GB/T 5171.21-2016 PDF English
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Small power motors - Part 21: General test methods
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GB/T 5171.21-2016: PDF in English (GBT 5171.21-2016) GB/T 5171.21-2016
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 29.160.30
K 20
Small power motors - Part 21: General test methods
ISSUED ON: AUGUST 29, 2016
IMPLEMENTED ON: MARCH 01, 2017
Issued by: General Administration of Quality Supervision, Inspection and
Quarantine;
Standardization Administration of the People's Republic of
China.
Table of Contents
Foreword ... 4
1 Scope ... 5
2 Normative references ... 5
3 Terms and definitions, symbols ... 6
3.1 Terms and definitions ... 6
3.2 Symbols ... 8
4 Basic requirements for test ... 11
4.1 Test ambient conditions ... 11
4.2 Test power ... 11
4.3 Use of measuring instruments... 12
5 Test preparation ... 20
5.1 Determination of insulation resistance ... 20
5.2 Determination of cold-state winding temperature θ1 and cold-state winding
resistance R1 ... 21
6 Temperature rise test ... 21
6.1 Overview ... 21
6.2 General description ... 21
6.3 Determination of cooling medium temperature at the end of temperature rise
test ... 22
6.4 Temperature measurement methods for motor winding and other parts ... 22
6.5 Temperature rise test method ... 23
6.6 Calculation of winding working temperature θ2 ... 26
6.7 Calculation of winding temperature rise Δθ ... 27
6.8 Corrected to reference cooling medium temperature ... 27
7 Determination of efficiency ... 28
7.1 Overview ... 28
7.2 Direct method (method A) ... 29
7.3 Loss analysis method (method B) ... 31
7.4 Calculation of AC motor power factor ... 41
8 Locked-rotor test ... 41
9 Other test items ... 42
9.1 Dimension inspection ... 42
9.2 Short-time over-torque test ... 46
9.3 Determination of maximum torque ... 46
9.4 Determination of minimum torque ... 47
9.5 Determination of moment of inertia ... 49
9.6 Magnetic stability inspection of permanent magnet motors ... 50
9.7 Determination of noise ... 50
9.8 Determination of vibration ... 51
9.9 Electric strength test ... 51
9.10 Repeat electric strength test ... 52
9.11 Inter-turn insulation electric strength test ... 52
9.12 Leakage current test at working temperature ... 53
9.13 Accidental overcurrent test ... 55
9.14 Over-speed test ... 55
9.15 Protection level test ... 56
9.16 Damp heat test ... 56
9.17 Other ambient tests ... 56
9.18 Other safety tests ... 56
9.19 Operating time limit test ... 56
Annex A (normative) Correction methods for instrument loss ... 60
Annex B (normative) Determination of correction value Tc of dynamometer
torque reading ... 62
Annex C (normative) Specification for selection, preparation, arrangement,
installation and connection of thermocouples ... 63
Annex D (informative) Test report template for loss analysis method (method B)
... 66
Bibliography ... 68
Small power motors - Part 21: General test methods
1 Scope
This Part of GB/T 5171 specifies terms and definitions, symbols involved in
general test methods for small power motors, basic requirements for the test,
test preparation, temperature rise test, efficiency determination, as well as
locked-rotor test and other test methods.
This Part is applicable to the products defined in GB/T 5171.1.
