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GB/T 12785-2014 (GB/T12785-2014)

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GB/T 12785-2014: PDF in English (GBT 12785-2014)
GB/T 12785-2014
ICS 65.060.35
B 91
Replacing GB/T 12785-2002
Test methods for submersible motor-pumps
ISSUED ON: JULY 24, 2014
Issued by: General Administration of Quality Supervision, Inspection and
Quarantine of PRC;
Standardization Administration of PRC.
Table of Contents
Foreword ... 3 
1 Scope ... 5 
2 Normative references ... 5 
3 Test and acceptance criteria ... 6 
4 Parameter measurement ... 21 
5 Test preparation ... 24 
6 No-load test of motor ... 27 
7 Thermal test of motor ... 32 
8 Load test of motor and performance test of pump ... 37 
9 Complete set test of unit ... 60 
10 Locked-rotor test of motor ... 64 
11 Determination of the maximum torque of motor ... 68 
12 Determination of the minimum torque of motor ... 71 
13 Withstand voltage test of motor ... 71 
14 Inter-turn insulation test of motor windings ... 73 
15 Measurement of motor noise ... 73 
16 Vibration measurement of motor ... 73 
17 Determination of axial force of submersible pump for well ... 74 
18 Other tests ... 76 
Appendix A (Informative) Calibration time interval for instruments ... 78 
Appendix B (Normative) Evaluation of measurement uncertainty ... 79 
Appendix C (Informative) Quantity, symbol, unit ... 112 
Appendix D (Informative) Converted to SI units ... 116 
References ... 118 
Test methods for submersible motor-pumps
1 Scope
This standard specifies the performance test and acceptance (or assessment)
methods of submersible motor-pumps.
This standard applies to all types of submersible motor-pumps (hereinafter
referred to as "motor-pumps"), including the test of all types of submersible
motors and submersible pumps.
2 Normative references
The following documents are essential to the application of this document. For
the dated documents, only the versions with the dates indicated are applicable
to this document; for the undated documents, only the latest version (including
all the amendments) is applicable to this standard.
GB 755-2008 Rotating electrical machines - Rating and performance
GB/T 1032 Test procedures for three-phase induction motors
GB 1971 Rotating electrical machines - Terminal markings and direction of
GB/T 3214 Methods for measurement of capacity of pump
GB/T 3216 Rotodynamic pumps - Hydraulic performance acceptance tests
- Grades 1, 2 and 3
GB/T 9651 Test procedures for single-phase induction motor
GB/T 10068 Mechanical vibration of certain machines with shaft heights 56
mm and higher - Measurement, evaluation and limits of vibration severity
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 10069.3 Measurement of airborne noise emitted by rotating electrical
machines and the noise limits - Part 3: Noise limits
GB/T 22714 Test specifications of interturn insulation of form-wound winding
for AC low-voltage electrical machines
GB/T 22715 Impulse voltage withstand levels of form-wound stator coils for
rotating a. c. machines
GB/T 22719.1 Interturn insulation of random-wound winding for AC low-
voltage electrical machines - Part 1: Test methods
GB/T 22719.2 Interturn insulation of random-wound winding for AC low-
voltage electrical machines - Part 2: Test limits
3 Test and acceptance criteria
3.1 Guarantee
3.1.1 Guaranteed points
The guaranteed point of the pump shall be determined by the guaranteed flow
QG and the guaranteed head HG. The guaranteed point of the motor is
determined by the motor's nominal frequency fN, nominal voltage UN, nominal
power PN. The guaranteed value is the parameter value, that the motor-pump
shall guarantee, at the guaranteed point, which can be the standard specified
value, the design value or the agreed value during the acceptance test.
Note: The guaranteed points can be referred to as guaranteed, specified,
designed (or nominal), according to different occasions where the provisions
are used.
