F O R M 2

THE PATENTS ACT, 1970
(39 of 1970)
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10; rule 13)

1. Title of the invention: AN IMPROVED ARRANGEMENT FOR COOLING OF ELECTRICAL SWITCHGEAR

2. Applicant(s):

(a) NAME : LARSEN & TOUBRO LIMITED
(b) NATIONALITY : An Indian Company
(c) ADDRESS : L & T House, Ballard Estate, Mumbai 400 001,
State of Maharashtra, India

3. PREAMBLE TO THE DESCRIPTION

The following specification particularly describes the invention and the manner in which it is to be performed:

FIELD OF THE INVENTION

The present invention relates to cooling and watt loss reduction in switchgear. Particularly the present invention relates to thermoelectric module which will be used in temperature control, watt loss reduction and cooling techniques. More particularly the present invention relates to an improved arrangement for cooling and watt loss reduction of electrical switchgear.

BACKGROUND AND PRIOR ART OF THE INVENTION

Switchgears are the device comprise of various electric disconnects used in electrical protection system. Switchgears isolate the faulty system from the unaffected line so to avoid the fault current reaching the healthy lines. It consists of an enclosure in which make and break of contacts take place, also it contains mechanism comprising of different links which finally cause the breaker to close or open. Current path consists of different parts which are made up of high electrically conductive material like copper. So, in the current path I2R loss and eddy current loss are prominent.

Most of the electrical devices produce heat on application of electric current. This heat energy produced leads to increase in temperature of the device. In order to achieve prolong and reliable use of such devices thermal management measures need to be taken. furthermore increase in temperature of the device beyond a safe limit is not desirable as it can damage or destroy the whole device or some part of it. So, applying some cooling techniques in such devices is necessary.

Being an electrical product some amount of energy supplied to the breaker get consumed by breaker itself, this loss is termed as watt loss. Basically there are two types of losses occurring in the breaker, hot watt loss and cold watt loss.
Cold watt loss are the watt loss measured immediately after the circuit breaker is started and the temperature of the breaker is equal to ambient temperature, while the hot watt loss are calculated 7-8 hours after circuit breaker has been started. When we supply high amount of current for long time through circuit breaker the temperature of breaker component rises. Rise in temperature cause immediate increase in resistance of various current path component as resistance is directly proportional to the temperature. So, increase in resistance will effectively increase the I2R loss.

Presently only heat sinks are used to reduce the temperature of circuit breaker but with heat sink the decrease in temperature is limited to some degrees. Using thermoelectric module with heat sink one can go below ambient too.

The input supplied to switchgear is an electric one so this electric current generate I2R losses and electric energy gets converted into thermal energy leading to heating of element of current path. Thus, hot watt loss (losses because of heating) increases.

US 7,082,772 teaches about Peltier effect module used for cooling audio system installed in vehicle. Further it relates to a cooling system for audio equipment uses a temperature sensor and Peltier effect module in a feedback control loop. The cooling system reads the temperature sensor to obtain the temperature of an audio component of the equipment, and adjusts the drive for the Peltier effect module that cools the audio component, to prevent overheating of the component. The cooling system may include an autonomous power supply that generates electric power from the audio signal driving a loudspeaker of the audio system. In another embodiment, the cooling system cools an audio component installed in a vehicle, even when the vehicle is unattended. To prevent discharge of the vehicle's battery, the cooling system employs a battery supervisor for turning the cooling system off when the battery has discharged down to a predetermined state.

US 6,055,814 teaches the method for cooling non-flow type system. It discloses an operating system to be cooled is formed as a non-flow system so that the system can be protected from contaminants which could otherwise enter the system. When the temperature in the system is above a certain level, heat in the system is absorbed by a Peltier module utilizing a Peltier effect. A convection fan forces the air that is cooled by the Peltier module throughout the system.

When the circuit breaker attains steady temperature, the average temperature of the circuit breaker rises to 102-105⁰C. Such a high increase in temperature from 30⁰C (ambient) to 105⁰ C will substantially increase the resistance of breaker to very high value. Also, according to standards, the permissible increase in temperature is limited to 80⁰C. Thus, it becomes very important to control the rise in temperature of breaker. Suggesting some thermal management mean thus becomes very crucial which most of the time does not get too much attention

The present invertors provides a way to reduce this hot watt loss by the use of a special arrangement which is comprising of Thermoelectric module (Peltier module)and heat sink.
The present inventors have attached the Thermoelectric module on the side limb of breaker adaptor so that the Peltier will absorb heat of breaker.