The special test items and methods of various types of small power motors that
are not specified in this Part need to be supplemented in the test method
standards for this type of small power 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 755, Rotating electrical machines - Rating and performance
GB/T 1958, Geometrical Product Specifications (GPS) - Geometrical
tolerance - Verification
GB/T 2423 (all parts), Environmental testing - Part 2: Test methods
GB/T 2828.1, Sampling procedures for inspection by attributes - Part 1:
Sampling schemes indexed by acceptance quality limit (AQL) for lot-by-lot
inspection
GB/T 4942.1, Degrees of Protection Provided by the Integral Design of
Rotating Electrical Machined (IP Code) - Classification
GB/T 5171.1, Small Power Motors - Part 1: General Technical Requirements
GB/T 10069.1, 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 12113-2003, Methods of measurement of touch current and protective
[GB/T 2900.25-2008, definition 411-53-28]
3.1.5 locked-rotor test
a test to determine the locked-rotor torque and the locked-rotor current, when
the motor is energized and the rotor is blocked
[GB/T 2900.25-2008, definition 411-53-32]
3.1.6 over-speed test
a test carried out on the motor to determine whether the motor rotor can meet
the specified overspeed requirements
[GB/T 2900.25-2008, definition 411-53-39]
3.1.7 short-time over-torque test
a test to determine the ability of the motor to withstand the specified over-torque
multiples within a specified time
[GB/T 2900.27-2008, definition 9.7]
3.1.8 accidental over-current test
a test to determine the ability of the motor to withstand the specified overcurrent
multiples within a specified time
[GB/T 2900.27-2008, definition 9.9]
3.1.9 operating time limit test
a test to determine the normal operation period that the manufacturer
guarantees to the user under the specified conditions
[GB/T 2900.27-2008, definition 9.12]
3.1.10 no-load test
a test without effective mechanical output on the shaft when the motor is
running
3.1.11 line-to-line resistance
the arithmetic average of the resistance between the terminals of each two-
phase power supply connection of a multi-phase AC motor
NOTE 1: For Y-connection three-phase motors, the phase resistance is 0.5 times the line-
to-line resistance. For Δ-connection three-phase motors, the phase resistance is 1.5 times
Pc - Constant loss (W);
Pfe - Iron consumption (W);
Pfw - Friction and wind resistance loss (W);
Pfw0 - Friction and windage loss (W) at synchronous speed;
Pk - Locked-rotor input power (W);
PLL - Additional load loss (W);
PLr - Stray loss (W);
Pr - Rotor winding loss (W);
Pr,θ - Rotor winding loss (W) corrected to 25°C reference cooling medium
temperature;
Ps - Stator winding loss (W);
Ps,θ - Stator winding loss (W) corrected to 25°C reference cooling medium
temperature;
PT - Total loss (W);
P0 - No-load input power (W);
P1 - Input power (W);
P1,θ - Input power (W) corrected to 25°C reference cooling medium temperature;
P2 - Output power (W);
P2c - Corrected output power (W);
p - Number of pole pairs;
Q - Gravity of code and container (N);
R - Winding resistance;
Rll,0 - Interpolated winding resistance (Ω) during no-load test (each voltage
point);
R0 - Winding resistance (Ω) during no-load test;
R1 – Cold-state winding resistance (Ω);
R2 - In the temperature rise test, the winding resistance measured after the
n - Harmonic order (does not include the multiples of 3 and 3 for three-phase
AC motors);
k=13.
When conducting temperature rise and efficiency tests, the voltage tolerance of
the AC power supply for the test shall not be greater than 0.5%. The frequency
fluctuation of the AC power supply shall be within ±0.1% of the rated frequency.
The average power supply frequency shall be within ±0.1% of the test frequency.
4.2.2 Three-phase AC power supply
For three-phase AC power supply, in addition to meeting the requirements in
4.2.1, the negative sequence component of the three-phase voltage system
shall be less than 0.5% of the positive sequence component, and the influence
of zero sequence component shall be eliminated. The negative sequence
component of the measuring current system can be used to replace the
negative sequence component of the measuring voltage system. The negative
sequence component of the current system shall not exceed 2.5% of the
positive sequence component.
4.2.3 DC power supply
The DC power supply equipment used in the test shall not exceed 0.5% of the
nominal source voltage and the output voltage tolerance of each output under
half-rated load. For each output, within the specified load range and under the
most unfavorable supply voltage, the load regulation rate is not more than 0.2%.
4.3 Use of measuring instruments
4.3.1 General
The ambient conditions during the test shall be within the range recommended
by the equipment manufacturer. If applicable, temperature corrections shall be
made to the measured values according to the manufacturer's equipment
instructions.
Digital measuring instruments shall be used whenever possible.
Since the accuracy of analog measuring instruments is usually expressed as a
percentage of full scale, the range of the measuring instrument selected during
the test shall be as small as possible as the actual value. The observation value
shall be within one-third of the instrument range to the full-scale range.
The range of the measuring instrument, especially the current sensor, shall be
adapted to the power of the motor being tested.
Parasitic loads shall be minimized through shaft alignment adjustments and the
use of flexible couplings.
4.3.4 Measurement of rotating speed
4.3.4.1 General
The indication error of the speed measuring instrument shall be less than ±0.1%
of the speed range or less than 1r/min. Take the one with the smallest error
between the two.
For asynchronous motors, the induction coil method or flash method can also
be used to measure the slip rate to replace the speed measurement.
The measurement methods of motor speed (slip rate) mainly include:
- Digital speed (or slip) measuring instrument;
- Induction coil method;
- Measuring slip ratio by speed measuring instrument;
- Digital frequency meter;
- Stroboscopic test method.
If the induction coil method or the stroboscopic test method is used to directly
measure the slip rate, the power supply shall be the power supply for the tested
motor. It is not recommended to use direct mechanical contact method that
affects the running state of the motor.
