trip coil)
Remote control Added or incorporated
Indication and measurement (Generally optional with an electronic tripping device)