3.1.2 Guaranteed conditions
Unless otherwise specified, the acceptance test shall comply with the following
guaranteed conditions:
a) It shall use the test liquid, which is specified in 3.3.1, on a test bench,
which meets the methods, test devices, test conditions, which are
specified in this standard.
b) The performance of the pump, which shall be guaranteed, refers to the
performance between the pump inlet and outlet flanges. The pipeline and
accessories, on the outlet side of the pump, are not within the scope of
the guarantee.
c) The performance of the motor, which shall be guaranteed, refers to the
performance of the motor, which contains lead cable within 5 m. The
change in motor performance, which is caused by more than 5 m, is not
within the scope of the guarantee.
The test bench shall be provided by the manufacturer, OR it may be provided
The acceptance test is carried out, with the participation of the buyer’s
representative. The test items shall be negotiated by both parties to the contract.
The acceptance result shall be signed by the buyer’s witness.
3.2.3 Supervised spot check test
It is the random inspection test of quality, which is conducted by product quality
supervision and inspection agencies, as authorized by the competent
government departments at all levels of the country. The test content and items
shall be in accordance with the relevant product standards AND the relevant
documents of the product quality supervision and inspection agency. The test
shall comply with the requirements of this standard, be carried out on a certified
third-party's test bench OR a test bench of a manufacturer, which is approved
by the quality inspection agency.
3.3 Test conditions
3.3.1 Test liquid
The test medium shall be clean cold water OR a liquid, which has the same
chemical and physical properties as clean cold water. The characteristics of
"clean cold water" shall meet the requirements of GB/T 3216.
3.3.2 Test power supply
The test power supply shall meet the requirements of GB/T 1032.
3.3.3 Length of lead cable of test motor-pump
Unless otherwise specified, the cable length of the test motor-pump shall not
exceed 5 m.
3.3.4 Submerged depth of test motor-pump
The test shall be carried out with the motor-pump submerged in water. For
submersible motor-pumps, which are used in high-head wells, the pump head
can be partially submerged; the submerged depth shall ensure that cavitation
does not occur, during the test of the motor-pump.
3.3.5 Stability during the test Operational stability Concepts related to operational stability
The following concepts are involved, in determining whether the operation is
a) Signal average - Usually the measured signal has randomness. The signal
average is one of the statistical characteristics of random signals, which
is represented by the arithmetic average of n repeated measurements, in
an observation period T. The observation period T shall be long enough.
When determining T, it shall consider the longest response time of each
instrument, in the measurement system AND whether it fully reflects the
change characteristics of the measured value.
b) Fluctuations - The periodic or random changes of the signal, which is
output by the measurement system, AND the physical quantities, which
are derived from it around the average value over time, are called
fluctuations. If the measurement signal fluctuates greatly, due to the
structure or operation of the pump, it may use a buffer or damper, that can
reduce the fluctuation to the value range, which is given in Table 1, in the
measuring instrument or its connecting pipeline. However, it shall be noted
that the measures taken cannot affect the "distortion" of the average value
of the readings; it shall provide a fluctuation integral, within at least one
complete fluctuation cycle. The reduction of the fluctuation range by the
buffer shall be bidirectional symmetrical and linear.
c) Variation - The change in the average value of the output signal of the
measurement system and its derived physical quantity.
d) Reading - The visible observation value, which can be recorded by the
output signal of the measuring system.
1) "Quasi-instantaneous" reading: The value, which is read in the shortest
possible time (but not shorter than the response time of the
measurement system).
2) "Average reading" of the signal: The average value of the signal, which
is directly given by a measuring instrument with integral function.
e) Reading group - The group of n “quasi-instantaneous” readings, which is
read during the observation period T. It can be used for statistical analysis
and calculation of data (such as the calculation of average, variance,
standard deviation).
