Siemens 3AH3 Instruction Manual page 25

Indirect releases - secondary shunt
release (dual trip) (52T1) or undervoltage
(27.0)
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 applicable control voltages
(refer to Figures 15, 16 and 17).
The secondary shunt-release and
undervoltage release mounts to the
immediate right of the trip coil (54.1).
Secondary shunt-release (52T1) (refer to
Figure 15)
A secondary shunt-release (extra-trip coil)
(3AX1101) is used for electrical 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 (27.0) (refer to
Figures 16 and 17)
The undervoltage release (3AX1103) is used
for continuous monitoring of the tripping
supply voltage. If this supply voltage 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 holding 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/IEEE
control voltages.
23.0
13.0
15.0
6.0
3.0
Item Description
1.0 Magnet core
3.0 Housing
6.0 Mounting holes
7.0 Magnet coil
9.0 Magnet armature
11.0 Tension spring
13.0 Adjusting screw (factory set) for 11.0
Figure 15: Construction of secondary shunt release (shown charged)
23.0
Item Description
21.0 Locking pin
23.0 Striker pin
25.0 Latch
31.0
27.0
25.0
21.0
11.0
7.0
9.0
Item
15.0
21.0
23.0
25.0
27.0
31.0
33.0
29.0
27.0
25.0
21.0
Item
25.0
Undervoltage enable/disable set-
29.0
ting screw (undervoltage only)
Figure 16: Latch details (shown charged)
33.0
1.0
Description
Tripping pin
Locking pin
Striker pin
Latch
Spring
Striker-pin spring
Terminal block
Description
Latch
25