FIELD OF INVENTION
The present invention relates to a circuit breaker. More particularly, the present
invention relates to an insulating nozzle for dual motion interrupters used in a circuit
breaker.
A Circuit Breaker (CB) is primarily used to interrupt normal/fault/capacitive/inductive
currents of high voltage power transmission and the distribution systems. When the
circuit breaker is in closed condition it allows flow of normal electrical charge (current)
through a closed electrical system (circuit). The magnitude of current is governed by
the system characteristics and state. Short circuits, causing abnormal flow of current,
are sensed by current sensors and prevented by isolating the source and the load by
circuit breakers.
BACKGROUND OF THE INVENTION
When a fault current is interrupted by an interrupter, an arc is struck between the
arcing contacts. The energy current of the arc depends on the current magnitude,
length of the arc and similar other parameters. As the temperature of the arc is quite
high it decomposes the insulating medium (gas) and materials exposed to arc.
Byproducts of the chemical reaction at elevated temperature also accumulate in the

vicinity destabilize insulation and shall be removed for sustaining the dielectric
properties of the inter-electrode gap for subsequent interruptions.
In the conventional interrupters one out of the two contacts is fixed, during interruption
the moving contact is driven by operating mechanism and an arc is struck on contact
separation (Fig.l (a)). At current-zero the arc is extinguished naturally exposing the
developed inter-electrode gap to system and transient recovery voltages. The gap
reignites or the arc is re-struck should the gap fail to withstand these voltages. For
mechanical constraints limited inter-electrode gaps only can be generated in
conventional interrupters, promoting use of multiple breaks for EHV circuit breakers. Up
to 245 kV single-break circuit breaker designs are common, beyond this rating two or
more breaks are used in series to form a circuit breaker. The multiple breaks require
voltage equalizing devices like grading capacitors etc., affecting circuit breaker reliability
and cost.
Prior art:
An US Patent No. 20080257866A1 discloses to limit the voltage appearing across the
contacts during interruption, multiple breaks are preferred. The multiple break systems
are operated by same drive which requires higher energy drive for its operation. To
overcome this problem, a dual motion contact system has been identified as an
alternative solution (Fig. 1(b)). However, in all these systems, the second movable
contact i.e., other than primary moving contact takes sufficient portion of energy from
the operating mechanism. In some of the conventional breakers, such system have

relatively high energy requirements and are difficult to operate with low energy
mechanisms.
The electrostatic field, between movable and fixed contacts, is non-uniform for various
reasons like electrode profile and relative position of contacts. The field intensification
adversely affects voltage withstanding capabilities of the gas gap. The availability of hot
and conducting gas further complicates the situation preventing successful interruption.
In most of the interrupters, the arced gas after leaving the nozzle may spill out into the
contact system due to improper channeling and this may lead to thermal failures.
Beyond particular instant of time during current interruption, minimum arcing time is
decided by the effectiveness with which arcing' gas is being removed across inter-
electrode gas gap and uniformity of the electrostatic field between arcing contacts. To
overcome this problem, creepage length of nozzle is increased by different ways.
Nevertheless performance of the system is limited and none of the interrupters is
utilized to full capabilities.
Additionally the conventional single break interrupters use the concept of connecting of
second movable contact system to the main drive through insulating rods. This may
lead to increased electrostatic stress concentration across inter-electrode gap and hence
voltage withstand capabilities of the system are limited. To overcome this constraint
and to achieve desired interrupter performance excess quantity of gas are practiced by
designers.
For successful interruption, the primary design requirements are sufficient inert-
electrode gap; optimal dielectric properties of the gas and field uniformity in inter-

electrode gap. To address some of these requirements, a movable shield approach has
been innovated and notified, vide patent application no. 290/KOL/2009. Interrupting
capability of the breaker is further improved by means of a novel relative motion of
contact system with a charging and toggling mechanical system for pin (second
movable contact) vide patent application no. 1391/KOIV2009.
OBJECTS OF THE INVENTION
The main objective of invention is to improve interrupting performance of higher
voltage circuit breakers by:
• Reduction of breaks per pole for circuit breakers of higher voltage class.
• Timed relative motion/dual motion contact system and accelerated contact
separation.
• Operation of dynamic contact system by consuming little energy from the drive.
• Optimizing inter-electrode gap for interrupter voltage class and interrupting
capacity.
• Protection of inter-electrode gap from hot/conducting gas contamination and
improved gas exhaust system.
• Realization of a common drive for the interrupter accomplishing above.
• Operation of second movable contact through insulating nozzle.
• Design of nozzle to be part of moving system and suitable for high speed
operation.