Compared with the change of the average value, the fluctuation is fast, whilst
the change of the average value is slower. According to the change of the
average value, it can be judged whether the operation is stable or unstable. Allowable reading fluctuation range
Table 1 shows the allowable fluctuation range of each measured value, which
is expressed as a percentage of the average value of the observed quantity.
shall not be less than 0.2.
c) The accuracy level of the power transmitter shall not be lower than 0.5.
d) The accuracy level of the torque measuring instrument shall not be lower
than 0.5; the accuracy level of the dynamometer shall not be lower than
e) The maximum allowable error of the rotational speed measuring
instrument is ±0.1%; the accuracy level of the frequency meter shall not
be lower than 0.1.
f) The accuracy level of turbine or electromagnetic flow transmitter shall not
be lower than level 1; other flow measuring instruments shall comply with
GB/T 3214.
g) The accuracy level of the spring pressure gauge shall not be lower than
0.4. It may also use the digital measuring instruments (including pressure
transmitters), which have equivalent accuracy.
h) The maximum allowable error of the temperature measuring instrument is
±1 °C.
i) When the automatic test system is used, the measurement uncertainty,
which is caused by the measurement instruments of each parameter
(including the secondary measurement instrument and the primary sensor
or transmitter), shall not exceed the provisions of Table 4.
For all other measuring instruments and measurement methods, which have
been calibrated or subject to uncertainty evaluation in accordance with
Appendix B, to prove that the uncertainty caused by the parameter measuring
instrument (referred to as the system uncertainty), does not exceed the range
specified in Table 4, THEN they can be used. Selection and use of measuring instruments Pointer instrument
When choosing a pointer type electrical measuring instrument, the measured
value shall be within 20% ~ 95% of the instrument range. When using the two-
wattmeter method to measure three-phase power, the measured voltage and
current values shall be made not less than 20% of the voltage range and current
range, respectively, of the wattmeter.
When using a spring pressure gauge, the appropriate measuring range shall
be selected, according to the prescribed head of the pump. The indicator value
of the pointer shall be more than 1/3 of the pressure measuring range. The
L - The distance from the pressure measuring hole to the pump outlet flange,
in millimeters (mm);
Dj - The diameter of the wellbore, in millimeters (mm);
Dd - The diameter of the submersible motor, in millimeters (mm).
4.4 Electricity measurement
4.4.1 Effective value
Unless otherwise specified, all voltage and current measurements are effective
values (rms).
4.4.2 Voltage measurement
The terminal voltage shall be measured from the cable end, which is lead out
from the motor. If it is not allowed for measurement on site, it shall calculate the
error caused by this AND the reading shall be corrected. When measuring the
three-phase voltage, take the arithmetic average of the three-phase voltage, to
calculate the motor performance.
For motors of 750 W and below, except for the locked-rotor test, the voltmeter
shall be connected to the lead-out cable end of the motor, during measurement;
the voltage shall be adjusted to the required value, THEN, read the voltage
value at this time. Quickly switch the voltmeter to the power supply terminal
AND keep the power supply voltage unchanged; then read the values of other
meters. Under the nominal voltage during the no-load test AND under the
nominal load during the load test, when the difference, BETWEEN the voltage
of the power supply terminal AND the voltage of the motor terminal, is less than
1% of the motor's terminal voltage, the voltmeter can be fixed at the power
supply terminal for measurement.
4.4.3 Current measurement
For three-phase motors, it shall measure the line current of each phase of the
motor, at the same time. Use the arithmetic mean of the three-phase line
currents, to calculate the performance of the motor. For single-phase motors
operating with dual windings, it shall measure the main winding current, the
secondary winding current, the total current, at the same time.
4.4.4 Power measurement
For three-phase motors, the input power shall be measured by the two-watt
meter method or the three-watt meter method. If it needs to obtain more
accurate power measurement values, it may modify it, according to GB/T 1032.
4.5 Measurement of speed or slip
4.5.1 Measuring method of speed or slip
For the measurement of slip or speed, it preferentially adopts the induction coil
method. It may also use the other methods; however, the speed sensing
element used shall not significantly increase the power consumption OR affect
the suction conditions of the pump inlet.