OBJECTS OF THE INVENTION

One object of the present invention is to overcome the disadvantages / drawbacks of the prior art.

A basic object of the present invention is to provide an improved arrangement for cooling and watt loss reduction of electrical switchgear.

Another object of the present invention is to provide an improved arrangement for reducing the temperature of the circuit breaker so that the watt loss can be minimized.

Yet another object of the present invention is to provide an arrangement which uses only two screw to fit and does not require any special tool for mounting and dismounting , thus the arrangement suggest a cheaper way of heat removal.

These and other advantages of the present invention will become readily apparent from the following detailed description taken in conjunction with the accompanying drawings.

SUMMARY OF THE INVENTION

According to one of the aspect of the present invention the system is provided an improved arrangement for cooling and watt loss reduction of multiple phase electrical switchgear , said arrangement comprising a circuit breaker assembly , said assembly comprising :
atleast one front facia means adapted to display information of various parameters, ON/OFF conditions ;
atleast one side facia means placed substantially on one of the side of said front facia means;
atleast one front housing connected with said side facia means ;
atleast one rear housing connected with said front facia means;
atleast one arc chute connected with said front housing and rear housing ;
atleast one first breaker adaptor substantially placed on the top and connected with said rear housing
atleast one second breaker adaptor substantially placed on the bottom and connected with said rear housing ;
atleast one first breaker terminal substantially placed on the top and connected with said first breaker adaptor and
atleast one second breaker terminal substantially placed on the bottom and connected with said second breaker adaptor ;
a cradle means of said circuit breaker assembly operatively connected with said circuit breaker, said cradle means comprising :
atleast one jaw means comprising
a top jaw means inserted into said first breaker adaptor of a circuit breaker assembly and
a bottom jaw means inserted into said second breaker adaptor of a circuit breaker assembly;
atleast one first cradle terminal means placed substantially on the top and operatively connected with said top jaw means ;
atleast one second cradle terminal means placed substantially on the bottom and operatively connected with said bottom jaw means ;
atleast one first cradle terminal adapter means placed substantially on the top and operatively connected with said first cradle terminal means;
atleast one second cradle terminal adapter means placed substantially on the bottom and operatively connected with said second cradle terminal means;
wherein a thermoelectric module is mounted top of said first breaker adaptor of a circuit breaker assembly , said module comprising :
a heat sink mounted on said thermoelectric module, said sink comprising plurality of fins ;
plurality screw fixing said heat sink with said thermoelectric module;
atleast one wire means connected with said module adapted to supply power to said module;
wherein said module further comprising a first side and a second side;
wherein the direction of the current flow is such that said first side is directly connected with first breaker adaptor and said second side is connected to said heat sink .
wherein said first side differs in temperature from said second side.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to an improved arrangement for cooling and watt loss reduction of electrical switchgear.

An unique arrangement of Thermoelectric module and heat sink in circuit breaker have been designed. The arrangement is easy to mount, easy to remove for cleaning purpose. The arrangement is made in such a manner that if the power to be removed exceeds current power extraction requirement, only adding the another thermoelectric module or replacing the existing module with the one having more power extraction capacity can serve the purpose.
The arrangement uses only two screw to fit and does not require any special tool for mounting and dismounting. This invention suggests a cheaper way of heat removal.

Present arrangement discloses the use of 'Peltier effect' for the cooling of electrical devices. The system hereby describes the Thermoelectric module, consisting thermoelectric couples made up of Bismuth Telluride.

