Close Coil (52Src); Trip Coil (52T); Indirect Releases (Secondary Shunt Release (Dual Trip) (52T1) Or Undervoltage (27)); Secondary Shunt Release (52T1) (Figure 11) - Siemens 3AH Installation Operation & Maintenance

Vacuum Interrupter/Operator Description

Close coil (52SRC)

The close coil (3AY1510) 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
completion of a closing operation, the close coil is de-en-
ergized internally. If operated with AC voltage, a rectifier is
installed in the circuit breaker.

Trip coil (52T)

The trip coil (3AY1510) is a standard component of the circuit
breaker. The electrically supplied tripping signal is passed on
to the trip latching mechanism by means of a direct action
solenoid armature and the circuit beaker is thus opened. It is
available for both AC and DC operation. After completion of
an opening operation, the trip coil is de-energized internally.
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 impulses.
It is primarily used to open medium voltage circuit breakers
while functioning as a secondary shunt release (dual trip) or
undervoltage device.
These releases are mechanical energy storage devices.
Their internal springs are charged as a consequence of
the circuit breaker mechanism operation. This energy is
released upon application or removal (as appropriate) of ap-
plicable control voltages. Refer to Figures 11, 12 and 13.
The Secondary shunt release and Undervoltage release
mounts to the immediate right of the trip coil (54.1).

Secondary Shunt Release (52T1) (Figure 11)

A secondary shunt release (extra trip coil) is used for electri-
cal opening of the circuit breaker by protective relays or
manual control devices when more than one trip coil is
required. The second trip coil is generally connected to a
separate auxiliary supply (DC or AC) from the control supply
used for the normal trip coil. Undervoltage Release (27)
(Figures 12 and 13).

Undervoltage Release (27) (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 will provide
for automatic tripping of the circuit breaker.
The undervoltage device may be used for manual or relay
tripping by employing a contact in series with undervoltage
device holding coil. Relay tripping may also be achieved by
employing a normally open contact in parallel with the hold-
ing coil. If this scheme is used, a resistor must be provided
to limit current when the normally open contact is closed.
Secondary shunt and undervoltage releases are available for
all standard ANSI control voltages.
23 11 21 25 27
13
9
15
5
3
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,
12 and 13)
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), with a detach-
able cover and three through holes (5) for fastening screws.
The supply leads for the trip coil are connected to a terminal
block (33).
The energy-storing mechanism consists of the striker pin
(23) and its operating spring (31), which is mostly located
inside the striker pin (23). When the spring is compressed,
the striker pin is held by a latch (25), whose sloping face is
forced against the appropriately shaped striker pin (23) by
spring (27). The other end of the latch (25) is supported by a
partly milled locking pin (21), pivoted in the cover sheets of
the magnet armature (9). The armature (9) is pivoted in front
of the poles of the U-shaped magnet core, (1) and is pulled
away from it by the tension spring (11).
If the magnet coil (7) of the secondary shunt release 3AX1101
is energized by a trip signal, or if the tripping pin (15) is me-
chanically 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
33
1
15 Tripping pin
21 Locking pin
23 Striker pin
25 Latch
27 Spring
31 Striker pin spring
33 Terminal block
1294-94
17