FORM 2
THE PATENT ACT 1970
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)
1. TITLE OF THE INVENTION:
"A Cooling Fan Assembly for PCC Feeder Type Switchboard"
2. APPLICANT:
(a) NAME: Larsen & Toubro Limited
(b) NATIONALITY: Indian Company registered under the
provisions of the Companies Act-1956.
(c) ADDRESS: LARSEN & TOUBRO 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.

A Cooling Fan Assembly for PCC Feeder Type Switchboard
Field of invention
The present invention relates to Power Control Center (PCC, hereinafter) feeder type switchboards and more particularly to a cooling system of a PCC feeder type switchboard.
Background of the invention
PCC feeder type switch boards normally distribute electricity through a number of outgoing feeders wherein all the distribution links have an indoor installation to be securely contained within the switchboard panels. Usually, the temperature rise of these panels needs to be kept less than 70 °C for preventing damage to other electronic equipments and to prevent loss to property and lives. However, the distribution links contained within the switchboard panels naturally get heated up due to conduction of current thereby increasing temperature within the panels. Also, the breaker terminals form an ultimate source of heat generation as the moving contacts of these circuit breakers have resistance that is enormous. This additionally causes a lot of heat to be evolved that also transfers to the other links through conduction.
Accordingly, there are attempts are seen in the art wherein the cross-section of the current carrying conductors is increased to keep the temperature within the desired limit. However, in certain cases, especially for higher current ratings more than 5000A, the cross section of the current carrying conductors cannot be varied due limited predefined space of the panels, supporting links and the like.

Alternatively, the use of fans for controlling the temperature is preferred where increase in the cross section of the current carrying conductors is not possible. A well-known means of forced ventilation is generally adapted to reduce the temperature rise, wherein the fans are placed on the switchboard panels. These fans suck cool air from the external ambient thereby pushing out the heat air from the panels. These fans are usually placed on the external structural components of the panels, such as a door or a top panel, for removing the heat from the panels. However, these fans fail to reduce the temperature rise at the electrical terminals thereby providing incompetent cooling.
Moreover, maintenance of these fans is a hectic task as these fans are generally fixedly positioned in a stationary position along the switchboard panels. In case of failure of these fans, replacement of these fans in a live condition of the switchboard may expose user's life at a greater risk. Instead, switching off the breaker for preventing user's life from the risk may cause a huge loss in revenue since most of the switchboard panels have high rated current carrying incomers that may cause shutdown of the entire production line.
Accordingly, there exists a need of a cooling system that overcomes all the above mentioned drawbacks of the prior art.
Object of the invention
An object of the present invention is to provide a cooling fan assembly that substantially reduces a temperature rise of electrical terminals of a PCC feeder type switch board there by providing an instantaneous cooling effect.

Another object of the present invention is to provide a cooling fan assembly that is movable for facilitating positioning and removal of the cooling fans to or from a PCC feeder type switch board in a working condition of the PCC feeder type switch board.
Summary of the invention
The present invention provides a cooling fan assembly for reducing temperature rise of a PCC feeder type switch board. The cooling fan assembly comprises at least an opposed pair of fixed channels respectively connecting to an opposed pair of switchboard panels. Each of the fixed channels is having a front end that includes a threaded stopper welded thereto. The cooling fan assembly comprises at least an opposed pair of moving channels connecting to the opposed pair of fixed channels through a screw arrangement. The moving channel includes a primary flange and a plurality of secondary flanges defined thereon. The moving channels slidably move over the fixed channels. The secondary flanges assist in slidable movement of the movable channels in addition to preventing tilting thereof. The cooling fan assembly comprises a plurality of widthwise channels that is permanently connecting to the moving channels thereacross. The cooling fan assembly comprises a plurality of cooling fan units positioning over at least a couple of widthwise channels. The cooling fan unit includes an opposed pair of rotor retainers enclosing a rotor therein. The cooling fan unit includes a dome shaped structure that is having the rotor and the rotor retainers mounted thereon. The cooling fan unit includes a base plate that is connecting to the widthwise channels. The cooling fan units slidably move per the movement of the moving channels preferably in a forward direction or a rearward direction.

Brief description of the drawings
FIG. 1 is top perspective view of a cooling fan assembly constructed in accordance with the present invention;
FIG. 2 is a perspective view of a fan unit of the cooling fan assembly of FIG. 1;
FIG. 3 is a perspective view of a mounting frame unit of the cooling fan assembly of FIG. 1;
FIG. 4 is a side perspective view of a fixed channel of the mounting frame unit of FIG. 3;
FIG. 5 is a perspective view of a moving channel of the mounting frame unit of FIG.
3;
FIG. 6 illustrates an assembly of the moving channel and the fixed channel of the mounting frame unit of FIG. 3; and
FIG. 7 shows the cooling fan assembly of FIG. 1 in operation.
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.

