FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
As amended by the Patents (Amendment) Act, 2005
&
The Patents Rules, 2003
As amended by the Patents (Amendment) Rules, 2006
COMPLETE SPECIFICATION
(See section 10 and rule 13)
TITLE OF THE INVENTION
A device for testing the temperature rise in a single bearing alternator


APPLICANTS
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli, Mumbai -Maharashtra, India, an Indian Company
INVENTORS
Bhujbal Eknath and Dabeer Vivek, both of Crompton Greaves Ltd, LT Motors Division (M3), A-6/2 MIDC, Ahmednagar 414001, Maharashtra, India, both Indian Nationals
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the nature of this invention and the manner in which it is to be performed:


FIELD OF THE INVENTION
This invention relates to a device for testing the temperature rise in a single bearing alternator
BACKGROUND OF THE INVENTION
A diesel generator set comprises an alternator or AC generator driven by a diesel engine. The alternator shaft is coupled to the fly wheel of the diesel engine and the end shield of the alternator is coupled to the engine housing, During operation of the diesel generator set, excitation current generated in the rotor winding of the alternator induce AC current and AC voltage in and across the stator winding of the alternator, respectively. Due to the currents flowing through the rotor and stator windings, the resistance of the windings increases and the windings get heated up. Excessive heat generation in the windings will damage the insulation of the windings and lead to premature failure of the alternator. The alternator is kept cooled by a suction fan mounted on the alternator shaft and disposed in the suction chamber comprising the alternator end shield and engine housing. During rotation of the alternator shaft with the engine shaft, the suction fan rotates within the suction chamber and creates suction within the suction chamber so as to suck in atmospheric air axially over the windings so as to cool the windings. Prior to assembling a single bearing alternator to a diesel engine and forming a diesel generator set, the temperature rise in the windings of the alternator is normally determined so as to know in advance the extent of temperature rise in the windings of the alternator at the rated speed of rotation of the alternator and prevent premature failure of the alternator in actual use. A generally used device for testing temperature rise in a single bearing alternator comprises a dummy housing formed of a ring which is L-shaped in crosssection and is rotatably mounted on a shaft disposed for rotation about a horizontal axis. The ring is

mounted on the shaft with the help of spaced apart radial ribs and is provided with bolt holes to facilitate coupling of the ring to the end shield of the alternator to be tested, with bolts. The inner portion of the shaft of the device is adapted to be connected to the alternator shaft and the outer portion of the shaft of the device is adapted to be connected to the shaft of a driving electric motor. During testing of the alternator, drive is given to the shaft of the device by operating the electric motor. The suction fan on the alternator shaft rotates with the alternator shaft and creates suction effect so as to axially draw atmospheric air over the windings of the alternator and keep the alternator cooled. However, due to the spacing between the radial ribs supporting the ring, the suction chamber comprising the ring and alternator end shield and the suction effect created by the suction fan within the suction chamber comprising the ring and the alternator end shield are not true to and matching with the actual suction chamber that would comprise the engine housing and alternator end shield and the actual suction effect that would have been created in the actual running condition of the alternator when the alternator is coupled with a diesel engine. As a result the temperature rise in the windings of the alternator during testing is not accurate and true to the temperature rise that would have occurred during the actual running condition of the alternator when coupled with the diese! engine. Therefore, the device does not help to accurately measure the temperature rise in the windings of the alternator during testing and is not reliable. Because of the incorrect measurement of temperature rise in the windings of the alternator during testing, the alternator windings may on actual use in the diesel generator set get excessively heated. As a result the insulation of the windings may get damaged and the alternator may fail prematurely.

OBJECTS OF THE INVENTION
An object of the invention is to provide a device for testing the temperature rise in a single bearing alternator, which device helps to make accurate measurement of the temperature rise in the windings of the alternator and which is reliable.
Another object of the invention is provide device for testing the temperature rise in a single bearing alternator, which device is simple in construction and is easy and convenient to operate.
DETAILED DESCRIPTION OF THE INVENTION
According to the invention there is provided device for testing the temperature rise in a single bearing alternator, the device for the testing temperature rise in a single bearing alternator, the device comprising a dummy housing including a dished member comprising a closed portion and an endless sidewall portion projecting from the closed portion and rotatably mounted on a shaft disposed for rotation about a horizontal axis, the sidewall portion of the dished member being adapted to be tight fitted to the end shield of the alternator to be tested, the inner portion of the shaft of the device being adapted to be coupled to the alternator shaft and the outer portion of the shaft of the device being adapted to be coupled to the shaft of a driving electric motor, the volume of the dished member corresponding to the volume of the diesel engine to be coupled to the alternator.