• Integration of nozzle to the moving contact assembly in self locked manner.
• Dual motion contact system with second moving contact coupled to nozzle
through a novel mechanical arrangement and energy storage device.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Fig.1 - Conventional interrupters
Fig.2 - Socket contact Assembly
Fig.3- Arrangement of pin with reference to static current carrying contact assembly.
Fig.4 - Integration of nozzle to socket contact assembly.
Fig.5 - Arrangement of Invented nozzle coupled to pin.
Fig .6 - Invented interrupter with integrated nozzle and relative/dual motion contact
system.
Fig.7 - shows a sectional view of the nozzle.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE
INVENTION
As shown in Fig.2, the socket contact assembly comprises one socket (01), made of a
high conductivity and low erosion material is held on a socket support (02). The socket
(01) is covered by a socket contact shield (03) made from erosion refractory material.
The nozzle (05) is fixed to dynamic current carrying (CC) contact (04) and to the socket

contact assembly. The socket (01), contact shield (03) and current carrying contact (04)
are termed as the socket contact assembly.
The interrupter when fully open condition, the pin (06) or second movable contact is
surrounded by a dynamic field electrode (07). The pin (06) is located inside the
dynamic field electrode and the arrangement is again inside the stationery current
carrying (CC) contact assembly. The pin (06) is dimensioned such that it promoted
uniform electrostatic field between the two arcing contacts.
Fig.3 shows the arrangement of pin with reference to static current carrying contact
assembly. The static current carrying contact assembly comprising static current
carrying (CC) contact (08) and static current carrying contact shield (09). The
interrupter when in open condition, the dynamic field electrode (07) projects out from
the static current carrying contact shield (09) and the gas gap between dynamic filed
electrode and dynamic current carrying contact (04) decides the withstand voltage.
Conventionally, the second movable contact system is engaged to the main drive using
insulating rods which may affect the electrostatic field across the inter-electrode gap. In
order to improve the electrostatic field across the inter-electrode gap, an insulating
nozzle has been made in such a way that the second movable contact/pin (06) is
engaged to the main drive through nozzle. The proposed nozzle provides good
mechanical strength against electro-mechanical forces. Proposed nozzle has two
terminals. First terminal is integrated to primary moving contact assembly/socket
contact assembly. Alternatively, the nozzle is connected to socket contact assembly in
self locked manner which helps to work against mechanical forces. Fig.4 shows the

nozzle integrated to socket contact assembly. The second terminal of the nozzle is
coupled to the pin through a mechanical arrangement and an energy storage device.
The second terminal of the nozzle is at a fixed potential rather than at floating potential
as in the some of the conventional systems.
The profile of nozzle proposed in the patent has been optimized by considering
following aspects:
1. Uniform electrostatic field across main current carrying contacts (the socket
contact assembly and static current carrying contact assembly) and arcing
contacts (pin and socket).
2. The socket contact system, dynamic field electrode (07) and the coupling system
are arranged in such a way that at minimum arcing time the hot gas is vented to
main volume through the nozzle, preventing stagnation/occupation of hot gas in
the inter-electrode gap of the contact system.
3. There is no communication of hot/ionized gas from arcing contacts to the gas
gap between socket contact system and static current carrying contact assembly.
Hence withstandable voltage or field uniformity between main current carrying
parts will not get disturbed during fault current interruption. In other words,
spilling of ionized gas from nozzle vent into gas gap across main current carrying
contacts is totally removed.
4. The profile of nozzle is such that the push from arcing energy to the pin along
with the energy stored in the pin helps in achieving required arcing contact
separation in few milliseconds.

