Claims:We claim:

1. An air gap measuring device (100) for measuring air gap between rotor and stator in hydro generator/ motor, the measuring device (100) comprises:
a measuring strip female part (101) having a plurality of holes near each end with threads;
a measuring strip male part (102) having a plurality of holes near each end wherein the measuring strip male part (102) is connected with the measuring strip female part (101) through plate and screw arrangement;
characterized in that
inner surface of the measuring strip female part (101) is equal to rotor outer diameter (301) and outer surface of the measuring strip male part (102) is equal to the stator core inner diameter (302); and
the measuring strip female part (101) is firmly fixed with rotor outside diameter (301) and measuring strip male part (102) is firmly fixed with stator core inside diameter (302).
2. The air gap measuring device (100) as claimed in claim 1 wherein the air gap measuring device (100) is placed in the air gap region either at the top or at the bottom of the said hydro generator/ motor.
3. The air gap measuring device (100) as claimed in claim 1 wherein plate and screw arrangement comprises a joint plate (103) with plurality of holes and plurality of screws (104) on each joint plate (103).
4. The air gap measuring device (100) as claimed in claim 2 wherein plurality of holes provided on the joint plate (103) are of two types circular and elliptical.
5. The air gap measuring device (100) as claim in claim 1 wherein a hole with thread is provided at the center of the measuring strip female part (101) for fixing a lifting hook (105).

6. The air gap measuring device (100) as claimed in claim 1 wherein a feeler gauge (201) is inserted between the measuring strips (101 and 102).
7. The air gap measuring device (100) as claimed in claim 1 wherein air gap between the rotor and stator in hydro generator/ motor is measured by calculating aggregate of thickness of air gap measuring device (100) and thickness of feeler gauge (201).
, Description:
FIELD OF INVENTION:
[001] The present invention relates air gap measuring device. In particular, the present invention relates to an air gap measuring device for measurement of air gap between rotor and stator in hydro generators / motors without affecting the performance. This novel arrangement is simple, economical and enhances the accuracy of measurement of air gap.
BACKGROUND OF THE INVENTION:
[001] Air gap is ordinarily formed between rotor core (rotating part) and stator core (stationary part) of Generator or motor. The air gaps are practically unavoidable because of the relative movement of different parts. The air gap is to be maintained as per design of each generator/motor. The air gap is needed to separate the revolving rotor from the stator. The air gap should be as small as possible to reduce the magnetizing power requirement, yet large enough to prevent contact between the two despite manufacturing tolerances on their dimensions, or movement resulting from mechanical deflection and looseness in supporting bearings. Unbalance of the air gap may cause abnormal vibration and deterioration of the electrical characteristics of the generator/motor and shorting their life.
[002] The present subject matter provides an air gap measuring device and its arrangement in the hydro generators / motors without affecting the performance of the generators.
[003] The proposed air gap measuring device and the arrangement described in the present invention is:
1. Simple in construction and easy to use.
2. Does not require any external source of supply for measurement.
3. Does not require skilled manpower for measurement.
[004] The proposed air gap measuring device can also be effectively utilized in various generators / motors in standstill condition.
OBJECTS OF THE INVENTION:
[005] The principal object of the present invention is to provide an air gap measuring device to accurately measure air gap of generator / motor.
[006] Another object of the present invention is to provide an air gap measuring device which is simple in construction.
[007] Yet another object of the present invention is to provide an air gap measuring device which is easy to assemble, use and maintain.
[008] Still yet another object of the present invention is to propose an arrangement of the said air measuring device in the generator / motor.
[009] These and other objects and advantages of the present subject matter will be apparent to a person skilled in the art after consideration of the following detailed description taken into consideration with accompanying drawings in which preferred embodiments of the present subject matter are illustrated.
SUMMARY OF THE INVENTION:
[010] The present subject matter relates to an air gap measuring device and its arrangement in the generator/ motor. According to an embodiment of the present invention the air gap measuring device consist of a measuring strip female part and a measuring strip male part connected to each other through joint plate and screw arrangement. A lifting hook is provided for lifting the complete assembly.
[011] To measure the air gap the air gap measuring device is to be placed in the air gap region either at top or bottom of the generator as shown in figure 2, 3 and 4. Feeler gauge is inserted in between the measuring strip in such a way that each measuring strip is firmly in contact with inner diameter of stator core and rotor outside diameter as shown in figure 5. Hence the total value of air gap measured will be equal to the aggregate of thickness of air gap measuring device and thickness of filler gauge.
[012] To further understand the characteristics and technical contents of the present subject matter, a description relating thereto will be made with reference to the accompanying drawings. However, the drawings are illustrative only but not used to limit scope or the present subject matter.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
[013] It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered for limiting of its scope, for the invention may admit to other equally effective embodiments. Embodiment of the present subject matter are now described, by way of example, and with reference to the accompanying figures, in which:
[014] Figure 1 illustrate proposed air gap measuring device.
[015] Figure 2illustrate arrangement of air gap measuring device in generator/ motor.
[016] Figure 3 illustrate cross sectional view of air gap measuring device at high position in generator/ motor.
[017] Figure 4 illustrate cross sectional view of air gap measuring device at low position in generator/ motor.
[018] Figure 5 illustrate arrangement of generator/motor (top view, R) showing measurement of air gap by using proposed air gap measuring device.
[019] The figures depict embodiments of the present subject matter for the purposes of illustration only. A person skilled in the art will easily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles for the disclosure herein

