Apparatus and method for measuring performance parameters of electric motors

Claim 3

The method of claim 1, wherein the scaling factor is about 1.515.

Claim 6

The method of claim 3, wherein the scaling factor is about 0.860.

Claim 9

The method of claim 5, wherein the power scaling factor is about 1.515 and the voltage is about 0.860.

Claim 12

The method of claim 7, wherein the single-phase input power and the scaled single-phase input power are related by a power scaling factor of 1.515 and the single-phase input voltage and the scaled single-phase input voltage are related by a voltage scaling factor of 0.860.

Claim 13

The method of claim 7, wherein the performance parameters include efficiency, full load current, full load input power, full load output power, full load output torque, speed, slip, power factor, friction and windage power loss, iron (hysteresis) power loss, secondary rotor power loss.

Claim 14

A test apparatus for testing a three-phase alternating current motor, having field windings and a rotor, without mechanically coupling the rotor to any instrumentality, the test apparatus comprising: a. a source of single-phase alternating current with a variable frequency; b. connector means for connecting the source of single-phase alternating current to the field windings of the motor; c. control means for varying the frequency of the source of single-phase alternating current from a predetermined rated maximum frequency toward zero frequency; d. measuring means for measuring single-phase input power levels for various frequencies of input current; and e. computer means connected to the measuring means for receiving the single-phase input power levels, multiplying the single-phase input power levels by a scaling factor to produce scaled single-phase input power levels that correlate with conventional locked rotor input power levels resulting from a conventional locked rotor test using three-phase alternating current, calculating performance parameters for the motor from the scaled single-phase input power levels, and comparing the performance parameters to predetermined limits in order to determine whether the motor failed.

Claim 15

A test apparatus for testing a three-phase alternating current motor, having field windings and a rotor, without mechanically coupling the rotor to any instrumentality, the test apparatus comprising: a. a source of single-phase alternating current with a variable frequency; b. connector means for connecting the source of single-phase alternating current to the field windings of the motor; c. control means for varying the frequency of the source of single-phase alternating current from a predetermined rated maximum frequency toward zero frequency; d. measuring means for measuring single-phase input power levels for various frequencies of input current; and e. computer means connected to the measuring means for receiving the single-phase input power levels, multiplying the single-phase input power levels by a scaling factor to produce scaled single-phase input power levels that correlate with conventional locked rotor input power levels resulting from a conventional locked rotor test using three-phase alternating current, calculating performance parameters for the motor from the scaled single-phase input power levels, and comparing the performance parameters to predetermined limits in order to determine whether the motor failed.

Claim 16

The apparatus of claim 10, wherein the scaling factor is 1.515.

Claim 17

A test apparatus for testing a three-phase alternating current motor, having field windings and a rotor, without mechanically coupling the rotor to any instrumentality, the test apparatus comprising: a. a source of single-phase alternating current, with a variable frequency; b. connector means for connecting the source of single-phase alternating current to the field windings of the motor; c. control means for varying the frequency of the source of single-phase alternating current from a predetermined rated maximum frequency toward zero frequency; d. measuring means for measuring single-phase input voltage levels for various frequencies of input current; and e. computer means connected to the measuring means for receiving the single-phase input voltage levels, multiplying the single-phase input voltage levels by a scaling factor to produce scaled single-phase input voltage levels that correlate with conventional locked rotor input power levels resulting from a conventional locked rotor test using three-phase alternating current, calculating performance parameters for the motor from the scaled single-phase input voltage levels, and comparing the performance parameters to predetermined limits in order to determine whether the motor failed.

Claim 18

A test apparatus for testing a three-phase alternating current motor, having field windings and a rotor, without mechanically coupling the rotor to any instrumentality, the test apparatus comprising: a. a source of single-phase alternating current, with a variable frequency; b. connector means for connecting the source of single-phase alternating current to the field windings of the motor; c. control means for varying the frequency of the source of single-phase alternating current from a predetermined rated maximum frequency toward zero frequency; d. measuring means for measuring single-phase input voltage levels for various frequencies of input current; and e. computer means connected to the measuring means for receiving the single-phase input voltage levels, multiplying the single-phase input voltage levels by a scaling factor to produce scaled single-phase input voltage levels that correlate with conventional locked rotor input power levels resulting from a conventional locked rotor test using three-phase alternating current, calculating performance parameters for the motor from the scaled single-phase input voltage levels, and comparing the performance parameters to predetermined limits in order to determine whether the motor failed.

Claim 19

The apparatus of claim 12, wherein the scaling factor is 0.860.

Claim 20

A test apparatus for testing a three-phase alternating current motor, having field windings and a rotor, without mechanically coupling the rotor to any instrumentality, the test apparatus comprising: a. a source of single-phase alternating current, with a variable frequency; b. connector means for connecting the source of single-phase alternating current to the field windings of the motor; c. control means for varying the frequency of the source of single-phase alternating current from a predetermined rated maximum frequency toward zero frequency; d. measuring means for measuring single-phase input power levels for various frequencies of input current; and e. computer means connected to the measuring means: i. for receiving the single-phase input power levels and multiplying the single-phase input power levels by a power scaling factor to produce scaled single-phase input power levels that correlate with conventional locked rotor input power levels resulting from a conventional locked rotor test using three-phase alternating current and for receiving the single-phase input voltage levels; p2 ii. for receiving the single-phase input voltage levels and multiplying the single-phase input voltage levels by a voltage scaling factor to produce scaled single-phase input voltage levels that correlate with conventional locked rotor input voltage levels resulting from a conventional locked rotor test using three-phase alternating current; iii. for calculating performance parameters of the motor using the scaled single-phase input power levels and the scaled single-phase input voltage levels; iv. for comparing the performance parameters to predetermined limits in order to determine whether the motor failed.