4.3.4.2 Digital speed (or slip rate) measuring instrument method
Install a photoelectric reflective mark, transmissive grating disc or magneto-
electric induction device that does not generate significant load when the motor
rotates on the rotating shaft. Transform the speed signal into pulse signal by
photoelectric sensor or magnetoelectric sensor. The measuring instrument
directly displays the speed (or slip rate) of the tested motor.
4.3.4.3 Induction coil method
For asynchronous motors, a multi-turn coil with iron core can be placed on the
motor casing. And connect with magnetoelectric galvanometer or cathode
oscilloscope. During the test, use a stopwatch to measure the time t (s) required
for the full swing of the galvanometer pointer or the oscilloscope waveform for
N times. The slip rate s is calculated according to formula (3).
thermometers and alcohol thermometers), semiconductor thermometers, and
non-embedded thermocouples or resistance thermometers.
When used to measure the temperature of the parts of the motor, the
thermometer shall be close to the surface of the measured point. To measure
the temperature of the surface of the contact point, the heat conduction from
the measured point to the thermometer shall be as good as possible. Use
thermal insulation material to cover the temperature measurement part of the
thermometer, so as to avoid the influence of the surrounding cooling medium.
When used to measure the temperature of parts with strong alternating or
moving magnetic fields, mercury thermometers shall not be used.
4.3.6.3 Thermocouple method
This method is recommended for the measurement of surface temperature of
motor parts. It is not recommended to use this method to measure the
temperature of the winding.
When using a thermocouple to measure the temperature of the winding, it shall
consider: because the thermocouple reading lags behind the temperature
change of the winding, when the motor is powered off, the temperature of the
thermocouple may continue to rise. Therefore, the temperature of the motor
winding shall record its maximum temperature. The temperature may be
reached after power failure.
The specifications for the selection, preparation, arrangement, installation and
connection of thermocouples are shown in Annex C.
4.3.6.4 Resistance method
The resistance method determines the temperature of the winding based on
the relationship that the resistance of the winding increases correspondingly
after the temperature rises. What it measures is the average temperature of the
winding.
Resistance method includes direct measurement method and live
measurement method (see 6.5.3 and 6.5.4).
4.3.7 Determination of winding resistance
4.3.7.1 General
Winding resistance R can be determined by appropriate methods such as
double-arm bridge, single-arm bridge or DC voltmeter-ammeter method.
For permanent magnet DC motors, R is the total resistance of all coils that load
When measuring the winding insulation resistance, if the beginning and end of
each winding circuit have been led out of the casing, then the insulation group
of each winding circuit to the casing and the windings shall be measured
separately. If the winding has been connected inside the motor, when only the
wire end is drawn out, measure the insulation resistance of the wire end to the
casing.
For capacitor motors, the capacitor shall be connected to the secondary
winding circuit (unless otherwise agreed).
After the insulation resistance measurement is over, the winding shall be
discharged to the ground.
5.2 Determination of cold-state winding temperature θ1 and cold-state
winding resistance R1
Put the motor indoors for a period of time. Use a thermometer to measure the
temperature of the end of the motor winding or the iron core. When the
difference between the measured temperature and the temperature of the
cooling medium does not exceed 2K, then the measured temperature is the
temperature of the cold-state winding θ1. If the temperature of the winding end
or the iron core cannot be measured, the temperature of the casing is allowed
to replace it.
While measuring the cold-state winding temperature θ1, measure the cold-state
winding resistance R1, see 4.3.7.
6 Temperature rise test
6.1 Overview
The purpose of the temperature rise test is to determine the temperature rise of
windings and certain parts of the motor that are higher than the temperature of
the cooling medium when the motor is running under specified load conditions.
The temperature measurement method is selected according to 4.3 and the
relevant provisions of this Clause.
6.2 General description
Measures shall be taken during the test to minimize the change in the
temperature of the cooling medium.
The tested motor shall be protected to block the influence of airflow generated
by other machinery or the surrounding environment on the tested motor.
Generally, a very slight airflow is enough to cause a large deviation in the results
of the temperature rise test. Environmental conditions that cause rapid changes
6.5 Temperature rise test method
6.5.1 Determination of load
6.5.1.1 Overview
The motor shall be able to run under its rated load or less than its rated load.
The motor that can run at multiple speeds shall be able to run at the minimum,
intermediate and maximum speeds with a rated load. During this process, all
parts of the motor shall not reach too high temperature.
For voltage regulating motors that work in a voltage range and motors with
multiple working conditions, the temperature rise test shall be carried out under
the most unfavorable conditions that may occur in normal use.