The following is a detailed description of the invention with reference to the accompanying drawings, in which:
Fig 1 and 2 are opposite side views of the device for testing the temperature rise in a single bearing alternator according to an embodiment of the invention; and
Fig 3 is a partly crosssectional view of the device of Figs 1 and 2.
The device 1 for testing the temperature rise in a single bearing alternator as illustrated in Figs I to 3 of the accompanying drawings comprises a dummy housing formed of a dished member 2 having a closed portion 3 and endless sidewall portion 4 projecting from the closed portion. The closed portion is formed with a hub 3a and the sidewall portion 4 is stepped construction (step marked 4a) and is provided with bolt holes 5. The closed portion is reinforced by radial ribs 6 provided externally across the outer surface thereof. The dished member is rotatably mounted on a shaft 7 disposed for rotation about a horizontal axis. The dished member is rotatably mounted on the shaft 7 using bearings 8 located between the shaft 7 and hub 3 a of the dished member. The inner portion of the shaft 7 is provided with engaging holes 9 and the outer portion of the shaft 7 is provided with a key 10. During testing of a single bearing alternator (not shown) for temperature rise in the windings thereof, the end shield of the alternator is tight fitted to the sidewall portion of the dished member with bolts (not shown) passing through the bolt holes in the sidewall portion and corresponding bolt holes in the end shield of the alternator. Engaging pins provided at the outer end of the alternator shaft are engaged in the engaging holes 9 at the inner portion of the shaft 7. The outer portion of the shaft 7 is coupled to the shaft (not shown) of a driving electric motor (not shown) by engaging the key 10 on the outer portion of the shaft 7 in a corresponding keyway in the electric motor

shaft. The volume of the close ended dished member corresponds to the housing (not shown) of the diesel engine (not shown) to be used for driving the alternator shaft during the actual use of the alternator. Therefore, the suction chamber comprising the end shield of the alternator and the dished member, matches with and corresponds to the suction chamber formed by the alternator end shield and diesel engine housing during actual use of the alternator. As a result, during testing the suction effect created by the suction fan mounted on the alternator shaft and disposed within the suction chamber comprising the end shield of the alternator and the dished member corresponds to and is true to the actual suction effect created by the suction fan during the actual use of the alternator in combination with the diesel engine. Therefore, the temperature rise in the windings of the alternator is accurately determined during testing and the device of the invention is reliable. According to the invention it is possible to accurately determine the temperature rise in the windings of the alternator during testing and it is possible to prevent damage to the insulation of the windings of the alternator and premature failure of the alternator during actual working thereof. Besides, the device of the invention is simple in construction and easy and convenient to operate. The device of the invention is made of a mechanically strong and durable material like steel.
Instead of providing bolt holes in the sidewall portion of the dished member, the sidewall portion of the dished member can be adapted to be fitted to the end shield of the alternator by other known means. Instead of providing engaging holes at the inner portion of the shaft of the device, the inner portion of the shaft of the device can be adapted to be coupled to the alternator shaft by other known means. The sidewall portion of the dished member need not be stepped construction. The radial ribs 6 are optional. Such variations of the invention are to be construed and understood to be obvious to those skilled in the art and within the scope of the invention.

We claim:
1. A device for testing the temperature rise in a single bearing alternator, the device comprising a dummy housing including a dished member comprising a closed portion and an endless sidewall portion projecting from the closed portion and rotatably mounted on a shaft disposed for rotation about a horizontal axis, the sidewall portion of the dished member being adapted to be tight fitted to the end shield of the alternator to be tested, the inner portion of the shaft of the device being adapted to be coupled to the alternator shaft and the outer portion of the shaft of the device being adapted to be coupled to the shaft of a driving electric motor, the volume of the dished member corresponding to the volume of the diesel engine to be coupled to the alternator.
2. The device as claimed in claim 1, wherein the sidewall portion of the dished member is stepped construction and is provided with bolt holes.
3. The device as claimed in claim 1 or 2, wherein the closed portion of the dished member is reinforced by radial ribs provided externally across the outer surface thereof.
4. The device as claimed in anyone of claims 1 to 3, wherein the dished member is formed with a hub which is rotatably mounted on the shaft of the device.
5. The device as claimed in any one of claims 1 to 4, which is made of steel.
Dated this 23rd day of December 2008.