Permanent magnets are at the heart of a new switching device expected to bring big reductions in maintenance costs for factories and electricity substations.
Developer ABB claims its VM1 circuit breaker does not need regular inspection, even when used in arduous environments, bringing cost savings over the product’s lifetime of hundreds or even thousands of pounds.
Unlike other vacuum circuit breakers, the VM1 does not rely on springs and complex latching mechanisms, which can consist of hundreds of parts, to open and close the circuit contactors.
Instead, a magnetic actuator (on the right of the diagram) opens and closes the contactors which are normally closed in operation.
The actuator’s magnetic circuit enables the coils (coloured red) to move the magnet armature (grey) into the open or closed positions relative to fixed permanent magnets (gold).
When the circuit breaker trips, a magnetomotive force of 12,5000 ampere-turns overcomes the permanent magnet field, pulling the armature to the open position. The VM1 caters for 90% of market needs, says ABB.