Circuit Breaker Demonstration

Description

This unit shows all the working parts of a modern circuit-breaker type fuse as used in domestic
consumer units. The apparatus is contained within a robust plastic tray with protective acrylic
cover and includes resistive loads to simulate external wiring circuits. Applications of the thermal
response of bimetal strips and also electromagnetism (movement from a solenoid) are clearly
demonstrated as well as the performance of the circuit breaker itself. When a 12V d.c. supply is
connected (not supplied) the LED lights to show that current is flowing in the external circuit and the
bi-metal strip can be seen to bend as its heater coil raises the temperature. After a few minutes the
bending is sufficient to trip the mechanism and the current path is broken. At any current selection
a short circuit situation can be initiated by pressing the red button and this produces an immediate
response from the solenoid to disconnect the supply. This unit should prove invaluable to those
wishing to show how this type of device operates as well as for teachers requiring an additional
aid to show applications of bi-metal strips and electromagnetic devices. SP4-0941