For motor-pumps with special structures, when conventional speed
measurement methods cannot be used to measure the speed or slip of the
motor-pump, such as a built-in submersible motor-pump, it may use the
vibration speed measurement method.
4.5.2 Induction coil method
In the induction coil method, a multi-turn coil, which has an iron core, is sealed
and tightly attached to the upper or lower part of the motor case under test
(equivalent to the upper and lower extension parts of the motor winding). The
coil is connected with a magnetoelectric galvanometer OR a cathode
oscilloscope OR a digital slip meter. When using a galvanometer or a cathode
oscilloscope, determine the number of galvanometer's light spot swings or the
full swing of the oscilloscope waveform, the required time, the power frequency,
during the test. The digital slip meter can measure the frequency of the power
supply and the slip (Hz) of the motor, at the same time, thereby obtaining the
speed of the motor.
4.5.3 Vibration speed measurement method
The vibration speed measurement method is to place the acceleration sensor
on the motor-pump or test pipeline; its direction should point to the axis of the
motor rotation AND perpendicular to the axis. The speed is measured by
spectrum analysis of the vibration signal of the motor-pump, which is output by
the acceleration sensor.
4.6 Measurement of DC resistance
The DC resistance between the lead-out cable terminals, from the two phases
of the winding cables (hereinafter referred to as the terminal resistance), is
measured by a bridge. When the resistance is 1 Ω and below, it shall be
measured by a double-arm bridge. When using automatic detection devices or
digital micro-ohmmeters and other instruments, to measure the winding
resistance, the test current, through the tested winding, shall not exceed 10%
of its current in normal operation; the power-on time shall not exceed 1 min. If
the resistance is less than 0.01 Ω, the current, through the winding under test,
8 Load test of motor and performance test of pump
8.1 General requirements
8.1.1 For the motor load test, it shall measure the motor input power P1, load
current I1, efficiency ηm, power factor cosφ, slip rate s (or speed n), output power
P2, at the nominal voltage, nominal frequency, specified temperature.
8.1.2 For the pump performance test, it shall measure the total pump head H
(or full pressure pi), flow Q, shaft power Pt, pump efficiency ηp, under nominal
voltage, nominal speed or nominal frequency.
8.1.3 The method of using the pump as the load shall be preferred. The two
tests can be completed at the same time, in one test process, by adjusting the
valve opening to change the working condition of the pump AND the output
power of the motor, at the same time. The dynamometer can also be used, to
do the load test of the motor, but it shall be equipped with a special test device.
Submerge the tested motor under water. Make the shaft's extension end be
exposed above the surface of the water. Use related measuring equipment and
instruments, to connect with the motor's shaft extension end for the test. When
limited by the shaft power of the test equipment or pump, under the nominal
voltage, it cannot get the satisfactory result of the motor, through the test, at the
nominal power, THEN, it is allowed to use the circle diagram calculation method,
to find the parameters of the nominal load point.
8.1.4 For the calculation and processing of test results, motor load performance
and pump performance shall be carried out separately. The performance of the
motor shall be converted to the specified temperature of the motor; the
performance of the pump shall be converted to the nominal speed. Unless
otherwise specified for vane pumps, the test speed can be within the range of
50% ~ 120% of the nominal speed. When the change of the test speed is within
±20% of the nominal speed, the change in pump efficiency can be ignored.