Claim 21

A test apparatus for testing a three-phase alternating current motor, having field windings and a rotor, without mechanically coupling the rotor to any instrumentality, the test apparatus comprising: a. a source of single-phase alternating current, with a variable frequency; b. connector means for connecting the source of single-phase alternating current to the field windings of the motor; c. control means for varying the frequency of the source of single-phase alternating current from a predetermined rated maximum frequency toward zero frequency; d. measuring means for measuring single-phase input power levels for various frequencies of input current; and e. computer means connected to the measuring means: i. for receiving the single-phase input power levels and multiplying the single-phase input power levels by a power scaling factor to produce scaled single-phase input power levels that correlate with conventional locked rotor input power levels resulting from a conventional locked rotor test using three-phase alternating current and for receiving the single-phase input voltage levels; p2 ii. for receiving the single-phase input voltage levels and multiplying the single-phase input voltage levels by a voltage scaling factor to produce scaled single-phase input voltage levels that correlate with conventional locked rotor input voltage levels resulting from a conventional locked rotor test using three-phase alternating current; iii. for calculating performance parameters of the motor using the scaled single-phase input power levels and the scaled single-phase input voltage levels; iv. for comparing the performance parameters to predetermined limits in order to determine whether the motor failed.

Claim 22

A test apparatus for determining performance parameters of a three-phase alternating current electric motor with a rated electrical input power and with a predetermined stray load loss and having field windings and a rotor, wherein the rotor is not mechanically coupled to any instrumentality, the test apparatus comprising: a. resistance measuring means for determining the direct current resistance of the field windings; b. a source of three-phase alternating current, with a variable voltage; c. a source of single-phase alternating current, with a variable frequency; d. connector means for selectively connecting the source of three-phase alternating current and the source of single-phase alternating current to the field windings of the motor; e. no load measuring means for measuring the no load input power levels for various no load input voltage levels when the source of three-phase alternating current is connected to the field windings; f. single-phase measuring means for measuring the single-phase input power levels and single-phase input voltage levels for various frequencies of the single-phase alternating current when the source of single-phase alternating current is connected to the field windings; d. computer means connected to the resistance measuring means, to the no load measuring means and to the single-phase measuring means for receiving the direct current resistance, the no load input power levels, the single-phase input power levels, and the single-phase input voltage levels, wherein the computer multiplies the single-phase input power levels by a power scaling factor to produce scaled single-phase input power levels that correlate with conventional locked rotor input power levels resulting from a conventional locked rotor test using three-phase alternating current and multiplies the single-phase input voltage levels by a voltage scaling factor to produce scaled single-phase input voltage levels that correlate with conventional locked rotor input voltage levels resulting from a conventional locked rotor test using three-phase alternating current, wherein the computer calculates the performance parameter of the motor from the stray load loss, the direct current resistance of the field windings, no load input power, the no load input voltage, the scaled single-phase input power, and the scaled single-phase input voltage, and wherein the computer compares the performance parameters to predetermined limits in order to determine whether the motor failed.

Claim 23

A test apparatus for determining performance parameters of a three-phase alternating current electric motor with a rated electrical input power and with a predetermined stray load loss and having field windings and a rotor, wherein the rotor is not mechanically coupled to any instrumentality, the test apparatus comprising: a. resistance measuring means for determining the direct current resistance of the field windings; b. a source of three-phase alternating current, with a variable voltage; c. a source of single-phase alternating current, with a variable frequency; d. connector means for selectively connecting the source of three-phase alternating current and the source of single-phase alternating current to the field windings of the motor; e. no load measuring means for measuring the no load input power levels for various no load input voltage levels when the source of three-phase alternating current is connected to the field windings; f. single-phase measuring means for measuring the single-phase input power levels and single-phase input voltage levels for various frequencies of the single-phase alternating current when the source of single-phase alternating current is connected to the field windings; d. computer means connected to the resistance measuring means, to the no load measuring means and to the single-phase measuring means for receiving the direct current resistance, the no load input power levels, the single-phase input power levels, and the single-phase input voltage levels, wherein the computer multiplies the single-phase input power levels by a power scaling factor to produce scaled single-phase input power levels that correlate with conventional locked rotor input power levels resulting from a conventional locked rotor test using three-phase alternating current and multiplies the single-phase input voltage levels by a voltage scaling factor to produce scaled single-phase input voltage levels that correlate with conventional locked rotor input voltage levels resulting from a conventional locked rotor test using three-phase alternating current, wherein the computer calculates the performance parameter of the motor from the stray load loss, the direct current resistance of the field windings, no load input power, the no load input voltage, the scaled single-phase input power, and the scaled single-phase input voltage, and wherein the computer compares the performance parameters to predetermined limits in order to determine whether the motor failed.

Claim 24

The test apparatus of claim 15, wherein the power scaling factor is 1.515 and the voltage scaling factor is 0.860.

Claim 25

The method of claim 15, wherein the performance parameters include efficiency, full load current, full load input power, full load output power, full load output torque, speed, slip, power factor, friction and windage power loss, iron (hysteresis) power loss, secondary rotor power loss.