Abstract: A residual current circuit breaker 1 has a partition wall 3 which separates an over-current protection device 4 from a residual current detection circuit 5. A plunger rod 24 extends through a bore 23 in the armature 21 of a coil 20 and is moved independently through the coil 20 to trip the breaker if a residual current is detected by the circuit 5. The plunger rod 24 is moved by a drive rod 31, the operation of which is controlled by a permanent magnet which retains the drive rod 31 retracted and an electromagnet which allows the drive rod 31 to drive forwardly under the action of a spring 32 in the event of a residual current being detected. The plunger rod 30 is reset by a reset lever 40 which is moved when an operating handle 18 of the breaker moves from a non-tripped to a tripped position on tripping of the breaker.

Abstract: A circuit interrupter is disclosed which provides for tripping of a line lead on occurrence of a loss of neutral or an earth leakage fault without the need for an earth connection. The circuit interrupter includes a circuit breaker which is activated by discharge of a capacitor in a closed loop, the capacitor being connected across the output of a D.C. power supply. A loss of neutral fault is detected as the potential of a neutral lead rises through a pull-up resistor and tripping will occur before the neutral rises to a potential at which the power supply becomes inoperative.

Abstract: A loss of neutral detector is disclosed. The detector includes a closed loop circuit which has a charge storage device, an output device and a switch in a normally-open position. The switch is controlled by a switch control circuit operatively connected to a loss of neutral detection circuit. The loss of neutral detection circuit detects an electro-magnetic field generated around the neutral lead on increase of the neutral potential via a pull-up resistor on loss of neutral. On detection of loss of neutral, the switch is closed so that the charge storage device energizes the closed loop circuit to activate the output device.

Abstract: A residual current circuit breaker 1 has a partition wall 3 which separates an over-current protection device 4 from a residual current detection circuit 5. A plunger rod 24 extends through a bore 23 in the armature 21 of a coil 20 and is moved independently through the coil 20 to trip the breaker if a residual current is detected by the circuit 5. The plunger rod 24 is moved by a drive rod 31, the operation of which is controlled by a permanent magnet which retains the drive rod 31 retracted and an electromagnet which allows the drive rod 31 to drive forwardly under the action of a spring 32 in the event of a residual current being detected. The plunger rod 30 is reset by a reset lever 40 which is moved when an operating handle 18 of the breaker moves from a non-tripped to a tripped position upon tripping of the breaker.

Abstract: A ground fault circuit interrupter which continues to provide ground fault protection in the event of loss of neutral includes a blocking means formed by a pair of back-to-back Zener diodes which complete an energizing path for a circuit breaker on loss of neutral. The circuit interrupter also includes a standby rectifier circuit formed by a pair of diodes which complete a full wave rectifier having line and earth inputs in the event of loss of neutral.

Abstract: A loss of neutral or ground protection circuit is disclosed which uses a simple capacitive circuit which discharges through the neutral or ground leads in normal conditions, and in the event of loss of neutral or ground charges sufficiently to trip a circuit breaker. The protection circuit may include other circuits such as ground fault detection circuits and may be in a one or three phase system. By virtue of the fact that a capacitive circuit is used to trip the circuit breaker, an inherent time delay is involved and thus the circuit breaker will not be tripped as a result of a momentary loss of neutral or ground. This is particularly important where continuity of operation of a load is important.