ABB V-Contact VSC Medium Voltage Vacuum Contactors "MAC" magnetic drive

ABB has implemented this technology in the field of contactors on

the basis of experience gained in the field of circuit-breakers with

magnetic drive.

The magnetic drive adapts perfectly to this type of apparatus thanks

to its precise and linear travel.

The drive, which is of bistable type, is fitted with an opening and a closing coil.

The two coils - individually energised - allow the drive mobile armature

to be moved from one of the two stable positions to the other.

The drive shaft is solid with the mobile armature and held in position

in a field generated by two permanent magnets (fig. A).

Energising the coil opposite to the magnetic latching position (fig.

A) of the core, the magnetic field is generated (fig. B), which attracts

and moves the mobile armature into the opposite position (fig. C).

Every opening and closing operation creates a magnetic field

concordant with the one generated by the permanent magnets, with

the advantage of keeping the intensity of the field itself constant

during service, regardless of the number of operations carried out.

The energy needed for operation is not supplied directly by the

auxiliary power supply, but is always "stored" in the capacitor which

acts as an energy accumulator, and therefore operation always takes

place with constant speeds and times, independently of the divergence

of the power supply voltage from the rated value.

The auxiliary power supply has the only aim of keeping the capacitor  charged.

Consumption is therefore minimal. The power required is less than

5 W. In order to re-instate the rated power value in the capacitor

after an operation, there is an inrush of 15 W for a duration of a few

tens of milliseconds. For the reasons indicated above, both for the

DCO and for the SCO version it is necessary to supply the auxiliary

circuits which recharge the capacitor with a continuous auxiliary

power supply of 5W (this value can reach 15W for a few milliseconds

immediately following each operation). Careful selection of the

components and a precise design make the electronic multi-voltage

feeder extremely reliable, unaffected by electromagnetic interference

generated by the surrounding environment and free of any emissions

which may affect other apparatus placed in the vicinity.

These characteristics have made it possible for the V-Contact VSC

contactors to pass the electromagnetic compatibility tests (EMC)

and obtain the CE mark.