Hydraulic Magnetic

Always carries 100% of rated current with the trip point  un-affected by ambient temperature. (No thermal memory).

Available in the SFM and QF Series MCB's, Miniature RCBO's and RCBO's 

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Overload One

Load current flows through a series connected solenoid coil around a tube which contains an iron core, a spring and dampening fluid. Only Where current above circuit breaker rating occurs does the magnetic flux in the solenoid coil generate sufficient pull on the iron core to move it toward the pole piece.

Overload Two

Whilst this movement is in progress the dampening fluid regulates the speed of
travel of the iron core thereby controlling time delay. Time delay is important in
that if overload is of short duration the core returns to its rest position once the
overload disappears.

Overload Three

If overload persists the core will reach the pole piece after a time delay particular to that current and in so doing the reluctance of the magnetic circuit drops and the armature will be attracted to the pole piece with sufficient force to trip the mechanism. The contacts separate, current ceases to flow and the core returns to its rest position.

Short Circuit One

Load current produced by magnetic force flows through series connected
solenoid coil around a tube which contains an iron core, a spring and dampening fluid.

Short Circuit Two

With high values of overload or short circuit the magnetic flux produced by the
coil is sufficient to attract the armature to the pole piece and trip the breaker without the iron core moving (instantaneous trip region).

Short Circuit Three

After tripping the circuit breaker may be re-closed immediately once fault has been cleared as there will have been no build up of heat and therefore no cooling down period required.

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