High Speed DC Circuit Breaker - G E Power Controls

3.2.3 Mechanism
• The Gerapid is equipped with a modular designed
mechanism, wear-resistant and nearly maintenancefree.
This mechanism ensures an extended electrical
and mechanical endurance of the breaker as well as a
high amount of safety for all operation conditions.
• This mechanism is mechanically latched in CLOSE position.
The principle of a mechanical latch mechanism offers
the big advantage, contrary to often used holding
magnet system. No auxiliary control power source is required
to keep close.
• The mechanism is provided with two latches [Fig. 6]. One
of the latches, “slow latch”, is used for opening under
normal conditions, like actuation of shunt trip or zerovoltage
release. The other one, “quick latch”, de-clutches
the main contact arm from the mechanism and open
contacts with an extremely short delay. This is used in
case of short-circuit or overloads. All safety releases operate
onto this latch.
3.2.4 Over-Current Tripping device (code nr: 7)
• The OCT device is a release magnet with twin magnet
circuits, optimizing the twin magnetic field principle [Fig.
7]. This technology ensures an equally fast tripping in
both current directions.
• The magnetic system does not require an auxiliary control
voltage to operate. It uses magnetic energy from the
main circuit.
• The system consists of the holding circuit [6], the movable
armature [3] and the tripping circuit [7]. The holding
and the tripping magnetic circuits are both excited by
main current [1]. Until the static overload release’s response
threshold has been reached, the armature [3] is
held in position by the holding flux (ΦH) [2] and the
counter spring’s force [4]. Once the main current exceeds
the set static response threshold, the attraction
flux (ΦA) [2] takes over and pulls rapidly down the flexible
armature [3]. During this operation, the armature hit
the seesaw, which releases the quick latch in the
mechanism. The latch and contacts are opened immediately.
• The response threshold can be easily adjusted by turning
the adjustment nut with a SW6 hexagon wrench as
described in point 2.3.2.
• In combination with the transparent side protection
covers (code nr: 15), a fixed mounted insulated knob is
available to enable OCT adjusting [Fig. 16].
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Fig. 6 Latching and tripping system
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1. Current flow direction.
2. Magnetic core with two fluxes (holding flux ΦH and attracting flux ΦA).
3. Movable anchor.
4. Pressure spring for movable anchor.
5. Short circuit rings.
6. Holding magnetic circuit.
7. Tripping magnetic circuit.
Fig. 7 OCT device
S47183-e 01/2008 Design and specifications are subject to change without notice 7