Circuit-breaker

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

As shown in Figure H23 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.

Functions		Possible Conditions
Isolation
Control	Functional
	Emergency switching	(With the possibility of a tripping coil for remote control)
	Switching-off for mechanical maintenance
Protection	Overload
	Short-circuit
	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)

Fig. H23: Functions performed by a circuit-breaker/disconnector

Contents

Standards and description of circuit-breakers Fundamental characteristics of a circuit-breaker Other characteristics of a circuit-breaker Selection of a circuit-breaker Coordination between circuit-breakers Discrimination MV/LV in a consumer’s substation Circuit-breakers suitable for IT systems Ultra-rapid circuit breaker

ru:Автоматический выключатель zh:断路器