WO2001081934A1 - Insulation tester for squirrel cage rotors - Google Patents
Insulation tester for squirrel cage rotors Download PDFInfo
- Publication number
- WO2001081934A1 WO2001081934A1 PCT/US2000/010549 US0010549W WO0181934A1 WO 2001081934 A1 WO2001081934 A1 WO 2001081934A1 US 0010549 W US0010549 W US 0010549W WO 0181934 A1 WO0181934 A1 WO 0181934A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- rotor
- measuring
- insulation
- quality
- squirrel cage
- Prior art date
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/34—Testing dynamo-electric machines
- G01R31/346—Testing of armature or field windings
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/34—Testing dynamo-electric machines
Definitions
- the field of the invention relates to electrical motors and more particularly to induction motors.
- Induction motors such as squirrel cage induction motors, are in common use. Such motors, because of their simplicity and reliability, are one of the most widely used electric motors in use today.
- a method and apparatus are provided for measuring a quality of insulation surrounding rotor bars of a rotor of a squirrel cage induction motor.
- the method includes the steps of applying an alternating magnetic flux to opposing ends of the rotor measuring a power level absorbed by the rotor as a result of the applied alternating magnetic flux.
- The. met od further includes the step of using the measured power level as a relative measure of the quality of the insulation of the rotor bars.
- the application of an alternating magnetic flux may be performed without complicated equipment or procedures.
- the relative power absorbed 5 by the rotor provides a reliable measure of the quality of the insulation of the rotor and, consequently, of the efficiency of its operation.
- the efficiency of a motor is an important factor in not only saving energy, but also in extending a service life of the motor by reducing internal heating.
- FIG. 1 depicts a block diagram of an insulation tester and tested rotor in accordance with an illustrated embodiment of the invention
- FIG. 2 depicts a side view of the electromagnet and rotor of the system of FIG. 1;
- FIG. 3 depicts a schematic circuit of circuits detected by the system of
- FIG. 1 A first figure.
- FIG. 4 depicts an alternate electromagnet arrangement and rotor of the system of FIG. 1;
- FIG. 5 depicts a side view of the electromagnetic arrangement and o rotor of FIG. 4;
- FIG. 6 depicts a schematic of circuits detected by the system of FIG. 1.
- FIG. 1 shows a rotor insulation tester 10, generally, in accordance with an illustrated embodiment of the invention. Included within the insulation tester 10 is an electromagnet 12 and insulation tester controller 14. Also shown in FIG. 1 is an end view of a rotor 16 of a squirrel cage " induction motor.
- rotor 16 of FIG, 1 Included within the rotor 16 of FIG, 1 are a number of teeth 18, 20, 22, 24 (four shown) which interact with a stator (not shown) to provide a flux path through the rotor 16.
- a number of rotor bars 26, 28, 30, 32 are also shown disposed between the teeth, skewed or parallel to a longitudinal axis of the rotor 16.
- Each rotor bar 26, 28, 30, 32 may be connected at opposing ends to a respective end ring 34, 44 (end ring 34 is shown schematically in FIG. 1).
- the rotor bars and end rings together form a series of shorted turns in which current is induced by operation of the stator. To ensure proper operation, the bars and end rings are insulated from the teeth and metallic flux paths lying underneath the bars and end rings.
- FIG. 2 is a side view of the rotor 16 and electromagnet 12 of FIG. 1. As shown, the electromagnet 12 is disposed against the rotor 16 with opposing poles of the electromagnet 12 disposed against opposing ends of a single tooth 24 of the rotor 16. It is to be understood that the poles of the electromagnet 12 could be disposed against any tooth 18, 20, 22, 24 of the rotor 16 for the testing of the insulation of adjacent rotor bars.
- FIG. 2 also shows a flux path FI that may be created within the rotor 16 (between opposing poles of the electromagnet 12) upon application of an alternating current to a winding 36 of electromagnet 12.
- the flux path FI enters through a tooth (in this case tooth 24) on one side of FIG. 2, proceeds longitudinal along the rotor 16, (perpendicularly to the rotor laminations) from a first end of the rotor 16 to a second end of the rotor 16 and again exits through the tooth.
- FIG. 3 shows a schematic representation of a pair of circuits 40, 42 that may be created within the rotor 16 due to poor insulation. Current may be induced in these circuits 40, 42 in response to magnetic flux flowing within the flux path FI.
- the first circuit 40 may be formed on the left side of FIG. 3 by a left bar portion 46 of rotor bars 30 and a left bar portion 52 of bar 32 and end ring 34. The first circuit 40 is completed by a failure in the insulation between bars 30 and 32 (shown schematically as resistor 38 in FIG. 3 joining bars 30 and 32).
- the second circuit 42 may be formed on the right side of FIG. 3 by bar portions 48 and 50 (of rotor bars 30 and 32) and right end ring 44.
- the second circuit 42 is completed by resistor 38 joining bars 30 and 32).
- the first circuit 40 encloses flux from the left leg (pole) of electromagnet 12. Where current "i" flows in a positive direction of the winding 36, an opposing current will flow as shown in the first circuit 40.