8.2 Test method
8.2.1 Test method with pump as motor load
Motor load test and pump performance test shall be carried out, at nominal
voltage and nominal frequency. Loss analysis and recommended load stray
loss methods are used, to determine motor efficiency and pump shaft power. If
the maximum current value of the motor, that can be achieved during the test,
does not reach the nominal current value, if the motor-pump structure allows, it
may increase the motor output power and current, by reversing the motor, to
meet the test requirements. In the case that the motor-pump is not allowed to
reverse OR reversing cannot reach the nominal current value, it may replace a
8.4.1 State of motor-pump during the test
The motor-pump shall be submerged in the water. Under the nominal frequency,
nominal voltage, nominal flow of the pump, pre-operate it for 1 h ~ 1.5 h,
according to different structure and power, respectively, until it reaches the
stable operation conditions, which is specified in Table 1, Table 2 or Table 3,
meanwhile the motor achieves thermal stability. If the load test and pump
performance test are carried out, immediately after the thermal test, the pre-
operation time can be appropriately shortened. The test shall be carried out,
under the condition that the performance of the pump is not affected by
8.4.2 Test procedure
The test shall start from the point of minimum power. For centrifugal pumps, it
generally starts from zero flow AND gradually increases to more than 140% of
the flow guaranteed point OR the valve is fully opened. For mixed flow pumps,
axial flow pumps, vortex pumps, it shall start from the full-open state of the valve,
gradually reduces to less than 60% of the flow guaranteed point. It shall take
13 ~ 15 different flow points in between them. The flow points taken shall
include flow guaranteed points QG, 95%QG, 105%QG, small flow point Qmin,
large flow point Qmax and nominal current point of the pump working range. For
centrifugal pumps, it shall also include the zero flow point.
For screw pumps, it generally starts from the zero pressure point (valve fully
open), gradually increases to near the pressure guaranteed point. It shall take
10 ~ 13 different flow points in between them. The flow points taken shall
include flow guaranteed points pG, zero pressure point pmin, 50%pG, 75%pG,
95%pG, nominal current point. When the flow control valve is fully open AND
the pump's outlet pressure does not exceed 0.05 MPa, the outlet pressure is
regarded as zero pressure.
When the maximum current value of the motor, that can be measured in the
above test process, does not reach the nominal current, if the motor-pump
allows, it shall make measurement for another 2 ~ 3 points, when the pump is
reversed after the resistance is measured, so that the test current reaches 1.25
times the nominal current. At this time, the flow and pressure do not need to be
There shall be a certain time interval for each point of measurement, to ensure
that the operating point reaches a stable state. At each operating point, the
following parameters shall be measured, at the same time, at nominal voltage
and nominal frequency:
a) For three-phase motor-pumps: Read the three-phase current, input power,
power frequency, slip (or speed), outlet pressure, flow value;
Appendix B
Evaluation of measurement uncertainty
B.1 General
For the evaluation of measurement uncertainty of the motor-pump test, unless
otherwise specified, it only evaluates the uncertainty of the measurement
results of the flow, head, speed, pump shaft power, efficiency in the pump
performance test. The measurement uncertainty of the pump efficiency is used
as the evaluation result of the measurement uncertainty of the test system.
For the evaluation of measurement uncertainty of the motor-pump test, it is
formulated, based on the principles, methods and procedures for evaluating
and expressing the measurement uncertainty, which is given in JJF 1059.1-
2012. It is the specific application of the basic theory of experimental error, in
pump testing technology.
B.2 Sources of measurement error and uncertainty in the test
The main sources of measurement error and measurement uncertainty, in the
motor-pump test, are:
a) The maximum allowable error and uncertainty of measuring instruments
and sensors;
b) The fluctuation and change of parameters, which is caused by the
unstable liquid flow, due to the non-standardization or imperfection of the
design, manufacturing, installation of the test device;
c) Random changes in the test environment and conditions (such as power
supply frequency, voltage fluctuations, room temperature, water
temperature, water level changes, etc.);
d) Instability during test operation;
e) An artificial deviation in the readings of pointer type instruments (such as
spring pressure gauges);
f) Additional errors, which are caused when the use conditions of the
instrument exceed the normal use range;
g) Approximations and assumptions of measurement methods and
measurement procedures;
(Above excerpt was released on 2021-11-05, modified on 2021-11-05, translated/reviewed by: Wayne Zheng et al.)
Source: https://www.chinesestandard.net/PDF.aspx/GBT12785-2014