US3595073A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Methods and arrangements for testing induction motors
Assignee: Individual
•
Filing: 1968-04-16
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Granted: 1971-07-27
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Expires: 1988-04-16
Abstract
Abstract Method apparatus Apparatus for testing induction machines by the back-to-back technique. The shafts of the motors are coupled together such that they will turn in the same direction through a motor or motor and gearbox combination. The motor or motor and gearbox combination enables the torques in the shafts of the motors being tested to be balanced.
Inventors
- 👤 David Gwilym Orwel Morris
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 12:18
CPC Classifications
G; G01; G01R; G01R31/00; G01R31/34
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
182 words
A method of testing an induction machine using a power source of lower power rating than the machine to be tested, comprising the steps of coupling the rotor of the induction machine to be tested through a mechanical coupling means to the rotor of a similar induction machine or of a synchronous machine, connecting the stators electrically, providing meters between the stators and an electrical power source to measure the joint stator electrical power input, operating the two machines with different and measured rotor speeds as motor and generator in a joint test to produce loading economically on the circulating power principle, rotating the rotors in the same sense with their torques opposed and with the system balanced, measuring the machine speeds and said torques to determine the joint rotor mechanical power input independently of the power losses in the mechanical coupling means, adding the joint stator electrical power input to the joint rotor mechanical power input to determine the joint power loss in the two machines, and allocating a portion of the joint power loss to the induction machine being tested.
Claim 2
Independent Claim
182 words
A method of testing an induction machine using a power source of lower power rating than the machine to be tested, comprising the steps of coupling the rotor of the induction machine to be tested through a mechanical coupling means to the rotor of a similar induction machine or of a synchronous machine, connecting the stators electrically, providing meters between the stators and an electrical power source to measure the joint stator electrical power input, operating the two machines with different and measured rotor speeds as motor and generator in a joint test to produce loading economically on the circulating power principle, rotating the rotors in the same sense with their torques opposed and with the system balanced, measuring the machine speeds and said torques to determine the joint rotor mechanical power input independently of the power losses in the mechanical coupling means, adding the joint stator electrical power input to the joint rotor mechanical power input to determine the joint power loss in the two machines, and allocating a portion of the joint power loss to the induction machine being tested.
Claim 3
Dependent Claim
32 words
A method as claimed in claim 1, wherein the two machines are run with opposing torques arranged to be equal in magnitude, the common torque therebetween being measured by a torque transducer.
Claim 4
Dependent Claim
49 words
A method as claimed in claim 1, wherein the two machines are run with opposing torques approximately equal in magnitude, and wherein torque equality is achieved in the presence of auxiliary dynamometric means, supplying a supplementary bias torque to the mechanically coupled rotor system by the auxiliary dynamometric means.
Claim 5
Dependent Claim
56 words
A method as claimed in claim 1, wherein in order to enable the difference in the losses of two different induction machines to be evaluated, each of them is run in turn against the same similar induction machine or synchronous machine, which is held in exactly the same electrical and mechanical condition in the two tests.
Claim 6
Dependent Claim
48 words
A method as claimed in claim 1, wherein the difference in the losses of an induction machine when operated first as a motor and then with equal but opposite torque as a generator is approximately determined by running it in successive circulating power tests against a synchronous machine.
Claim 7
Dependent Claim
147 words
Apparatus for testing an induction machine, comprising an induction machine or synchronous machine similar to the machine to be tested, mechanical coupling means for connecting the rotor shaft of the machine to be tested to the rotor shaft of said similar machine so that the machine torques are opposed, the coupling means being constructed to enable the said shafts to rotate in the same sense with accurately measurable different speeds and with the system in balance, electrical connections for connecting the stators of the two machines, first meters for measuring the joint stator electrical power input, second meters for measuring the electrical power of either one of the machines, means for connecting the two machines to an electrical power source through said first and second meters, and main torque transducer means for measuring the magnitude of one of the machine torques when the system is in balance.
