FORM 2
THE PATENT ACT 1970
&
The Patents Rules, 2003
COMPLETE SPECIFICATION (See section 10 and rule 13)
1. TITLE OF THE INVENTION:
Tripping System for Moulded Case Circuit Breaker
2. APPLICANT:
{a} NAME: Larsen & Toubra Limited
(b) NATIONALITY: Indian Company registered under the
provisions of the Companies Act-1956.
(c) ADDRESS: LARSEN & T0UBR0 LIMITED,
L&T House, Ballard Estate, p. 0. Box: 278, Mumbai 400 001, India
3. PREAMBLE TO THE DESCRIPTION:
COMPLETE
The following specification particularly describes the invention and the manner in which it is to be performed.

Tripping System for Moulded Case Circuit Breaker
Field of the invention
The present invention relates to moulded case circuit breakers (MCCB), and more particularly, to tripping system for the moulded case circuit breakers.
Background of the invention
The circuit switching devices and circuit interrupters such as moulded case circuit breakers (MCCB) are generally known to couple to a release units such as a thermal-magnetic release and a microprocessor based release, for providing overload and short circuit protections. Those releases are mechanically coupled together and with the MCCB basic unit and are provided by actuating means for actuating the operation of the electrical device, for example, opening or closing of a circuit and the like.
Conventionally, for accounting trip of the MCCB, a flux shift device is relayed from the microprocessor based release unit. The flux shift device exerts an impact force on a latch of the MCCB mechanism to de-latch it and subsequently trip the MCCB by opening the contacts of the MCCB. However, the flux shift device used conventionally occupies a huge chunk of space and draws significant amount of power for operation.
A need therefore exist for providing a tripping system for MCCB which overcomes the above and various other limitations/drawbacks of the prior art.
Objects of the invention
An object of the present invention is to reduce requirement of space for tripping mechanism thereby reducing cost of a tripping system of the MCCB.

Another object of the present invention is to reduce power consumption for tripping the MCCB.
Summary of the invention
Accordingly, the present invention provides a tripping system for moulded case circuit breaker. The tripping system comprises a micro-processor based release connected to a tripping unit, a shape memory alloy acting as interface between the microprocessor release and a tripping unit, a spiral heater component enclosing the shape memory alloy for heating the shape memory alloy on receiving current from the trip unit, and a spring capable of communicating with the shape memory alloy and the MCCB for tripping the MCCB on receiving a trip signal from the microprocessor based release. Upon receiving a current from the trip unit, the shape memory alloy heats up and change the shape thereof which leads to actuation of the spring for tripping the MCCB mechanism.
Brief description of the drawings
Figure 1 shows a forming of a shape memory alloy;
Figure 2 shows a block diagram of shape memory alloy tripper in a moulded case circuit breaker, in accordance with the present invention;
Figure 3 shows a circuit diagram for tripper, in accordance with the present invention;
Figure 4 shows operating mechanism of the shape memory alloy tripper, in accordance with the present invention.
Detailed description of the invention

The foregoing objects of the present invention are accomplished and the problems and shortcomings associated with the prior art. techniques and approaches are overcome by the present invention as described below in the preferred embodiments.
The present invention provides a tripping system for moulded case circuit breaker. It is known that shape memory alloys have a memory effect to toggle between two or more shapes upon changing the temperature of the material. This feature of shape memory alloys is used as a part of the micro-processor based release with indispensable or factory mounted tripping unit. The shape memory alloys is an alternative for precise mechanical action for tripping with lesser space occupancy and manufacturing ease.
Referring now to figure 1- 4, there is shown a tripping system (100) for moulded case circuit breaker (MCCB), in accordance with the present invention. The system (100) includes a micro-processor based release (10), tripping mechanism (20) involving a shape memory alloy, a circuit breaker mechanism (30). a spiral heater component (not shown) and a spring (not shown).
The shape memory alloy (30) (hereinafter the SMA (30)) changes its shape upon passing electric current therethrough due to Joule's heating effect and has an expansion coefficient of greater that 30%. The (SMA) (30) along with an impulsive spring mechanism forms a device for tripping the MCCB over a trip signal from the release. Figure 1 illustrates the shape memory alloy effect.
The SMA (30) as shown in figure 2 acts as the interface between the microprocessor release (10) and the circuit breaker tripping mechanism (30) and performs the tripping action of the MCCB.

In an embodiment, to supply power to the shape memory alloy (30), a capacitor discharge is used. Specifically, a solid state switch is operated by the microprocessor release (10) to supply power to the shape memory alloy (30). Figure 3 shows a circuit diagram of the tripping system (100) with (A' representing input to the SMA (30) device.
Specifically, the current required to produce the heating is supplied by the trip unit (20). The spiral heater component (not shown and numbered) encloses the SMA (30), for heating the SMA (30). The spiral heater component enhances the impact of actuation of the SMA (30) and helps retain the thermal memory therein.
The SMA (30) actuation is used to operate the MCCB mechanism, as shown in Figure 4. Specifically, the spring communicates with the SMA (30) and the MCCB for tripping the MCCB on receiving a trip signal from the microprocessor based release (10). Upon receiving a current from the trip unit, the SMA (30) heats up and change the shape thereof which leads to actuation of the spring for tripping the MCCB.
Advantages of the invention
1. The shape memory alloy (30) used in the tripping system (100) provides precise mechanical action with lesser space occupancy and manufacturing ease.
2. The tripping system (100) has smaller design envelope, larger displacements when compared to bimetals, larger recovery force, less weight, noiseless operation and reduced energy requirements.
The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the present invention to the precise forms

disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the present invention and its practical application, to thereby enable others skilled in the art to best utilize the present invention and various embodiments with various modifications as are suited to the particular use contemplated. It is understood that various omission and substitutions of equivalents are contemplated as circumstance may suggest or render expedient but such are intended to cover the application or implementation without departing from the spirit or scope of the present invention.

We claim
1. A tripping system for moulded case circuit breaker, the tripping system comprising:
a micro-processor based release connected to a tripping unit,
a shape memory alloy acting as interface between the microprocessor release and a tripping unit,
a spiral heater component enclosing the shape memory alloy for heating the shape memory alloy on receiving current from the trip unit;
a spring capable of communicating with the shape memory alloy and the MCCB for tripping the MCCB on receiving a trip signal from the microprocessor based release; and
wherein, upon receiving a current from the trip unit, the shape memory alloy heats up and change the shape thereof which leads to actuation of the spring for tripping the MCCB mechanism.