For motors with thermal protector or thermal fuse without fixed installation
position, during rated load temperature rise test and no-load temperature rise
test, the installation position of the motor shall be such that the thermal protector
or thermal fuse is in a position with the highest possible temperature (usually in
the upper position of the motor winding). During the test, the thermal protector
or thermal fuse is not allowed to operate.
6.5.1.2 Motors with clear rated operating point
This kind of motors use direct method. Apply a rated load to the motor under
test through a dynamometer (or a load motor with a torque measuring
instrument). Test under rated frequency and rated voltage.
For single-phase asynchronous motors running with capacitors, the
temperature rise test shall be assessed at the point of maximum loss. The
maximum loss point is determined by testing among the rated point, the no-load
point, and the intermediate speed points of the above two points.
For capacitor-running asynchronous motors and dual-value capacitor
asynchronous motors, the temperature rise at no load shall also be measured.
6.5.1.3 Motors with actual load
This type of motor has actual load during normal operation, and these actual
loads have a greater impact on the temperature rise of the motor. Therefore,
when the temperature rise test is performed, it is necessary to carry the actual
load and perform the test at the rated frequency and rated voltage.
6.5.2 Duration of various motor temperature rise tests
6.5.2.1 Maximum continuous rating (or S1 working system) motor
The test shall be continued until all parts of the motor reach a thermally stable
6.5.2.6 Locked-rotor temperature rise test
For single-phase asynchronous motors with capacitor start and resistance start,
the locked-rotor temperature rise test shall also be carried out.
The tested motor shall quickly block the rotor in the hot state or after the
temperature rise test is over. Apply a rated voltage. Maintain 5s. Immediately
measure the resistance of the primary and secondary windings to obtain the
temperature rise of the windings.
6.5.3 Determination of the winding resistance R2 and temperature of each
part of motor after the motor is stopped
After the temperature rise test is over, the power shall be cut off immediately.
Carefully arrange the test procedures and the appropriate number of test
personnel. Measure the winding resistance readings and the temperature of
each part of the motor as soon as possible.
From the moment of power failure, if the winding resistance and temperature
are measured within 15s after the power is cut off, then use this resistance value
to calculate the winding temperature rise. The measured temperature of each
part of the motor does not need to be corrected.
If it cannot be measured within 15s, additional readings shall be taken as soon
as possible at intervals of 20s~60s. Plot these readings as a function of time.
Use extrapolation to correct to the moment of power failure. That is, measure
resistance R or temperature θ and corresponding time t. There shall be no less
than 5 points. Draw R=f(t) or θ=f(t) curve on graph paper or semi-logarithmic
graph paper, as shown in Figure 3. The extension curve intersects the vertical
axis. Its intersection point is the resistance value or temperature value at the
moment of power failure.
9.2 Short-time over-torque test
The short-time over-torque test shall be carried out at rated voltage and rated
frequency.
During the test, the motor gradually increases the load in the hot state. The
over-torque multiple and time are in accordance with GB/T 5171.1 or the
product standard of this type of motor.
9.3 Determination of maximum torque
9.3.1 Overview
There are two methods to measure the maximum torque:
- Dynamometer method;
- Torque measuring instrument method.
When measuring, it shall be carried out at rated voltage. If the test voltage
cannot reach the rated voltage, the test voltage shall be controlled within the
range of 0.9~1.1 times the rated voltage. The measured maximum torque value
shall be converted according to 9.3.4.
During the test, the tested motor shall be prevented from overheating and
affecting the accuracy of the measurement.
The terminal voltage of the tested motor shall be measured on its outlet terminal.
9.3.2 Torque measuring instrument method
When measuring the maximum torque with the torque measuring instrument
method, the torque and speed characteristic curve of the tested motor shall be
measured. The maximum torque is calculated from the curve.
The torque and speed characteristic curve can be manually drawn after point-
by-point determination. It can also be drawn directly with an automatic recorder.
The number of measured points shall meet the needs of correctly obtaining
various torques (maximum torque, minimum torque, synchronous torque and
locked-rotor torque). In the vicinity of these torques, the measurement points
shall be as dense as possible.
The characteristics of the load equipment shall be able to measure the entire
torque-speed characteristic curve. Adjustment is easy. Operation is stable. Data
is reliable.
When using DC motor as load, the tested motor is connected with a torque
measuring instrument and a DC motor. The DC motor is separately excited. Its
- Torque measuring instrument method.
During the measurement, the tested motor shall be close to the actual cold state.
