Siemens vacuum circuit breaker 38-3AH3 38 kV - Manual (Page 30)

Vacuum interrupter/
operator
Figure 23: Construction of secondary shunt release (shown charged)
23.0
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 (factory-set) screw
for 11.0
Indirect releases (dual-trip or
undervoltage) (optional)
The indirect release provides for the
conversion of modest-control signals into
powerful mechanical-energy impulses. It is
primarily used to trip medium-voltage
circuit breakers while functioning as a
secondary (dual-trip) release or
undervoltage-release 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 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).
Secondary shunt release (optional)
(54.2)
A secondary shunt release (second trip
coil) is used for electrical tripping 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 (optional) (54.2)
The undervoltage release 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 an undervoltage-
device holding-coil.
Figure 24: Latch details (shown charged)
15.0 - Tripping pin
21.0 - Locking pin
23.0 - Striker pin
25.0 - Latch
27.0 - Spring
31.0 - Striker-pin spring
33.0 - Terminal block
13.0
9.0
15.0
5.0
3.0
11.0
21.0 25.0 27.0
7.0
31.0
33.0
1.0
21.0 - Locking pin
23.0 - Striker pin
25.0 - Latch
27.0 - Spring
29.0 - Lower connection terminal
23.0 25.0
29.0
21.0 27.0
Locked/unlocked selection screw
(undervoltage release only)
30