Accordingly, the present invention provides a cooling fan assembly that includes a plurality of cooling fan units positioned on a mounting frame unit to slidably move the cooling fan units to or from a PCC feeder type switch board.
Referring to FIG. 1, a cooling fan assembly 10 mainly includes a plurality of cooling fan units 12 and a mounting channel unit 14. The cooling fan assembly 10 is adapted to be positioned within PCC feeder type of switch board panels (not shown) in this one preferred embodiment. However, it is understood that the cooling fan assembly 10 may be designed to be comfortably positioned within other types of switchboard panels in other alternative embodiments of the present invention. The mounting channel unit 14 assists in slidable positioning of the cooling fan assembly 10 to/from the switchboard panels. The cooling fan unit 12 includes three numbers of fans in this one particular embodiment, however, it is understood that the number of cooling fans may vary per desired cooling effect and dimensions of the switchboard panels in other alternative embodiments of the cooling fan assembly 10.
Referring to FIG. 2, the cooling fan unit 12 includes a rotor 16 that is securely held within an opposed pair of rotor retainers 18 to provide safety to a user. The rotor 16 and the rotor retainers 18 are mounted on a dome shaped structure 20 that is supported on a base plate 22. The base plate 22 includes a plurality of through holes 24 that assists in mounting of the cooling fan unit 12 on the mounting channel units 14. The cooling fan units 12 are connected to a power supply (not shown) by means of a plurality of cables (not shown) in which a fuse (not shown) is connected in series .The cables are terminated to a male three pin socket (not shown) which is adapted to be inserted into a female three pin socket (not shown). The female three pin socket (not shown) is preferably mounted on a front side of the switchboard panels. The female socket receives a supply from an Aux bus. The rotor 16 of the

cooling fan unit 12 is connected with a micro switch (not shown). The micro switch is configured to remain in an ON position during normal operation of the cooling fan unit 12. The micro switch is configured to attain an OFF position when the rotation of the rotor 16 stops during its operation. The micro switch is configured to actuate an alarm signal to the user in the OFF position.
Referring to FIG. 3, the mounting channel unit 14 includes an opposed pair of fixed channels 26, an opposed pair of movable channels 28 and a plurality of width wise channels 30. The fixed channels 26 are adapted to be mounted on the panels of the PCC feeder type of switch board. The movable channels 28 are configured to be positioned on the fixed channels 26. The widthwise channels 30 are configured to be permanently connected to the moving channels 28.
Referring to FIG. 4, each of the fixed channels 26 is adapted to be fixed on the switch board panels, preferably at a position immediately below the electrical terminals of the circuit breaker. Each of the fixed channels 26 is having a front end that includes a threaded stopper 32. The threaded stopper 32 is welded to the front end of the fixed channel 26 in this one preferred embodiment. The fixed channel 26 includes a plurality of holes 34 that facilitate engagement of the fixed channel 26 on the switchboard panel.
Referring to FIGS. 5-6, each of the moving channels 28 is adapted to slide over the respective fixed channel 26. Each of the moving channels 28 is having a front end that includes a primary flange 36. The primary flange 36 is adapted rest over the threaded stopper 32 of the fixed channel 26. The primary flange 36 ensures that the cooling fan unit 12 is positioned immediately below the breaker terminal without changing the orientation thereby ensuring efficiency of the system 10.

The moving channel 28 includes a plurality of secondary flanges 38 extending laterally from the surface of the moving channel 28. The secondary flanges 38 are L-shaped brackets in this one particular embodiment that slide over the fixed channels 26 aiding as a guide for the moving channel 28 in a forward and rearward directions respectively. This also prevents the moving channel 28 from being tilted in an upward direction when the module is pressed in a downward direction while removing out the cooling fan unit 12 thereby preventing the user to get in contact with the live terminals. The secondary flanges 38 also assist in connecting the widthwise channels 30 to the moving channels 28. However, it is understood here that the moving channels 28 are preferably welded to the fixed channels 26 in this one preferred embodiment.
The moving channel 28 is fixed to the fixed channel 26 by means of a screw arrangement 40. The screw arrangement 40 prevents disorientation of the moving channels 28 during transportation of the switchboard. The screw arrangement 40 also prevents change in the orientation of the cooling fan unit 12.
Referring to FIG. 7, the cooling fan assembly 10 is shown in operation. The widthwise channels 30 are such that two of the widthwise channels 30 facilitate mounting of the cooling fan units 12. The widthwise channels 30 are such that one of the widthwise channels 30 acts as a handle to move the moving channels 28 along the fixed channels 26 respectively in a forward direction or a rearward direction, as indicated by arrows A and B in this one embodiment. In operation, a spare cooling fan unit 12 (not shown) is arranged below the main cooling fan assembly 12 that is in use. The spare cooling fan units 12 are completely isolated from the main supply. In operation, the main cooling fan units 12 raise an alarm signal during failure that allows the user to identify the issue and take up online maintenance steps in a sequence as follows. In a first step, the cooling fan units 12

