Test procedures for converter-fed three phase cage induction motors
1 Scope
This standard specifies the test requirements, preparation before test, no-load test, locked-rotor test, load test, determination of loss and efficiency, thermal test, maximum torque and minimum torque test, etc. of converter-fed three phase cage induction motors.
This standard is applicable to converter-fed three phase cage induction motors.
This standards is not applicable to traction motors.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 755-2008 Rotating electrical machines - Rating and performance
GB/T 1032-2012 Test procedures for three-phase induction motors
GB/T 10068-2008 Mechanical vibration of certain machines with shaft heights 56 mm and higher - Measurement, evaluation and limits of vibration severity
GB/T 10069.1-2006 Measurement of airborne noise emitted by rotating electrical machines and the noise limits - Part 1: Method for the measurement of airborne noise emitted by rotating electrical machines
GB/T 18039.4-2017 Electromagnetic compatibility - Environment - Compatibility levels in industrial plants for low-frequency conducted disturbances
GB/T 21211-2017 Equivalent loading and superposition techniques - Indirect testing to determine temperature rise of rotating electrical machines
GB/T 25442-2010 Standard methods for determining losses and efficiency of rotating electrical machines from tests (excluding machines for traction vehicles)
GB/T 32877-2016 Specific test methods for determining losses and efficiency of converter-fed AC induction motors
GB/T 34861-2017 Specific methods for determining separate losses of large machines from tests
3 Terms, definitions and symbols
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in GB/T 755-2008, GB/T 1032-2012, GB/T 32877-2016 and the following apply.
3.1.1
converter
power conversion device composed of one or more electronic switch(es), relevant element, transformer, filter, phase conversion auxiliary device, controller and protective and auxiliary apparatus (if any), for changing one or more power characteristic(s)
3.1.2
base rating
rating under the specified rotation speed, fundamental frequency voltage and torque or in the base operating point of power [See Point (3) in Figure 1]
Keys:
(1) - the torque value is limited by the permissible temperature and voltage boost limit of the motor at the minimum speed;
(2) - the constant-torque minimum speed is limited by the permissible temperature of motor;
(3) - the base rating is positioned on the high-speed terminal of constant torque;
(4) - the constant-power maximum operating speed is limited by the maximum permissible speed.
Figure 1 Basic elements of rating
3.1.3
breakaway torque
torque generated by the motor at zero rotation speed under the action of converter
3.1.4
constant-power speed range
speed range where the driving system can maintain the basically constant power
3.1.5
constant-torque speed range
speed range where the driving system can maintain the basically constant torque
3.1.6
voltage boost
voltage increment where the controllable output voltage is higher than the voltage obtained according to frequency
Note: It may be used for all frequencies. Generally, it is used for low frequency to compensate the pressure drop of stator winding.
3.1.7
fundamental frequency
frequency at reference rotation speed for converter-fed motor
3.1.8
fundamental losses
losses of motor at rated sinusoidal wave voltage and fundamental frequency (generally 50 Hz or 60 Hz), excluding harmonics
Note: The losses determined according to GB/T 1032-2012 are the fundamental losses.
3.1.9
harmonic losses
additional losses caused by non-sinusoidal voltage and current waveform with converter supply
Note: Harmonic loss is additional loss to fundamental iron loss, fundamental rotor loss, fundamental stator loss and stray loss, and is related to the harmonic quantity contained in the output quantity of converter.
3.2 Symbols
For the purposes of this document, the following symbols and units apply:
cosφ——the power factor;
f——the frequency, Hz;
fN——the rated frequency of motor, Hz;
fr——the maximum frequency of measuring equipment, Hz;
fsw——the switching frequency, Hz.
