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Siemens 38-3AH3 38 kV Instruction Manual page 31

Vacuum circuit breaker
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Relay tripping may also be achieved by
employing a normally open contact in
parallel with the holding coil. If this
scheme is used, a resistor must be
provided to limit current when the
normally open contact is closed.
Secondary and undervoltage releases are
available for all standard ANSI/IEEE control
voltages.
Construction and mode of operation of
secondary release and undervoltage
release
Refer to Figure 23: Construction of
secondary shunt release (shown charged)
and Figure 24: Latch details (shown
charged) on page 30 and Figure 25:
Undervoltage lock/operate selection on
page 31.
The release consists of a spring power-
storing mechanism, a latching device and
an electromagnet. These elements are
accommodated side-by-side in a housing
(3.0), with a detachable cover and three
through-holes (5.0) for fastening screws.
The supply leads for the trip coil are
connected to a terminal block (33.0).
The energy-storing mechanism consists of
the striker pin (23.0) and its operating
spring (31.0), which is mostly located
inside the striker pin (23.0). When the
spring is compressed, the striker pin is held
by a latch (25.0), whose sloping face is
forced against the appropriately shaped
striker pin (23.0) by spring (27.0). The
other end of the latch (25.0) is supported
by a partly-milled locking pin (21.0) (refer
to Figure 24: Latch details (shown
CHARGED) on page 30), that pivots in the
cover sheets of the magnet armature (9.0).
The armature (9.0) pivots in front of the
poles of the U-shaped magnet core, (1.0)
and is pulled away from it by the tension
spring (11.0).
If the magnet coil (7.0) of the shunt
release 3AX1101 is energized by a trip
signal, or if the tripping pin (15.0) is
mechanically actuated, magnet armature
(9.0) is swung against the pole faces.
Vacuum interrupter/
operator
Position A: locked
23.0
29.0
Position B: unlocked (operating position)
23.0
29.0
Cancel the lock for the undervoltage release by shifting the locking screw (29) from
A to B.
23.0 - Striker pin
29.0 - Screw
120 or 240 Vac
supply
A
B
A
B
Figure 25: Undervoltage lock/operate selection
01
T
SD5
24
52o
23
A1
(+)
52T
1
(-)
A2
34
2
52o
(+)
33
(-)
Capacitor trip
Figure 26: Capacitor-trip device
Capacitor
Resistor
Rectifier
31

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