The measurement is carried out at the rated frequency and rated voltage. If the
test voltage cannot reach the rated voltage, when the test voltage is within the
range of 0.95~1.05 times the rated voltage, the minimum torque is converted
according to 9.4.4.
During the test, the tested motor shall be prevented from overheating and
affecting the accuracy of the measurement.
The terminal voltage of the tested motor shall be measured on its outlet terminal.
9.4.2 Torque measuring instrument method
When measuring the minimum torque with the torque measuring instrument
method, the speed shall be gradually increased from the locked-rotor state.
Measure the torque and speed characteristic curve of the tested motor. The
minimum torque is obtained from the curve.
During the test, the direction of the tested motor and the load DC motor can be
the same or opposite. First, make the DC motor run at a very low speed. Then
start the tested motor at or close to the rated voltage. Increase or gradually
reduce the load of the tested motor until its rated speed. Other test methods
and requirements are the same as 9.3.3.
9.4.3 Dynamometer method
Use a dynamometer as the load of the tested motor. The minimum torque is
read from the dynamometer.
During the test, connect the tested motor with the coupling of the dynamometer.
First, connect the tested motor to a low voltage. Adjust the terminal voltage (or
excitation current) of the dynamometer, so as to determine the intermediate
speed at which the tested motor has the minimum torque (at a certain speed,
the unit can operate stably at this speed without increasing speed). Disconnect
the power to the tested motor. Adjust the power supply voltage (or excitation
current) of the dynamometer to make the speed approximately 1/3 of the
intermediate speed. Then increase the power supply voltage of the motor to the
rated value and then turn it on. Quickly adjust the power supply voltage (or
excitation current) of the dynamometer until the dynamometer reading of the
accelerating dynamometer shows the minimum value. Read this value.
9.4.4 Conversion of minimum torque value
The minimum torque is converted according to formula (45):
9.8 Determination of vibration
The determination of motor vibration is carried out according to the provisions
of JB/T 10490.
9.9 Electric strength test
9.9.1 General test requirements
Before the test, it shall determine the insulation resistance of the winding. If it is
necessary to carry out over-speed test, short-term over-torque test or
accidental over-current test, this test shall be carried out after these tests. If a
temperature rise test is required, it shall be performed immediately after the
temperature rise test.
The test shall be carried out when the motor is stationary.
The test voltage is applied between the tested winding and the casing and
between the windings. For interconnected multiphase windings, if the beginning
and end of each phase are not led out separately, it can be tested as a separate
circuit.
9.9.2 Test voltage
The frequency of the test voltage is 50Hz. The waveform is an actual sine wave.
The capacity of the test equipment is not less than 0.5kVA. The test voltage
(effective value) is 1000V+2Urms,max. But the minimum is 1500V. For insulated
windings of motors with rated voltages below 100V, the test voltage (effective
value) is 500V+2Urms,max. Urms,max is the maximum effective value of operating
voltage.
9.9.3 Trip current
No breakdown shall occur in the electric strength test. When the current
exceeds 10mA in the test circuit, it is assumed that breakdown has occurred.
For electric strength test after damp heat test, when the current exceeds 30mA
in the test circuit, it is assumed that breakdown has occurred.
NOTE: A current sensor is installed in the test circuit, which trips when the current exceeds
the limit.
9.9.4 Test time
During the test, the applied voltage shall not exceed half of the full value of the
test voltage. Gradually increase to the full value of the test voltage. The time for
the test voltage to increase from half value to full value shall not be less than
10s. The full voltage test time shall last for 1 min. When performing inspection
segments at an angle of 180 degrees. The test peak voltage of the motor
with a rated voltage of 220V is not less than 1100V. The peak value of the
impulse voltage test of other rated voltage motors is determined by 5 times
UN (UN is the rated voltage of the motor), but the minimum is 500V.
The test method of the impact test of the motor is carried out according to
GB/T 22719.1.
b) Short-term voltage increase test:
The test motor runs at no load at 130% rated voltage. Last 3min (capacitor
running motor is 1min). During the test, the power frequency can be
increased to 110% of the rated value (except for capacitor-operated motors).
But it shall not exceed the speed specified in the overspeed test.
During the test, observe whether the motor has a breakdown such as smoke.
9.12 Leakage current test at working temperature
The motor is powered by 1.06 times the rated voltage. Operate under rated load
or actual load conditions.
If the motor is equipped with a radio interference filter, it shall be disconnected
before the test.
The leakage current is measured by the measurement network described in
Figure 4 in GB/T 12113-2003. The measurement is carried out between any
pole of the power supply and the accessible metal parts connec......
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Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
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