Quenching Principle Of The; Vacuum Interrupter; Interlocks; Interlocks/Protection Against Maloperation - ABB VM1 Instruction Manual

3.3 Quenching principle of the vacuum interrupter
Due to the extremely low static interrupter chamber
pressure of 10 -4
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.
3.4.

Interlocks

3.4.1 Interlocks/protection against maloperation

(for C.B. on withdrawable parts)

(Figure 9/10)
A series of interlocks are provided to prevent
dangerous situations and any maloperation. The
interlocks of the panel system ZS and/or the
Powerbloc/mounting frame, which are normally
effective, are as follows (concerning the circuit-
breaker):
• The withdrawable part can only be moved from
the test/disconnected position into the service
position (and back) with the circuit-breaker open
(that means that the breaker must be opened
before)
• The circuit-breaker can only be closed if the
withdrawable part is precisely in the defined test
position or service position (electrical interlock).
• The circuit-breaker can only be opened
manually in the service or test position when no
control voltage is applied, and it can not be
closed.
• The panel is equipped with devices which allow
the connection and disconnection of the control
wiring plug 36.1 only in the test/disconnected
position.
• Details of any additional interlocks, e.g. in
connection with a blocking magnet on the
withdrawable part and/or earthing switch
operating mechanism, can be found in the order
documents for each individual case.

3.4.2 Interlocks for VM1 withdrawable parts

3.4.2.1 Interlocks when ABB withdrawable assemblies
are used
(Figures 9/12, 9/29 and 10/14 to 10/17)
1.) The VM1 can only be closed via input -Y3 when
a voltage of 24 V to 240 V AC/DC is applied to
input -Y1 (electrical closing lock-out).
2.) The VM1 can only be closed when the with-
drawable assembly is in service or test position.
In the intermediate positions, the voltage for the
closing lock-out is interrupted by auxiliary switches
-S8/-S9.
to 10 -8 hPa, only a relatively small
3.) A mechanical interlock located in the with-
drawable assembly prevents a closed breaker
being moved from the test position into the
service position.
3.4.3 Interlocks when non-original withdrawable

assemblies are used

(Figures 9/29, 10/6 and 10/14 to 10/17)
VM1 circuit-breakers which are not mounted on
ABB withdrawable part must be fitted with one or
two additional auxiliary switches which are
dependent on the mechanical interlocks. These
must interrupt the input voltage to the electrical
closing lock-out (input -Y1).
In a similar manner to auxiliary switches-S8 and-S9
on the ABB withdrawable part, no further electrical
pulse may be received after the first half revolution
of spindle system 35.1, and it may only be re-
applied after the last half revolution. This ensures
that the circuit-breaker cannot be closed when the
withdrawable part is in an intermediate position.
A mechanical interlock as described in 3.4.2.1
part 3.) is to be implemented to prevent movement
of a circuit-breaker which is closed. The slide
blocker 41.2 on the VM1 (optional accessory for
stationary mounted breakers) can be used for this
purpose: if the VM1 is closed, the slide blocker is
outside base plate 41.4. Figure 9/29 shows pawl
35.5 on the ABB withdrawable part. With the
circuit-breaker closed, pawl 35.5 cannot be
rotated in the anti-clockwise direction. This
prevents movement of the withdrawable assembly
and therefore movement of the circuit-breaker.
Note:
Additionally fitted interlocks must not exert any
force on the operating mechanism of the circuit-
breaker.
If the interlock mechanism projects beyond the
base of the circuit-breaker casing, measures must
be taken to prevent the the circuit-breaker from
weighing down on the interlock, for instance during
transport.

Despatch and storage

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4.1

Condition on delivery

• The factory-assembled switching devices are
checked at the works for completeness of the
equipment installed and simultaneously sub-
jected to a routine test in accordance with
VDE 0670, part 1000 or IEC publication 60694,
thus verifying their correct structure and
function.
Storage capacitor 26 is discharged by the
connected control electronics, and has a terminal
voltage of < 10 V when delivered.
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