Thermoelectric couples are couples (Joints) of a different type (P type and N type) doped thermoelectric material like Bismuth telluride. Thermoelectric couples exist inside the thermoelectric module and are basic working principle of thermoelectric module which causes to make one side of thermoelectric module hot and another one cold. A thermoelectric module contains a number of thermoelectric couples inside it to generate higher temperature difference between two sides. (a thermoelectric module is a combination of a number of thermoelectric couples and thermoelectric couples are inherent structure of thermoelectric module).
Thermoelectric module is based on one of the thermoelectric effect more particularly 'peltier effect' in which application of electric current will result into thermal gradient. When we apply electric current to peltier module one side of the module becomes hot while the other side gets cool. The side which absorbs heat is referred to as the 'Cold side' while the side which removes the heat out is called 'Hot side'. When we reverse the direction of current the two sides reverse their function. The hot side is connected to some heat dissipating media like heat sink while the cold side is attached to the device we want to cool. Thus, absorbing the heat of the device will decrease in temperature and so the watt loss.

According to one of the embodiment of the present invention there is provided an improved arrangement for cooling and watt loss reduction of electrical switchgear. The arrangement comprising a circuit breaker assembly, a cradle means of the circuit breaker assembly operatively connected with the circuit breaker, a thermoelectric module which is mounted top of the first breaker adaptor of a circuit breaker assembly.

The circuit breaker assembly comprising atleast one front facia means adapted to display information of various parameters, ON/OFF conditions ; atleast one side facia means placed substantially on one of the side of the front facia means; atleast one front housing connected with the side facia means ; atleast one rear housing connected with the front facia means; atleast one arc chute connected with the front housing and rear housing ; atleast one first breaker adaptor substantially placed on the top and connected with the rear housing ; atleast one second breaker adaptor substantially placed on the bottom and connected with the rear housing ; atleast one first breaker terminal substantially placed on the top and connected the the first breaker adaptor and atleast one second breaker terminal substantially placed on the bottom and connected with the second breaker adaptor .

The cradle means comprising atleast one jaw means where the jaw means comprises a top jaw and a bottom jaw ; atleast one first cradle terminal means placed substantially on the top and operatively connected with the top jaw means ; atleast one second cradle terminal means placed substantially on the bottom and operatively connected with the bottom jaw means ; atleast one first cradle terminal adapter means placed substantially on the top and operatively connected with the first cradle terminal means; atleast one second cradle terminal adapter means placed substantially on the bottom and operatively connected with the second cradle terminal means.
The top jaw means inserted into the first breaker adaptor of a circuit breaker assembly and a bottom jaw means inserted into the second breaker adaptor of a circuit breaker assembly.
The thermoelectric module comprising a heat sink mounted on thermoelectric module; plurality screw fixing the heat sink with the thermoelectric module; atleast one wire means connected with the module adapted to supply power to the module.
The module further comprises a first side and a second side.
The direction of the current flow is such that the first side is directly connected with first breaker adaptor and the second side is connected to the heat sink. The first side differs in temperature from the second side. The first side is cold adapted to absorb heat and the second side is hot adapted to remove heat.
The sink comprises plurality of fins. The arrangement further comprising plurality of fingers connected with the first breaker terminal and plurality of braids connected with the second breaker terminal adapted to assist the movement of main contact during breaking and making operations/ON/OFF operations.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING
Other features as well as the advantages of the invention will be clear from the following description.
In the appended drawing:

FIGURE 1 illustrates the complete arrangement of various components of switchgear.
FIGURE 2 illustrates the isometric view of one pole of circuit breaker showing its current path.
FIGURE 3 illustrates the front view of one pole of circuit breaker showing its current path.
FIGURE 4 illustrates the Side view of one pole of circuit breaker showing its current path.
FIGURE 5 illustrates the front view of heat sink and thermoelectric module assembly .
FIGURE 6 illustrates the back view of thermoelectric system including heat sink and thermoelectric module.
FIGURE 7 illustrates the isometric view of the heat sink and thermoelectric module assembly.
FIGURE 8 illustrates the thermoelectric module with hot and cold side with wires from supply.

DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWING

In the following detailed description, reference is made to the accompanying drawings that form a part hereof, and illustrate the best mode presently contemplated for carrying out the invention. Further functioning of the arrangement has been discussed below to describe the way it operates. However, such description should not be considered as any limitation of scope of the present system. The structure thus conceived is susceptible of numerous modifications and variations, all the details may furthermore be replaced with elements having technical equivalence. In practice the materials and dimensions may be any according to the requirements, which will still be comprised within its true spirit.