- the second circuit 42 encloses from the right leg (pole) of electromagnet 12. Where current "i" flows in a positive direction of the winding 36, an opposing current will flow as shown in the second circuit 42.
- the induced voltage may be measured through the use of a bifilar winding 36. While an energizing voltage is applied to a first conductor of the bifilar winding, the voltage (from which real power may be determined) is measured on a second conductor of the bifilar winding.
- the use of a bifilar winding reduces error in real power measurement by eliminating PR loss existing in the first conductor from the real power calculation.
- a pair of electromagnets 60, 62 are applied across a pair of adjacent teeth 22, 24 of the rotor 16 as shown in FIGs. 4 and 5.
- a first electromagnet 60 may be applied across the pair of teeth 22, 24 on one end of the rotor 16 while a second electromagnet 62 is applied across the same set of teeth 22, 24 at an opposing end of the rotor 16.
- Using a pair of electromagnets 60, 62 produces a pair of flux paths (one at each end between opposing legs of the respective electromagnets 60, 62).
- each electromagnet 60, 62 is provided with a separate winding 72, 74 (shown in FIG. 6).
- the windings 72, 74 of the electromagnets 60, 62 are connected in series and are wound in an opposite direction. Placing the winding 72, 74 in series with an opposing winding direction allows for a net magnetic flux of zero in each tooth.
- electromagnets 60, 62 are placed at opposite ends of the lamination stack, no net flux linkage exists with the rotor as long as the rotor is well insulated.
- the flux return path between electromagnets 62 and 64 is across the stack of laminations. In the case illustrated by FIG. 6, not only is the net flux in each tooth equal to zero, but the net flux at each end of the stack is also zero. In this case the flux return path is through the larninations, rather than across them, since this is the path of minimum reluctance.
- the electromagnets 60, 62 are shown as spanning teeth 22 and 24.
- a first bar 28 is shown extending past both electromagnets 60, 62 on a front side.
- a second bar 30 passes through the two electromagnets 60, 62.
- a t rd bar 32 is shown extending past both electromagnets 60, 62 on a rear side.
- End rings 34, 44 connect the opposite ends of the bars 28, 30, 32.
- a pair of resistors 84, 86 are used to indicate poor insulation. Resistor 84 is used to indicate poor insulation between bars 30 and 32. Resistor 86 is used to indicate poor insulation between bars 30 and 28.
- a first circuit 88 includes a first portion 72 of bar 28, resistor 86, a first portion 76 of bar 30 and end ring 34.
- a second circuit 90 includes a second portion 74 of bar 28, end ring 44, a second portion of bar 30, end ring 44, a second portion 82 of bar 32 and resistor 84.
- a fourth circuit 94 includes the first portion 76 of bar 30, resistor 84, a first portion 80 of bar 32 and end ring 34.
- flux from the first pole 64 of the first electromagnet 60 is enclosed by the first circuit 88, while flux from the first pole 68 of the second electromagnet 62 is enclosed by the second circuit 90. Since the flux from the first pole 64 is equal and opposite to flux from the first pole 68, there is no net flux through the large circuit formed by bars 28 and 30 and end rings 34 and 44. Since no flux is enclosed by the large circuit, no current flows around the large circuit. For the same reason, no current flows around the large circuit formed by bars 30 and 32 and end rings 34 and 44. Also, since the net flux of the four poles 64, 66, 68, 70 of the two electromagnets 60, 62 is zero, there is not current flowing through the large circuit formed by outside bars 28 and 32 and end rings 34 and 44.
- the controller 14 applies a voltage to the input shown in FIG. 6 of the pair of electromagnets 60, 62. Upon applying the voltage, the controller 14, in turn, measures a magnitude and phase of any current, "i", flowing through the electromagnets 60, 62. From the voltage and magnitude and phase of the current the controller 14 measures a real power absorbed by the rotor 16 as a measure of insulation quality.
- resistors 84, 86 are both open circuits (i.e., the insulation between bars 28, 30, 32 is of a very high quality), then very little real power will be absorbed by the rotor 16 when the electromagnets 60, 62 are placed over the first set of teeth 22, 24. If only one resistor (e.g., resistor 84) is open circuited, then a lesser amount of power will be absorbed and the presence of a short between only one set of bars (i.e., bars 28 and 30) may be detected.
- the electromagnets 60, 62 may be moved to the next set of teeth 20, 22. Once moved to the next set of teeth 20, 22, the insulation of another set of bars 26, 28, 30 may be tested.
- one of the electromagnets 60, 62 may be removed from a set of teeth to check for broken rotor bars.
- the second electromagnet 62 may be detached from the rotor 16. Then, if bar 30 is open, the loop formed by bars 28 and 32 will have no net flux, and no rotor currents will result (the electromagnet, 60 or 62 should be placed in the center of the stack, straddling the box 30).
