5
5. Working principle
5.1 Working principle of fuse vacuum contactor combination apparatus
CR193 vacuum contactor is a kind of high voltage electrical apparatus which is mainly used to switch
on and off the load current. The power circuit can be connected and broken by vacuum interrupter.
The fuse vacuum contactor combination device is mainly composed of high-voltage current limiting
fuse, contactor and chassis car. Its basic working principle is: the normal start and stop of load depends on
the contactor, which also has the task of breaking part of load current, making full use of the long mechanical
life and frequent operation of the contact, and the more serious load current or short circuit The current
breaking task is completed by high voltage current limiting fuse, which makes full use of the current limiting
characteristics of fuse and the advantage of large expected breaking current. Combine and connect the two
parts, connect them to the switch cabinet in the way of plum contact, and connect the secondary control
circuit of the switch cabinet through the secondary plug. They can cooperate with each other, give full play
to their advantages and avoid disadvantages, so that the F-C circuit has some characteristics different from
other equipment, such as small rated current, large breaking current, frequent operation and long
mechanical life.
Closing
When the contactor receives the closing command, for the mechanical vacuum contactor, the coil of
the closing relay is energized, the normally open contact is closed, the circuit of the closing coil is energized,
and the operating mechanism acts, that is, the closing electromagnet under the action of electromagnetic
force drives the insulation rocker to rotate clockwise, and the screw of vacuum interrupter is pushed to
make linear motion through the contact pressure spring. Then, the moving contact and the fixed contact
are closed, at the same time, the contact spring generates the required contact stroke (i.e. overtravel), so
as to ensure the required pressure between the moving contact and the fixed contact.
For the mechanical vacuum contactor, there is a mechanical closing latch to make the contactor in the
closing state.
For the electric vacuum contactor, the electric holding module outputs stable current to keep the
closing state.
For combined electrical apparatus, three-phase fuse must be installed, and it can complete the closing
action only when it meets the unfused state.
Opening
When the contactor receives the opening command, for the mechanical vacuum contactor, the opening
relay coil is energized, the normally open contact is closed, the opening coil circuit is on, and the opening
tripping mechanism acts, that is, under the action of electromagnetic force, the opening electromagnet
drives the roller out of the lock, the opening spring drives the electromagnetic operation mechanism to act,
and drives the insulation rocker to rotate anticlockwise. Pull the bolt of the arc extinguishing chamber to
separate the moving contact from the static contact at a proper speed. The buffer pad will work near the
final opening position and absorb the residual kinetic energy of the opening, thus completing the whole
opening process.