The present invention discloses the arrangement of Thermoelectric module with heat sink used to reduce the temperature of different parts of switchgears. Fig. 1 shows the switchgear in which Thermoelectric module is attached to the heat sink made up of highly thermal conductive material.

A switchgear shown in Fig. 1 has different parts like facia, housing, cradle, breaker, current path etc. (1) and (2) are the part of cooling system attached to the circuit breaker in order to reduce the temperature and thus watt loss. Breaker adaptor bottom(4b), breaker adaptor top(4a),breaker terminal bottom (8b), breaker terminal top (8a), arc chute (11), rear housing (12), front housing (13), side facia (14) and front facia (15) are the different parts of breaker assembly while jaws top and bottom(5), cradle terminal bottom (6b), cradle terminal top(6a) and cradle terminal adaptor bottom (7b) and cradle terminal adaptor top(7a) are the parts of cradle of circuit breaker (in case of draw out circuit breaker). The current flows through the current path comprises of cradle terminal adaptor top (7a), cradle terminal top (6a), jaws (5), breaker adaptor top(4a), breaker terminal top (8a), finger (9), braid (10) and back to breaker terminal bottom(8b), breaker adaptor bottom(4b), jaws(5), cradle terminal bottom (6b) and cradle terminal adaptor bottom (7b).

Front housing (13) and rear housing(12) are made up of insulating medium and serves as the covering of current path. Front facia (15) displays the information about various electrical parameters, ON/OFF condition etc. The current path for one phase of circuit breaker is shown in fig. 2 Braid (10) is the part of current path which helps in flexible movement during making and breaking of main contacts. The Thermoelectric module (1) is attached to the breaker adaptor (4a). A heat sink (2) with the help of screws (3) is mounted on Thermoelectric module (1) and breaker adaptor top (4a). Breaker adaptor top (4a) is inserted in the jaw assembly (5) which finally goes in cradle terminal top (6a).

Figure 2 , figure 3 and Figure 4 shows the back view, left view and isometric view of the single phase current path assembly respectively. These views show a Thermoelectric module (1) attached to heat sink (2) having fins (2a). Thermoelectric module is attached with the help of screws (3). Thermoelectric module has two sides (1a) the hot side and (1b) being cold. Figure. 5 shows the Peltier chip and its two sides. Power supply is given to peltier through wires (1c) and (1d).

Normally the electric supply is given to circuit breaker through cradle terminal top (6a). The current flows from cradle terminal top (6a) to cradle terminal bottom (6b) or can be vice versa. As long as the breaker is open there is no contact between Breaker terminal top (8a) and fingers (9).

In the suggested cooling technique, when the electric supply is given to the circuit breaker through the cradle terminal adaptor (7a) the current flows through the whole current path (excluding Thermoelectric module and heat sink assembly as it is not made up of electrically conductive material). As the time passes temperature starts increasing. Permissible increase in temperature is limited only up to 80⁰C above ambient temperature as this increase in temperature can further affect the performance of breaker increasing watt loss. Also it is not desirable as far as safety issue of customer is concerned. In order to decrease the temperature of the breaker we introduce a cooling chip (Thermoelectric module) (1) attached to breaker adaptor top (4a).

This Thermoelectric module works on the principle of 'Peltier Effect' which says that the heat will either be absorbed or radiated at the junction of two dissimilar metal when current is passed through them. One surface of Thermoelectric module or Peltier element (1) is cold (1a) while the other is hot (1b).The side which should be hot or cold is decided by direction of current flow. So, direction of current is made such that the cold side (1a) is always in direct contact with the breaker adaptor top (4a) while the hot side (1b) is connected to heat sink (2) for better dissipation of heat. Fins (2a) are arranged such that maximum air should flow through the gap between the fins. DC source is connected to Thermoelectric module (Peltier element) through wires (1c and 1d) which powers the Thermoelectric module.

