FIELD OF INVENTION
The invention generally relates to a high current switchgear in house development. In particular the invention relates to a modified switchgear in which the size is compact and provides efficient means of cooling.
BACKGROUND OF THE INVENTION
With the rising normal currents in switchgear especially in context of arc resistant switchgear, wherein air flow and vents for providing ample air flow is a critical issue to address, maintaining the maximum rise in temperature of current carrying conductors is a critical issue.
Natural convection cooling methods, though efficient, have their own limited capabilities. For normal currents, there is a threshold air flow rate that is difficult to maintain through normal convection. In such cases forced cooling provides a better opportunity.
Patent DE8915141U1 1990-03-22 (fig 1) discusses one such utilization of forced cooling methods wherein air is pushed inside the chamber through a fan employed below the withdrawable cubicle.
Here, the cooling conduit is marked by (25) (refer Fig 1). Air passed through port (25), passes through conduit (23) and enters the current carrying conductors’ chamber at (28) and (29). The air, after collecting heat from current carrying conductors (39), escapes through (32). Additionally, fans can be employed in the space (23) in Fig 1 to provide forced cooling. However, this invention has a limited advantage as cooling on other current carrying terminals (3) and (2), is not ensured.

This will limit the cooling to current carrying conductors in a particular area only.
German patent Number DE617231A1 1987-11-26 “Encapsulated electrical switch panel” (refer Fig 2) discusses a better approach to limit the rise of temperature in current carrying conductors in all the three chambers marked as (2), (7) and (8) in Fig 2.
This invention employs forced cooling of suction type wherein an artificial draught is created by means of fan employed at (25). This results in suction and evacuation of warm air from current carrying conductors in chamber (2). Also this invention also provides cooling of current carrying conductors in chamber (7) and (8) through a conduit (20) and a ventilation flap of air at (22). However, since ventilation flap is at (22), it poses a risk to the user because in case of an arc fault, the smoke and arc can escape through door (22) and hit the user/ personnel.
To alleviate the drawbacks of the prior art the present invention teaches about a switchgear where cooling of current carrying conductors is taken care of in all chambers of switchgear panel. Suction or exhaust of air is on any of the three sides critical to the safety of personnel, i.e. front, lateral or rear.
In the prior art temperature rise it was observed that the contacts near pole head and jaw finger contacts gets deteriorated at such a high current due to which failure occurs. The connection for each phase is done with a special arrangement of pole head developed for conduction of high current. In the prior art the pole head was a Copper of

approximately 24 Kg per breaker which is replaced with an Alluminium Pole head resulted in huge reduction in costing.
In the prior art, the panel size was 2460 X 2605 X 1835 mm in which three compartments were used each of 820 mm width. The central compartment was used for mounting the Truck in which the breaker mechanism is mounted. Other two compartments at both ends are blank panels available for normal cooling and providing gap between other panels.
OBJECTS OF THE INVENTION
An object of the invention is to provide a unique design of panel for high current switchgear.
Another object of the invention is to optimize the overall dimensions of panel.
Another object of the invention is to provide a cooling assembly to ensure safety to personnel at faulty condition.
Yet another object of the present invention to reduce the temperature rise at contacts.
BREIF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
Fig 1 shows a cooling chamber of a switch gear as in prior art. Fig 2 shows a cooling chamber at faulty condition as in prior art. Fig 3 shows cooling chamber of a switch gear as in prior art. Fig 2 shows a cooling chamber at faulty condition as in prior art. Fig 5 shows a cooling chamber in accordance to the invention.

Fig 6 shows schematic diagram of a cooling chamber in accordance to the invention.
DETAILED DESCRIPTION OF DRAWINGS:
A panel is to be designed to integrate the AIS for high current rating of
3500A. The invention relates to a three phase common Panel type AIS
switchgear, particularly subjected to high current of 3500A.
Conventionally, a set of panel were supplied of 2460mm as the total width and 2605mm as total depth with a height of 1835mm, leading to requirement of more space in switchgear control room.
In order to make the AIS suitable for 3500A it has been designed with forced cooling. The floor area occupation is reduced by 50%.
The invention is described with the help of Figures 5 and 6, where the switchgear assembly comprises of three vertically segregated modules (47, 48 and 49). Module 49 houses the three chambers, namely, breaker chamber (6), busbar chamber (29), and cable chamber (28). Modules 47 and 48 serve as Air Columns for Module 49.
Instrument chamber (3), used for mounting various measuring instruments and physically separated from any of the other chamber rests on top of breaker chamber (6). Instrument chamber (3) is accessible by a latched door (4).
Breaker chamber (6) is accessible by a latched door (5). Cable chamber (28) is accessible by top cover (40) and bottom cover (41).

