Wylex Push Button Circuit Breaker
A plug in circuit breaker for Wylex Standard fuseboxes, manufactured by Stotz Kontakt.
Exterior
These circuit breakers are a direct replacement for the rewireable fuses, and are fitted in the same way. The two blades on the rear push into the slots on the fusebox.
The larger button is to set the device, the smaller one to reset or disconnect it. These were common in the 1980s, later versions have a lever on the front.
This example is a 5 amp rating, with a white button.
Cover removed
The cover is secured with two threaded pins, one at each opposite corner. The mechanism is secured to the backplate.
The small red reset button is loose, only held in place by the mechanism behind. In the lid, three metal plates at the top form an arc supression chanber.
Components
Here the metal plates and button are removed. These are held in place by the mechanism only and are easily removed.
The long bar at the top of the mechanism directs any arc from the contact into the arc plates.
Mechanism
The internal mechanism can be seen here, with a view from both sides. Contacts are at the top, trip coil and bimetallic strip at the bottom.
Connections are line in on the lower terminal blade, line out on the top blade.
Trip coil and bimetallic strip
Closer view of the magnetic trip coil and bimetallic thermal trip bar.
Tripping occurs when the flat bar above the coil is pulled down, either by the magnetic coil, bottom strip bending downwards or the red reset button pushing against the angled section at the front.
Internals examined and current applied
The video shows the internals of the circuit breaker and several tests are done by passing a controlled current through the MCB so that ther thermal element causes it to trip.
Additional views of both sides
Views of the left and right sides of the internals.