When the DC supply is turned ON and current starts flowing in the desired direction and the Thermoelectric module starts operating in order to reduce the temperature of the circuit breaker. Heat will further flows to the heat sink for its dissipation in air. Thus, the side which is in touch with the heat sink becomes hot while the other become cold. The size, shape, fin type of the heat sink can be varied depending on the amount of power to be pumped out. As a result by the use of thermoelectric module (1) with the Heat sink (2) shown in present invention the overall watt loss of the circuit breaker reduces.

.

WE CLAIM:

1. An improved arrangement for cooling and watt loss reduction of multiple phase electrical switchgear , said arrangement comprising :
a circuit breaker assembly , said assembly comprising :
atleast one front facia means(15) adapted to display information of various parameters, ON/OFF conditions ;
atleast one side facia means (14) placed substantially on one of the side of said front facia means;
atleast one front housing (13) connected with said side facia means ;
atleast one rear housing (12) connected with said front facia means;
atleast one arc chute (11) connected with said front housing and rear housing ;
atleast one first breaker adaptor (4a) substantially placed on the top and connected with said rear housing
atleast one second breaker adaptor (4b) substantially placed on the bottom and connected with said rear housing ;
atleast one first breaker terminal (8a) substantially placed on the top and connected with said first breaker adaptor and
atleast one second breaker terminal (8b) substantially placed on the bottom and connected with said second breaker adaptor ;
a cradle means of said circuit breaker assembly operatively connected with said circuit breaker, said cradle means comprising :
atleast one jaw means comprising
a top jaw means (5) inserted into said first breaker adaptor of a circuit breaker assembly and
a bottom jaw means (5) inserted into said second breaker adaptor of a circuit breaker assembly;
atleast one first cradle terminal means (6a) placed substantially on the top and operatively connected with said top jaw means ;
atleast one second cradle terminal means (6b) placed substantially on the bottom and operatively connected with said bottom jaw means ;
atleast one first cradle terminal adapter means (7a) placed substantially on the top and operatively connected with said first cradle terminal means;
atleast one second cradle terminal adapter means (7b) placed substantially on the bottom and operatively connected with said second cradle terminal means;

wherein a thermoelectric module (1) is mounted top of said first breaker adaptor (4a) of a circuit breaker assembly , said module comprising :
a heat sink (2) mounted on said thermoelectric module(1) , said sink comprising plurality of fins (2a) ;
plurality screw (3) fixing said heat sink with said thermoelectric module;
atleast one wire means (1c,1d) connected with said module adapted to supply power to said module;
wherein said module further comprising a first side (1a) and a second side (1b) ;
wherein the direction of the current flow is such that said first side is directly connected with first breaker adaptor and said second side is connected to said heat sink .
wherein said first side differs in temperature from said second side.
2. Arrangement as claimed in claim 1 wherein said front housing is made of insulating medium/material.
3. Arrangement as claimed in claim 1 wherein said rear housing is made of insulating medium/material.
4. Arrangement as claimed in claim 1 wherein said plurality of fin is arranged so that maximum air flows through the gap between the fins.
5. Arrangement as claimed in claim 1 wherein said first side is cold adapted to absorb heat.
6. Arrangement as claimed in claim 1 wherein said second side is hot adapted to remove heat.
7. Arrangement as claimed in claim 1 wherein said thermoelectric module is made of non-conductive material.
8. Arrangement as claimed in claim 1 wherein said heat sink is made of non-conductive material.
9. Arrangement as claimed in claim 1 wherein comprising of thermoelectric couples.
10. Arrangement as claimed in claim 1 wherein further comprising plurality of fingers (9) connected with said first breaker terminal.
11. Arrangement as claimed in claim 1 wherein further comprising plurality of braids connected with said second breaker terminal adapted to assist the movement of main contact during breaking and making operations/ON/OFF operations.
12. Arrangement as claimed in claim 1 wherein said plurality of screws comprises a pair of screws.
13. Arrangement as claimed in claim 1 wherein said thermoelectric module comprises Thermoelectric couples.
14. Arrangement as claimed in claim 13 wherein said thermoelectric couples comprises (Joints) of a different type (P type and N type) doped thermoelectric material .
15. Arrangement as claimed in claim 14 wherein said thermoelectric material comprises Bismuth telluride.
16. An improved arrangement for cooling and watt loss reduction of electrical switchgear as herein substantially described and illustrated with the accompanying drawings.