To collect the exhaust gases, in occurrence of an arc fault in the switchgear assembly, exhaust plenum (39) is provided on top, so that exhaust gases from breaker chamber (6), busbar chamber (29), and cable chamber (28) can collect in the common area.
Breaker chamber (6) houses a moving truck (7) that can be moved in and out of the breaker chamber (6). Truck (7) consists of insulating items (8 and 9), conducting poles (10 and 11), vacuum interrupter bottle (36) and conductors (13 and 14). Truck (7) can be moved with the help of wheels (12) on the bottom of the truck frame. Breaker Chamber (6) houses a heater to remove any moisture traces (17B). Breaker Chamber (6) houses top covers 18’ (right cover), 18” (left cover) and 18 (central cover) that can exchange and communicate air between breaker chamber (6) and exhaust plenum (39).
Busbar Chamber (29) houses Conducting droppers (22) for R-Phase, (23) for Y-Phase and (24) for B-Phase. The conducting droppers (22, 23 and 24) are isolated from earth by insulating items (25, 26 and 27). Insulating items (16) forms a thermal and insulating interface between breaker chamber (6) and busbar chamber (29). Busbar Chamber (29) houses a heater to remove any moisture traces (17A). Busbar Chamber (29) houses top covers 19’ (right cover), 19” (left cover) and 19 and 20 (central cover) that can exchange and communicate air between busbar chamber (29) and exhaust plenum (39).
Cable chamber (28) houses Conducting items (43) that goes outside the panel and connects with the cables (44). The interface between the cable chamber (28) and ground opening (46) are sealed thermally and physically with sealant (45). Cable Chamber (28) houses a heater to remove any moisture traces (17C). Cable Chamber (28) houses top covers

21’ (right cover), 21” (left cover) and 21 (central cover) that can exchange and communicate air between cable chamber (28) and exhaust plenum (39). Cable chamber (28) is physically and thermally separated from busbar chamber (29) by interface (42) and from breaker chamber (6) by insulating item (15).
When Truck (7) is moved in, it makes connection between Conductors (14) and conducting droppers (22, 23 and 24). Simultaneously, Conductors (13) makes connection with conducting item (43).
For forced cooling, fans are employed in the switchgear assembly. Fans 31, 32, 34 and 35 are employed for cooling on the sides of breaker chamber (6). Fan 33 is employed for cooling at the bottom of Busbar chamber (29). Fan 36 is employed for cooling at the top of Cable chamber (28).
Switchgear assembly houses current carrying conductors and form a current loop. When the current loop is complete, the current typically flows from Conducting droppers (22, 23 and 24) to Conductor (14) to Pole (10) to Vacuum interrupter (36) to pole (11) to conductor (13) to conducting item (43) and then to the outgoing cable (44). Because of flow of higher current values, there is heating of conductors and subsequently, a rise in temperature is observed. This invention presents a unique method for cooling and arresting temperature rises in a switchgear panel.
The air columns (47 and 48) are utilized as source of cool air for effective cooling of conductors placed in Module 49. When fans (31,32,34,35) are switched on, they push the air towards the current loop items (10,14 and 11, 15) inside the breaker chamber (6).

The air (37, 38) the fans (31,32,34,35) push inside the breaker chamber (6) is pulled inside the air columns (47 and 48) through communicable interface (A,B) and (A’, B’). The air then falls onto current loop items (10,14 and 11, 15) inside the breaker chamber (6), thereby cooling them. Upon rising temperatures of the current loop items (10,14 and 11, 15), the surrounding air gets heated and escapes (through C) the breaker chamber through communicable top cover (18).
Along the same lines, when fan 33 is switched on, it push the air towards the current loop items (14, 22,23,24) inside the busbar chamber (29). The air (50) the fans (33) push inside the busbar chamber (29) is pulled inside the air columns (47 and 48) through communicable interface (A,B) and (A’, B’) along 50’ and 50”. The air then falls onto current loop items (14,22,23,24) inside the busbar chamber (29), thereby cooling them. Upon rising temperatures of the current loop items (14,22,23,24), the surrounding air gets heated and escapes (through D) the busbar chamber(29) through communicable top cover (19 and 20).
Along the same lines, when fan 36 is switched on, it push the air towards the current loop items (13, 43) inside the cable chamber (28). The air (50) the fans (36) push inside the cable chamber (28) is pulled inside the air columns (47 and 48) through communicable interface (A,B) and (A’, B’) along 50’ and 50”. The air then falls onto current loop items (13,43) inside the cable chamber (28), thereby cooling them. Upon rising temperatures of the current loop items (13,43), the surrounding air gets heated and escapes (through E) the cable chamber(28) through communicable top cover (21).

WE CLAIM;
1. A cooling assembly for a switchgear that comprises: three vertically
segregated modules (47, 48 and 49), wherein the module (49) houses a
break chamber (6), a bus bar chamber (29) and cable chamber (28) such
that the modules (47 and 48) act as air columns;
a set of plurality of cooling fans disposed within the said modules (47, 48 and 49) at predefined position;
characterized in that the plurality of fans are so arranged to push the air towards a plurality of current loop items within the circuit breaker (6) at faulty conditions; by means of a communicable interface thereby cooling the current loop items; and atleast a top communicable cover to allow passage of heated air.
2. A cooling assembly as claimed in claim 1, wherein plurality of cooling
fans (31, 32) are placed adjoining module (48) and module (49).
3. A cooling assembly as claimed in claim 1, wherein plurality of cooling fans (34, 35) are placed adjoining module (47) and module (49).
4. A cooling assembly as claimed in claim 1, wherein plurality of cooling fans (33, 36) are disposed within the module (49) at predefine positioned in an alignment.
5. A cooling assembly as claimed in claim 1, wherein as illustrated in the accompanying drawings.