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Tests Of Circuit Breakers, Generators, And Electric Motors (AREA)
- Testing Relating To Insulation (AREA)
Abstract
Description
Claims
Priority Applications (5)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CA002376651A CA2376651A1 (en) | 2000-04-20 | 2000-04-20 | Insulation tester for squirrel cage rotors |
JP2001578969A JP2003532081A (en) | 2000-04-20 | 2000-04-20 | Insulation tester for cage rotor |
EP00928217A EP1279041A1 (en) | 2000-04-20 | 2000-04-20 | Insulation tester for squirrel cage rotors |
PCT/US2000/010549 WO2001081934A1 (en) | 2000-04-20 | 2000-04-20 | Insulation tester for squirrel cage rotors |
CN00819771.7A CN1454319A (en) | 2000-04-20 | 2000-04-20 | Insulation tester for squirrel cage rotors |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
PCT/US2000/010549 WO2001081934A1 (en) | 2000-04-20 | 2000-04-20 | Insulation tester for squirrel cage rotors |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2001081934A1 true WO2001081934A1 (en) | 2001-11-01 |
Family
ID=21741296
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/US2000/010549 WO2001081934A1 (en) | 2000-04-20 | 2000-04-20 | Insulation tester for squirrel cage rotors |
Country Status (5)
Country | Link |
---|---|
EP (1) | EP1279041A1 (en) |
JP (1) | JP2003532081A (en) |
CN (1) | CN1454319A (en) |
CA (1) | CA2376651A1 (en) |
WO (1) | WO2001081934A1 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CH699666A1 (en) * | 2008-10-08 | 2010-04-15 | Alstom Technology Ltd | Method and device for the detection of short circuits in the stator laminated core of electric machines. |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2016143218A1 (en) * | 2015-03-12 | 2016-09-15 | 三菱電機株式会社 | Insulation inspection apparatus for electric motor and insulation inspection method for electric motor |
JP6678812B2 (en) * | 2017-03-23 | 2020-04-08 | 三菱電機株式会社 | Measuring device, measuring method, and motor manufacturing method |
CN110007191A (en) * | 2019-04-12 | 2019-07-12 | 湖北江山华科数字设备科技有限公司 | A kind of machine winding coil insulation fault location method |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3875511A (en) * | 1971-12-20 | 1975-04-01 | Gen Electric | Apparatus and method for testing dynamoelectric machine rotors |
JPS5947952A (en) * | 1982-09-09 | 1984-03-17 | Toshiba Corp | Testing method for squirrel-cage rotor |
US4801877A (en) * | 1986-05-06 | 1989-01-31 | General Electric Company | Method and apparatus for testing dynamoelectric machine rotors |
RU1793397C (en) * | 1990-12-17 | 1993-02-07 | Кировский Политехнический Институт | Device for determining the damage degree of induction motor rotor squirrel-cage rods |
US5990688A (en) * | 1998-01-09 | 1999-11-23 | Hydro-Quebec | Apparatus and method for evaluation a condition of a magnetic circuit of an electric machine |
-
2000
- 2000-04-20 JP JP2001578969A patent/JP2003532081A/en active Pending
- 2000-04-20 WO PCT/US2000/010549 patent/WO2001081934A1/en active Application Filing
- 2000-04-20 CN CN00819771.7A patent/CN1454319A/en active Pending
- 2000-04-20 CA CA002376651A patent/CA2376651A1/en not_active Abandoned
- 2000-04-20 EP EP00928217A patent/EP1279041A1/en not_active Withdrawn
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3875511A (en) * | 1971-12-20 | 1975-04-01 | Gen Electric | Apparatus and method for testing dynamoelectric machine rotors |
JPS5947952A (en) * | 1982-09-09 | 1984-03-17 | Toshiba Corp | Testing method for squirrel-cage rotor |
US4801877A (en) * | 1986-05-06 | 1989-01-31 | General Electric Company | Method and apparatus for testing dynamoelectric machine rotors |
RU1793397C (en) * | 1990-12-17 | 1993-02-07 | Кировский Политехнический Институт | Device for determining the damage degree of induction motor rotor squirrel-cage rods |
US5990688A (en) * | 1998-01-09 | 1999-11-23 | Hydro-Quebec | Apparatus and method for evaluation a condition of a magnetic circuit of an electric machine |
Non-Patent Citations (1)
Title |
---|
PATENT ABSTRACTS OF JAPAN vol. 008, no. 139 (E - 253) 28 June 1984 (1984-06-28) * |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CH699666A1 (en) * | 2008-10-08 | 2010-04-15 | Alstom Technology Ltd | Method and device for the detection of short circuits in the stator laminated core of electric machines. |
WO2010040767A1 (en) * | 2008-10-08 | 2010-04-15 | Alstom Technology Ltd. | Method and device for detecting short-circuits in the stator core of electric machines |
Also Published As
Publication number | Publication date |
---|---|
CN1454319A (en) | 2003-11-05 |
CA2376651A1 (en) | 2001-11-01 |
JP2003532081A (en) | 2003-10-28 |
EP1279041A1 (en) | 2003-01-29 |
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