Closing Procedure; Auto-Reclosing Sequence; Opening Procedure; Quenching Principle Of The Vacuum Interrupter - ABB VD4X Instruction Manual

16 V D 4 X I N S T R U C T I O N M A N U A L
pumping action with charging lever 32,
depending on the equipment fitted to the
circuit-breaker. The charging condition is shown
by mechanical charging condition indicator 8.
As a precondition for an auto-reclosing sequence,
the mechanism is automatically (re-)charged
after a closing operation by the charging motor.

3.3.2 Closing procedure

The closing process is started by activation of
shunt release ON -Y3, or by the mechanical ON
push-button. The release mechanism 24 then
per mits mechanism shaft 27 to be rotated
by the (previously) charged spiral spring. The
moving con tact 15.3 in vacuum interrupter 15 is
moved by cam disc 28 and further kinematic
links until the contacts touch. In the further
sequence of motion, spring arrangement 16 is
tensioned and the approp riate amount of
contact force thus applied. The available
overtravel is greater than the maximum contact
erosion during the service life of the vacuum
interrupter. During the closing process, opening
springs 25 are simultaneously tensioned.

3.3.3 Opening procedure

The opening procedure is initiated by activation
of one of releases -Y2, -Y4, -Y7 or -Y9 or by
mechanical OFF push-button 3. Release
mechanism 24 then permits mechanism shaft 27
to be turned further by the spiral spring, which
is still sufficiently charged. The opening spring
25, which is thus released, moves the contact 15.3
into the open position at a def ined speed.
Notes on activation of the releases
1. Only shunt release OFF (-Y2 and -Y9) and
shunt release ON (-Y3) are provided for
operational opening and closing.
These three releases are rotary magnets, and
are suitable for a high number of operating
cycles.
2. The undervoltage release (-Y4) or the indirect
overcurrent release (-Y7) are purely
safety/protective tripping units and must not
be used for operational switching.

3.3.4 Auto-reclosing sequence

An OFF-ON or OFF-ON-OFF auto-reclosing
sequence is activated and monitored by the
protection system. It is necessary for the spiral
spring in the operating mechanism to be in the
(re-)charged cond ition, with the circuit-breaker
in the closed position. The (re-)charging process
is carried out auto mat ically by the charging
motor after closing of the breaker. If the charging
motor breaks down, the charging process can
be carried out or completed manually. Opening
of the breaker is also possible during the
(re-)charging process, but subsequent closing
of the breaker is however blocked until the
charging process has been completed.
3.3.5 Quenching principle of the vacuum
interrupter
Due to the extremely low static interrupter
chamber pressure of <2x10
relatively small contact gap is required to
achieve a high dielectric strength. The vacuum
arc is extinguished on one of the first natural
current zeros.
Due to the small contact gap and the high
conductivity of the metal vapour plasma, the
arc drop voltage, and additionally, due to the
short arcing time, the associated arc energy,
are extremely low, which has advantageous
effects on the life of the contacts and thus on
that of the vacuum interrupters.
hPa, only a
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