Claim 8
Dependent Claim
147 words
Apparatus for testing an induction machine, comprising an induction machine or synchronous machine similar to the machine to be tested, mechanical coupling means for connecting the rotor shaft of the machine to be tested to the rotor shaft of said similar machine so that the machine torques are opposed, the coupling means being constructed to enable the said shafts to rotate in the same sense with accurately measurable different speeds and with the system in balance, electrical connections for connecting the stators of the two machines, first meters for measuring the joint stator electrical power input, second meters for measuring the electrical power of either one of the machines, means for connecting the two machines to an electrical power source through said first and second meters, and main torque transducer means for measuring the magnitude of one of the machine torques when the system is in balance.
Claim 9
Dependent Claim
43 words
Apparatus as claimed in claim 6 wherein auxiliary dynamometric-means are provided for applying a known bias torque to the mechanically coupled rotor system in such a way that the sum of the bias torque and the machine torques can be adjusted to zero.
Claim 10
Dependent Claim
45 words
Apparatus as claimed in claim 6 wherein the housing member of an auxiliary motor is coupled to the shaft of the machine to be tested, and the shaft of the core member of the motor is coupled to the shaft of the said similar machine.
Claim 11
Dependent Claim
37 words
Apparatus as claimed in claim 8, wherein the auxiliary motor shaft is coupled to said similar machine shaft through a gearbox, the gearbox housing being fastened to and free to rotate with the housing of the motor.
Claim 12
Dependent Claim
71 words
Apparatus as claimed in claim 9 wherein sliprings are provided on or adjacent to the auxiliary motor housing for electrical connections to the main torque transducer and the motor, brushes for the sliprings being carried in a brush-housing mounted on bearings on the shaft, and wherein means are provided for restraining rotation of the brush-housing and thus measuring the torque imposed by the brush assembly on the mechanically coupled rotor system.
Claim 13
Dependent Claim
53 words
Apparatus as claimed in claim 6, wherein the mechanical coupling means includes a close-ratio gearbox and an auxiliary balancing motor arranged to apply torque between a housing of the gearbox and one of the shafts thereof, the auxiliary balancing motor serving to hold said housing stationary and to provide the only constraint thereon.
Claim 14
Dependent Claim
31 words
Apparatus as claimed in claim 11, wherein auxiliary dynamometric-means are provided for applying a known bias torque between a fixed structure and a rotating member of the mechanically coupled rotor system.
Claim 15
Dependent Claim
25 words
Apparatus as claimed in claim 11, wherein auxiliary dynamometric-means are provided for applying a known bias torque between a fixed structure and the gearbox housing.
Claim 16
Dependent Claim
121 words
Apparatus as claimed in claim 6, wherein the mechanical coupling means includes a double-input gearbox having a housing which is free from rotational constraint by any fixed structure external to the housing, the gearbox having main shafts which are coaxial and arranged to rotate in the same sense when an auxiliary shaft means of the gearbox is stationary, the speed difference between the main shafts being adjustable by rotation of said auxiliary shaft means, said auxiliary shaft means being coupled to the rotor of an auxiliary motor the stator of which is carried on the housing, and an auxiliary balancing motor acting between the housing and one of the shafts of said machines serving to balance the torque on the housing.
Claim 17
Dependent Claim
31 words
Apparatus as claimed in claim 14, wherein auxiliary dynamometric-means are provided for applying a known bias torque between a fixed structure and a rotating member in the mechanically coupled rotor system.
Claim 18
Dependent Claim
24 words
Apparatus as claimed in claim 14, wherein auxiliary dynamometric-means are provided for applying a known bias torque between a fixed structure and said housing.
Claim 19
Dependent Claim
16 words
Apparatus as claimed in claim 16, wherein the mechanical-coupling means are supported on the auxiliary dynamometric-means.
Claim 20
Dependent Claim
13 words
Apparatus as claimed in claim 14, wherein the mechanical-coupling-means are supported on bearings.
Claim 21
Dependent Claim
17 words
Apparatus as claimed in claim 14, wherein the mechanical-coupling means are supported on a concentrically rotatable platform.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-07-26 | 1975-01-25 | 1975-07-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-07-26 | 1979-01-25 | 1979-07-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-07-26 | 1983-01-25 | 1983-07-27 | $7700.00 | Window Closed / Lapsed |