fMot——the fundamental frequency of motor, Hz;
I——the stator line current, A;
I0—— the no-load line current, A;
IK——the locked-rotor line current, A;
IN——the rated current, A;
K1——the reciprocal of the temperature coefficient of resistance for the conductor material at 0°C;
Copper K1=235;
Aluminum K1=225, unless otherwise specified;
kd——the corrected value of torque reading, N·m;
J——the moment of inertia, kg·m2;
n——the rotation speed measured during test, r/min;
p——the number of pole pairs for motor;
P1——the input power, W;
P1C——the input power with converter supply, W;
P2——the output power, W;
P2C——the output power with converter supply, W;
PN——the input (rated) power, W;
PC——the constant losses, W;
PCC——the constant losses with converter supply, W;
PFe——the iron losses, W;
Pfw0——the air friction losses at synchronous speed, W;
Pfw——the air friction losses, W;
PL——the load losses, W;
PLr——the residual losses, W;
PLrC——the residual losses with converter supply, W;
PLL——the stray-load losses, W;
PLLC——the stray-load losses with converter supply, W;
PHL——the additional harmonic losses with converter supply, W;
PHLLoad——the additional load harmonic losses, W;
PHLNO-Load——the additional constant harmonic losses, W;
P0——the no-load input power, W;
PK——the input power at locked rotor, W;
Ps——I2R losses of stator winding at test temperature, W;
Pr——I2R losses of rotor winding at test temperature, W;
Ps, θ——I2R losses of stator winding at the specified temperature (θs), W;
Pr, θ——I2R losses of rotor winding at the specified temperature (θs), W;
PTsin——the corrected total fundamental losses, W;
PTTest-converter——the corrected total fundamental losses with converter supply, W;
rHL——the percentage of harmonic voltage losses over standard sinusoidal wave voltage losses (rounded to the nearest integer);
R1——the initial terminal resistance of stator winding at temperature θ1, Ω;
RN——the terminal resistance of stator winding at the end of rated load thermal test, Ω;
Rt——the terminal resistance of stator winding measured (calculated) at test temperature, Ω;
R0——the terminal resistance of stator winding for no-load test (each voltage point), Ω;
s——the slip ratio;
ss——the slip ratio where converted to the specified temperature θs;
Td——the torque reading, N·m;
Tc——the torque correction, N·m
T——the corrected torque, N·m;
TK——the locked-rotor torque, N·m;
Tmax——the maximum torque, N·m;
Foreword i
1 Scope
2 Normative references
3 Terms, definitions and symbols
3.1 Terms and definitions
3.2 Symbols
4 Test requirements
4.1 Test power supply
4.2 Measuring instruments
4.3 Setting of converter
4.4 Measurement requirements
5 Test preparation
5.1 Determination of insulation resistance
5.2 Determination of DC terminal resistance of winding under initial (cold) state
5.3 Test resistance
5.4 Winding temperature
5.5 Correction to reference coolant temperature
6 No-load test
6.1 No-load test condition
6.2 Determination of no-load current and no-load loss
6.3 Determination of constant loss PC
6.4 Determination of air friction loss Pfw
6.5 Determination of iron loss PFe
7 Locked-rotor test
7.1 Locked-rotor test at rated frequency
7.2 Breakaway torque test under converter supply
8 Load test
8.1 General
8.2 Rated load test
8.3 Load characteristic curve
8.4 Determination of load characteristic of converter-fed motor
9 Determination of losses
9.1 General
9.2 Iron loss PFe
9.3 Air friction loss Pfw
9.4 Load loss
9.5 Stray-load losses PLL
9.6 Total loss PT
10 Determination of efficiency
10.1 Test methods
10.2 Method 2-3-A: Loss summation method for test converter supply
10.3 Method 2-3-B: Loss summation method for specific converter supply
10.4 Method 2-3-C: Input-output method
10.5 Method 2-3-D: Calorimetric method
11 Thermal test
11.1 Purpose
11.2 General specification
11.3 Determination of coolant temperature during thermal test
11.4 Determination of coolant temperature at the end of the test
11.5 Determination for temperature of motor winding and other parts
11.6 Thermal test method
11.7 Temperature rise
11.8 Determination of winding operating temperature θw at rated load
12 Determination of maximum torque
12.1 General
12.2 Dynamometer or calibrated DC motor
12.3 Torque meter method
12.4 Torque tachometer method
12.5 Circle diagram calculation method
12.6 Conversion of maximum torque
13 Determination of minimum torque
13.1 General
13.2 Dynamometer or calibrated DC motor method
13.3 Torque meter method
13.4 Torque tachometer method
13.5 Conversion of minimum torque
14 Other tests
14.1 Over speed test
14.2 Determination of noise
14.3 Determination of vibration
14.4 Temporary over torque test
14.5 Withstanding voltage test
14.6 Determination of moment of inertia
14.7 Determination of shaft voltage
14.8 Determination of bearing current
Annex A (Normative) Instrument loss and error correction method
Annex B (Normative) Dynamometer torque reading correction
Annex C (Informative) Measurement of slip ratio of induction motor
Annex D (informative) Linear regression analysis
Annex E (Informative) Test frequency converter output voltage
Figure 1 Basic elements of rating
Figure 2 No-load characteristic curve
Figure 3 Locked rotor characteristic curve
Figure 4 Load characteristic curve
Figure 5 Graduation of residual loss data
Figure 6 Determination of θN with dropping-current load method
Figure 7 Test circuit for stator superposing-frequency method
Figure 8 Shaft voltage measurement diagram
Figure 9 Bearing current measurement diagram
Figure A.1 Schematic diagram of voltmeter connection near load terminal
Figure A.2 Schematic diagram of ammeter connection near load terminal
Figure C.1 Principle block diagram of slip ratio test system
Figure E.1 PDS schematic diagram
Figure E.2 Schematic diagram of voltage generation system
Figure E.3 Sine wave voltage setpoint and linear extension voltage
Figure E.4 Voltage settings and extended reference voltages
Figure E.5 Pulse mode of motor terminal voltage
Figure E.6 Enlarged marker area of Figure E.5
Figure E.7 Inverter filter terminal voltage
Table 1 Selection of tramegger
Table 2 Reference temperature
Table 3 Test methods
Table 4 Time interval
Table D.1 Linear regression data