are electrically isolated from the supply by the removal of a plurality of male-female pin arrangements (not shown). In a second step, the screws 40 connecting the moving channels 28 to the stationary channels 26 are removed. In a next step, the cooling fan units 12 are removed by completely pulling them out of the switchboard panels in the direction indicated by the arrow-A- In a next step, the spare cooling fan unit 12 positioned immediately below the main cooling fan unit 12 is removed out in the direction indicated by the arrow-A. In a next step, the main cooling fan units 12 are replaced by the spare cooling fan units 12. In a further step, the screws 40 are fixed and the replaced cooling fan units 12 are electrically connected through the male- female pin arrangement. In a last step, the replaced cooling fan units 12 are positioned below the electrical terminals by completely inserting them inside the switchboard panels in the direction indicated by the arrow-B. It is understood here that, the fixed channels 26, the moving channels 28 and the L shaped brackets 38 assists in slidable movement of the cooling fan units 12 in the forward and rearward directions.
Advantages of the present invention
1. The cooling fan assembly 10 positions the cooling fan units 12 exactly below the electrical terminals that advantageously reduces the temperature of the electrical terminals by at least 20 C.
2. The cooling fan assembly 10 reduces the entire ambient temperature inside the switchboard panels in a more effective manner by reducing the temperature rise of the links associated with the terminals in the switchboard panels.
3. The cooling fan assembly 10 reduces the temperature rise at the moving contacts of the circuit breaker that cools the terminals of the breaker and

reduces heat generated at the moving contacts, which advantageously increases the performance of the cooling fan units 12 thereby reducing maintenance events.
4. The cooling fan assembly 10 totally prevents the user from coming into physical contact of the terminals within the switchboard panels thereby adding safety in operation.
5. The cooling fan assembly 10 facilitates easy removal and insertion of the cooling fan units 12 to/from the switchboard panels that advantageously simplifies maintenance time.
6. The cooling fan assembly 10 is cost effective. The cooling fan assembly 10 facilitates removal and replacement of the cooling fan units 12 in the live condition of the electrical terminals without the need of switching off the breaker which advantageously eliminates the need of shutting down the entire production line.
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 cooling fan assembly for reducing temperature rise of a PCC feeder type
switch board, the cooling fan assembly comprising:
at least an opposed pair of fixed channels respectively connecting to an opposed pair of switchboard panels, the fixed channels having a front end including a threaded stopper welded thereto;
at least an opposed pair of moving channels connecting to the opposed pair of fixed channels through a screw arrangement, the moving channel having a primary flange and a plurality of secondary flanges defined thereon, the moving channels slidably moving over the fixed channels, the secondary flanges assisting in slidable movement of the movable channels in addition to preventing tilting thereof;
a plurality of widthwise channels permanently connecting to the moving channels thereacross; and
a plurality of cooling fan units positioning over at least a couple of widthwise channels, the cooling fan unit having an opposed pair of rotor retainers enclosing a rotor therein, the cooling fan unit including a dome shaped structure, the dome shaped structure having the rotor and the rotor retainers mounted thereon, the cooling fan unit having a base plate connecting to the widthwise channels, the cooling fan units slidably moving per the movement of the moving channels respectively in a forward direction or a rearward direction.
2. The cooling fan assembly as claimed in claim 1, wherein the primary flange and the screw arrangement mutually prevent disorientation of the moving channels.
3. The cooling fan assembly as claimed in claim 1, wherein the temperature rise of the electrical terminals reduces by at least 20 C.

4. The cooling fan assembly as claimed in claim 1, wherein the moving channels position the cooling fan units directly below the electrical terminals to reduce the temperature rise.
5. The cooling fan assembly as claimed in claim 1, wherein the secondary flange is an L-shaped bracket.
6. The cooling fan assembly as claimed in claim 1, wherein at least one of the widthwise channels acts as a handle that assists in the movement of the moving channels.