Indirect Releases (Secondary Shunt Release (Dual Trip) (52T1) Or Undervoltage (27)); Secondary Shunt Release (52 T1) (Figure 11); Undervoltage Release (2 7) (Figures 10 And 11); Construction And Mode Of Operation Of Secondary Shunt Release And Undervoltage Release (Figures 11. 12 And 13) - Siemens 3AH Series Instructions Manual

Vacuum circuit breaker operator module
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Vacuum Interrupter/Operator Description
Close coil ( 52SRC)
The close coil (3AY1 510) is a standard component of the
circuit breaker which is used to unlatch the stored energy of
the closing spring and thus close the circuit breaker elec­
trically. It is available for both AC and DC operation. After
com pletion of a closing operation, the close coil is de-en­
ergized internally. If operated with AC voltage, a rectifier is
insta l led in the circuit breaker.
Trip coil (52T)
The trip coil (3AY1 510) is a sta ndard component of the ci rcuit
breaker. The electrically supplied tripping signal is passed on
to the trip latch ing mecha nism by means of a d i rect action
solenoid armature and the circuit beaker is thus opened. It is
availabl e for both AC a n d DC operation. After completion of
an opening operation, the trip coil is de-energized i nternally.
If operated with AC voltage, a rectifier is installed in the
circuit breaker.
Indirect Releases (Secondary Shunt Release (Dual Trip)
(52T1) or Undervoltage (27))
The indirect release provides for the conversion of modest
control signals into powerful mechanical energy i m pulses.
It is primarily used to open medium voltage circuit breakers
while functioning as a secondary shunt release (dual trip) or
undervoltage device.
These releases a re mechanical energy storage devices.
Their internal springs a re charged as a consequence of
the circuit breaker mechanism operatio n . This energy is
released upon application or removal (as appropriate) of ap­
plicable control voltages. Refer to Figures 11, 12 and 1 3.
The Secondary shunt release and U n dervoltage release
mounts to th e immediate right of the trip coil (54.1 ).

Secondary Shunt Release (52 T1) (Figure 11)

A secondary shunt release (extra trip coil) is used for electri­
cal opening of the circuit breaker by protective relays or
ma nual control devices when more th an one trip coil is
required. The second trip coil is genera lly connected to a
separate auxiliary supply ( DC or AC) from the control supply
used for the normal trip coil. U ndervoltag e Release (27)
( Figures 12 a n d 1 3) .

Undervoltage Release (2 7) (Figures 10 and 11)

The undervoltage release (3AX1103) is used for continuous
monitoring of the tripping supply voltage. If this supply volt­
age falls excessively, the undervoltage release wil l provide
for automatic tripping of the circuit breaker.
The undervoltage device may be used for manua l or relay
tripping by em ploying a contact in series with undervolta g e
device holding coil. Relay tripping m a y a lso b e achieved by
employing a normally open contact in parallel with the hold­
ing coi l. If this scheme is used, a resistor must be provided
to limit current when th e normally open contact is close d .
Secondary shunt and undervoltage releases are available for
all standard ANSI control voltages.
11 21 25 27
1 Magnet core
3 Housing
5 Mounting holes (3)
7 Magnet coil
9 Magnet armature
11 Tension spring
13 Adjusting (Factory set)
screw for 11
Figure 11. Construction of Secondary Shunt Release (shown
charged).
Construction and Mode of Operation of Secondary
Shunt Release and Undervoltage Release (Figures 11,
1 2 and 1 3)
The release consists of a spring-power stori ng m echanism,
a latching device, and a n electromagnet. These elements a re
accommodated side by side in a housing (3), with a detach­
able cover a n d three through holes (5) for fastening screws.
Th e supply leads for the trip coil are connected to a terminal
block (33).
The energy-storin g mechanism consists of the striker pin
(23) a n d its operati ng spri ng (31 ), which is mostly located
inside the striker pin (23). Wh en the spring is compressed,
the striker pin is held by a latch (25), whose sloping face is
forced against the a ppropriately shaped striker pin (23) by
spring (27). The other end of the latch (25) is supported by a
partly milled locki ng pin (21 ), pivoted in the cover sheets of
the magnet a rmature (9). The armature (9) is pivoted in front
of the poles of the U-shaped mag net core, ( 1 ) a n d is pulled
away from it by the tension spring (11 ).
If the magnet coil (7) of the seconda ry shunt release 3AX1101
is energ ized by a trip signal, or if the tripping pin ( 1 5) is me­
cha nically actuated, magnet armature (9) is swung against
the pole faces. When this happens, the latch (25) loses its
support and releases the striker pin (23), which is forced out
by the spring (31 ).
7
31
1 5Tripping pin
21 Locking pin
23 Striker pin
25 Latch
27 Spring
31 Striker pin spring
33Terminal block
1 94-94
17

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