DETAIL DESCRIPTION OF THE PROPOSED DESIGN WITH OBJECTS OF THE INVENTION:
[002] It should be appreciated by those skilled in the art that any block diagrams herein represent conceptual views of illustrative systems embodying the principles of the present subject matter. Similarly, it will be appreciated that any flow charts, flow diagrams, state transition diagrams, pseudo code, and the like represent various processes which may be substantially represented in computer readable medium and executed by a computer or processor, whether or not such computer or processor is explicitly shown.
[003] In the present disclosure, the word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any embodiment or implementation of the present subject matter described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.
[004] While the present disclosure is susceptible to various modifications and alternative forms, specific embodiment thereof has been shown by way of example in the drawings and will be described in detail below. It should be understood, however that it is not intended to limit the present disclosure to the particular forms disclosed, but on the contrary, the present disclosure is to cover all modifications, equivalents, and alternative falling within the spirit and the scope of the present disclosure.
[005] The terms “comprises”, “comprising”, or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a setup, device or method that comprises a list of components or steps does not include only those components or steps but may include other components or steps not expressly listed or inherent to such setup or device or method. In other words, one or more elements in a system or apparatus proceeded by “comprises… a” does not, without more constraints, preclude the existence of other elements or additional elements in the system or apparatus.
[006] In the following detailed description of the embodiments of the disclosure, reference is made to the accompanying drawings that form a part hereof, and in which are shown by way of illustration specific embodiments in which the disclosure may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosure, and it is to be understood that other embodiments may be utilized and that changes may be made without departing from the scope of the present disclosure. The following description is, therefore, not to be taken in a limiting sense.
[020] The present invention will be described in detail below with reference to an embodiment as shown in the drawing.
[021] As shown in Figure 1 the air gap measuring device comprises a measuring strip female part (101) and a measuring strip male part (102). Inner surface of the measuring strip female part (101) is equal to rotor outer diameter (301) and outer surface of the measuring strip male part (102) is equal to stator core inner diameter (302). A plurality of holes with threads are provided on each measuring strip female part (101) and measuring strip male part (102) to provide means for connecting the measuring strip female part (101) with measuring strip male part (102).
[022] The measuring strip female part (101) and a measuring strip male part (102) are connected to each other through a plate and screw arrangement provided at each end of the measuring part (101 and 102). The plate and screw arrangement comprise a joint plate (103) with a plurality of holes and plurality of screws (104) at each joint plate (103). The joint plate (103) comprises two types of holes one being circular in shape and other being elliptical in shape. The elliptical shape hole is provided to accommodate a feelers gauge. Another hole with thread is provided at the center of measuring strip female part (101).
[023] A lifting hook (105) is fixed by means of screw at the hole provided at the center of the measuring strip female part (101) for lifting the complete assembly for maintenance and other purposes.
[024] To measure the air gap by the proposed air gap measuring device, the air gap measuring device is placed in the air gap region either at the top or at the bottom as shown in figure 2, 3 and 4. The measuring strip female part (101) is fixed with rotor outside diameter and the measuring strip male part is fixed with stator core inside diameter. The feeler gauge is inserted in between the measuring strips in such a way that measuring strip female part (101) is firmly in contact with inner diameter of stator core and measuring strip male part (102) is firmly in contact with rotor outside diameter as shown in figure 5.
[025] The aggregate of thickness of air gap measuring device and thickness of filler gauge gives air gap between the rotor and stator in hydro generator / motor.

[026] The air gap measuring device and its arrangement proposed in the present invention, is developed for utilization in various projects.
The advantages of the proposed air gap measuring device are as follows:
1. The device is simple in construction and easy to use.
2. The device does not require any external source of supply for measurement.
3. The device does not require skilled manpower for measurement.
[027] It will be further appreciated that functions or structures of a plurality of components or steps may be combined into a single component or step, or the functions or structures of one-step or component may be split among plural steps or components. The present invention contemplates all of these combinations. Unless stated otherwise, dimensions and geometries of the various structures depicted herein are not intended to be restrictive of the invention, and other dimensions or geometries are possible. In addition, while a feature of the present invention may have been described in the context of only one of the illustrated embodiments, such feature may be combined with one or more other features of other embodiments, for any given application. It will also be appreciated from the above that the fabrication of the unique structures herein and the operation thereof also constitute methods in accordance with the present invention. The present invention also encompasses intermediate and end products resulting from the practice of the methods herein. The use of “comprising” or “including” also contemplates embodiments that “consist essentially of” or “consist of” the recited feature.
[028] Although embodiments for the present subject matter have been described in language specific to structural features, it is to be understood that the present subject matter is not necessarily limited to the specific features described. Rather, the specific features and methods are disclosed as embodiments for the present subject matter. Numerous modifications and adaptations of the system/component of the present invention will be apparent to those skilled in the art, and thus it is intended by the appended claims to cover all such modifications and adaptations which fall within the scope of the present subject matter.