Fig.5 shows the invented nozzle coupled to pin through mechanical arrangement.
The nozzle is connected to motion guide (10) through suitable couplers known as
charging links (11) which in turn controls the movement of dynamic field electrode
(07). The dynamic field electrode is clamped to motion guide by means of guide
rods (12). The charging link (11) has a guiding slot whose length is related to the
stroke of breaker and distance by which pin (06) travels. The pin is compressed
against damper/energy storage device (13) force and guided by current collector
(14) when the CB is in open condition. The pin (06) is connected to the charging link
(11) through a mechanical arrangement (15). This arrangement helps the pin (06)
to engage permanently with socket assembly and does not allow the pin to move
independently. At a particular instant of closing operation, the mechanical
arrangement (15) comes into operation and the pin guided by damper (13) gets
compressed. This in turn results in movement of pin and storage of spring energy in
the damper. Once breaker is closed, the toggle between mechanical arrangement
(15) and charging link (11) ensures pin location; the toggle is reactivated by open
command of the interrupter.
During opening operation, the pin (06) is initially held by the socket (01), friction
between pin and socket. The pin or release from socket moves at a speed decided
by energy stored, mass of the pin and friction offered by current collector (14). As
the travel of the pin is controlled, pin acts as a static contact beyond this travel.
Once contact separation is made, the arc struck between the contacts generated
sufficient pressure force to push the pin as it seals the expansion volume (16)

during arcing period. The available pressure force increases with increase of arcing
current as the expansion volume is not communicated to puffer volume (17). Hence
pressure force along with the stored energy in the pin increase the speed of the pin
during arcing period and help in achieving required contact separation at faster rate
and control the minimum arcing time. The travel of the pin is set in conjunction with
speed of socket to suit; initial TRV, TRV and power frequency withstand
requirements. The distance to which pin (06) is displaced can be adjusted by
modifying the design parameters of mechanical arrangement (15) as well as the
energy storage device. Once opening operation is completed, the pin is coupled to
the charging link through mechanical arrangement in such a way that it can not
operate on its own.
Fig.6 shows the invented interrupter with integrated nozzle and a relative
motion/dual motion contact system in closed condition wherein relative motion
system in which pin (06) operated on its own during current interruption. The
necessary energy required for this movement is stored/gained during preceding
closing operation. It is the novelty of the design that the pin is again under the
control of primary moving contact/socket contact system and insulated nozzle (05)
through mechanical arrangement (15) and energy storage device (13). Hence,
proper closing and opening of the contact system are ensured. The speed of pin is
designed based on dielectric recovery requirements of the interrupter at minimum
arcing time.

WE CLAIM
1. An insulating nozzle for dual motion interrupter impregnated in a circuit breaker
comprises:
- a taper cylindrical outer shape having a first terminal end with a "Y"
shaped hollow inside and a second terminal end with a conical shaped
hollow inside part;
- a wavy configuration in the middle part of the outer surface and a wavy
configuration in the inside surface at the junction of "Y" shaped hollow
part of first terminal and the conical shaped hollow part of the second
part;
- an outside protruded part of the first terminal end integrated with self
locking with the socket contract assembly;
- an outside protruded part at the second terminal end is coupled to the pin
through a mechanical arrangement and an energy storage device (13);
characterised in that during fault current flow inside the nozzle, arc is
struck between the contracts generate sufficient pressure force to push
the pin from main device at a faster rate and control minimum arcing time
without communication of hot ionized gas from arcing contacts to the gas
gap between main/current carrying contacts wherein the pin is reset with
charging link through mechanical arrangement for closing the circuit
breaker for restart.

2. The insulating nozzle as claimed in claim 1, wherein the insulating nozzle is made
of a high resistivity and low erosion material.

The present invention relates to an insulating nozzle for dual motion interrupter
impregnated in a circuit breaker comprises a taper cylindrical outer shape having a first
terminal end with a "Y" shaped hollow inside and a second terminal end with a conical
shaped hollow inside part and a wavy configuration in the middle part of the outer
surface and a wavy configuration in the inside surface at the junction of "Y" shaped
hollow part of first terminal and the conical shaped hollow part of the second part and
an outside protruded part of the first terminal end integrated with self locking with the
socket contract assembly and an outside protruded part at the second terminal end is
coupled to the pin through a mechanical arrangement and an energy storage device
(13) characterised in that during fault current flow inside the nozzle, arc is struck
between the contracts generate sufficient pressure force to push the pin from main
device at a faster rate and control minimum arcing time without communication of hot
ionized gas from arcing contacts to the gas gap between main/current carrying contacts
wherein the pin is reset with charging link through mechanical arrangement for closing
the circuit breaker for restart.