Undervoltage Release; Construction And Mode Of Operation Of Secondary; Release And Undervoltage Release (See Figures 9, 10 And 11); Capacitor Trip Device - Siemens 3AH Instructions, Installation, Operation, Maintenance

Interrupter/Operator Description

Undervoltage Release

The undervoltage release is used for continuous monitor-
ing of the tripping supply voltage. If this supply voltage
falls excessively, the undervoltage release will provide for
automatic tripping of the 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 and undervoltage releases are available for all
standard ANSI control voltages.

Construction and Mode of Operation of Secondary

Release and Undervoltage Release
(See Figures 9, 10 and 11)
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
detachable cover and three through holes (5) for fastening
screws. The supply leads for the trip coil are connected to
a terminal block (33). Two lugs (17) are provided beside
the tripping pin (15) for the attachment of a manual trip-
ping lever.
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) (see Figure 9), pivoted in
the cover sheets of the magnet armature (9). The arma-
ture (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 shunt release 3AX1101 is ener-
gized by a trip signal, or if the tripping pin (15) is mechani-
cally actuated, magnet armature (9) is swung against the
pole faces. When this happens, the latch (25) loses its sup-
port and releases the striker pin (23), which is forced out
by the spring (31).
On the undervoltage release 3AX1103, the latch (25) is held
by the locking pin (21) as long as the armature (9) is at-
tracted (See Figure 10). If the circuit of the magnet coil (7)
is interrupted, the armature (9) drops off, thus causing the
latch (25) to lose its support and release the striker pin (23).
Following every tripping operation, the striker pin (23) must
be reset to its normal position by loading the spring (31).
This takes place automatically via the operating mecha-
nism of the circuit breaker.
Since the striker pin of the undervoltage release 3AX1103
is latched only when the armature is attracted, this trip is
provided with a screw (29) (see Figure 11), for locking the
striker pin (23) in the normal position for adjusting pur-
poses or for carrying out trial operations during breaker
servicing. Position A (blocked) disables the undervoltage
release. Position B is the normal (operating) position.
23 11 21 25 27
13
9
15
5
3
1 Magnet core
2 Housing
5 Mounting holes (3)
7 Magnet coil
9 Magnet armature
11 Tension spring
13 Adjusting screw for 11
Figure 9. Construction of Shunt Release (shown released)

Capacitor Trip Device

The capacitor trip device is an auxiliary tripping option (ca-
pacitor trip is a system that should be mounted on the
drawout truck) providing a short term means of storing
adequate electrical energy to ensure breaker tripping.
This device is applied in breaker installations lacking inde-
pendent auxiliary control power or station battery. In such
installations, control power is usually derived from the pri-
mary source. In the event of a primary source fault, or
disturbance with attendant depression of the primary
source voltage, the capacitor trip device will provide short
term tripping energy for breaker opening due to relay op-
eration.
The capacitor trip converts 120 or 240 VAC control volt-
age to a DC full wave voltage which is used to charge a
large capacitor to the peak of the converted wave. See
Figure 12.
31
7
33
1
15 Tripping pin
21 Locking pin
23 Striker pin
25 Latch
27 Spring
31 Striker pin spring
33 Terminal block
1294-94
13