JB/T 6744-1993 General technical requirements for dynamometers for testing small power motors
Some standard content:
Mechanical Industry Standard of the People's Republic of China
General Technical Conditions for Dynamometers for Testing Small Power Motors Subject Content and Scope of Application
JB/T6744—93
This standard specifies the measurement scope, technical requirements, test methods, inspection rules, completeness, marking, packaging, transportation and historical records of dynamometers for testing small power motors.
This standard applies to asynchronous dynamometers, synchronous dynamometers, permanent magnet dynamometers, induction dynamometers, hysteresis dynamometers, magnetic powder dynamometers, eddy current dynamometers and DC dynamometers.
2 Reference standards
GB5171
General technical conditions for small power motors
JJG1001
Verification procedures for measuring instruments Common metrological terms and definitions GB12665 Requirements for damp heat test of motors under general environmental conditions GB1032
3 Terms
Test methods for three-phase asynchronous motors
Packaging, storage and transportation pictorial symbols
Magnetic code verification procedures
Terms and definitions specific to this standard are as follows:
3.1 Dynamometer
A measuring device that can generate braking torque and has a torque and speed indicator. 3.2 Reference error
The ratio of the absolute error to the upper limit of the measuring range or the measuring range, expressed as a percentage. 3.3 Sensitivity
The minimum change in the measured quantity that causes a detectable change in the indication of the measuring instrument (meter), also known as sensitivity. 3.4 Limit torque
refers to the maximum value of the short-term overload torque that the dynamometer can withstand. 3.5 Maximum recommended torque
refers to the maximum torque at which the dynamometer can still operate for a long time at the limit speed without exceeding the allowable temperature rise. 3.6 Limit speed
refers to the maximum speed at which the dynamometer can operate reliably for a long time without causing harmful deformation. 4 Measuring range of dynamometer
4.1 Measuring range of dynamometer under continuous working system S1 On the rectangular coordinate plane with torque as the vertical coordinate and speed as the horizontal coordinate, the rectangular area surrounded by four straight lines of maximum recommended torque, minimum measurable torque, limit speed and minimum speed range is the measuring range. 4.2 The measurement range of the dynamometer under the short-time working system S2 In the rectangular coordinate system with power, time, torque and speed as coordinates, the multi-dimensional area surrounded by the power-time curve determined by the allowable critical temperature rise and the limit torque, limit speed and each coordinate plane is the measurement range. 5 Technical requirements 5.1 Braking torque, that is, the maximum recommended torque of the dynamometer of the S1 working system and the limit torque of the dynamometer of the S2 working system, are selected according to the following provisions: 40, 100, 250, 600, 1500, 4000, 10000, 25000, 60000 mN·m. 5.2 The limit speed is selected according to the following provisions;
3000, 4000, 9000, 15000, 21000, 30000r/min5.3 The minimum torque that can be measured by the dynamometer is 5% of the maximum recommended torque (or limit torque). 5.4 The minimum speed that can be measured by the dynamometer is 5% of the limit speed. 5.5 Error of dynamometer
5.5.1 The environmental conditions for measuring error are indoor temperature of 10-30℃, relative humidity less than 80%, quiet environment, and no perceptible mechanical vibration and impact.
5.5.2 The torque measurement error (see Appendix A) is within the full range of measurement. For braking torques of 600mN·m and above, the reference error is less than ±0.5%, and for braking torques of 250mN·m and below, the reference error is less than ±1.0%. Note: The full scale of torque is the maximum recommended torque for the dynamometer of S1 working system and the limit torque for S2 working system. 5.5.3 The error of speed measurement is less than ±0.1% of the limit speed. 5.6 The torque sensitive valve of the dynamometer is 50% of its reference error. 5.7 When the altitude does not exceed 1000m and the ambient air temperature does not exceed 40℃, when the dynamometer is used within its measurement range, the temperature rise and temperature limit of each heating part shall not exceed the provisions of the following table. Measuring part
S1 working system
S2 working system
Photometer method
Resistance method
Thermometer method
Resistance method
Inner and outer bearings
5.8 The insulation resistance of the dynamometer winding to the casing and between the windings shall not be less than 1.0MQ in the hot state or not less than 20M in the normal state. 5.9 The dynamometer windings shall be able to withstand a withstand voltage test for 1 minute without flashover or breakdown. The test voltage frequency is 50Hz, the waveform is a real sine wave, and the capacity of the test equipment is not less than 0.5kVA per kilovolt. For the AC windings of the dynamometer, the test voltage (effective value) is 1000V plus twice the rated voltage, and for the DC excitation windings of the dynamometer, the test voltage (effective value) is 500V plus twice the rated voltage.
5.10 The AC windings of the dynamometer shall be subjected to an inter-turn insulation impulse withstand voltage test without breakdown. The impulse test voltage (peak value) is 1.4 times the withstand voltage test value, and the wavefront coefficient is 0.5μs.
5.11 The dynamometer shall be able to withstand an over-torque test of 1.1 times the limit torque for 15s without harmful deformation in the hot state and with gradually increasing torque.
5.12 Under no-load conditions, the dynamometer should be able to withstand an increase in speed to 1.1 times the maximum recommended speed for 2 minutes without harmful deformation.
5.13 After a 6-day damp heat test, the insulation performance of the dynamometer should meet the following requirements: The insulation resistance of the dynamometer winding to the casing and between the windings should not be less than U/1000Mn. a.
The insulation withstand voltage test of the dynamometer winding to the casing and between the windings should be able to withstand 85% of the test voltage specified in Article 5.9 of this standard for 1 minute without breakdown flashover. 5.14 There should be no obvious spots, wrinkles, bubbles, magnetic damage, cracks and adhered dirt on the surface of the dynamometer. In addition, there should be no looseness or displacement of parts. 96
JB/T6744-93
5.15 If the user uses and stores the dynamometer correctly according to the operating and maintenance instructions, the manufacturer shall ensure that the dynamometer can operate well within one year of use, but no more than two years from the date of shipment from the manufacturer. If the dynamometer is damaged or malfunctions due to poor manufacturing within this specified period, the manufacturer shall repair or replace the dynamometer for the user free of charge. 6 Test method
6.1 Measurement of torque errorbzxZ.net
6.1.1 The torque error of various types of dynamometers shall be measured by a standard dynamometer. The torque error of the standard dynamometer is expressed by the maximum insulation error △sm. The torque full scale Am of the calibrated dynamometer shall comply with the relationship Asm<0.15%
6.1.2 When measuring the error, the calibrated dynamometer and the standard dynamometer are coaxially connected with a coupling, and the concentricity of the connection must be guaranteed. Then, the standard dynamometer is used as the motor and the calibrated dynamometer is used as the load to operate stably at different speeds and torques, and the difference in torque readings between the two is read, which is the absolute value of the torque error of the calibrated dynamometer.
The above-mentioned speed measurement shall not be less than three points, including the limit speed, and the torque measurement shall not be less than five points, including no-load and maximum recommended torque (or limit torque):
6.1.3 For asynchronous or synchronous dynamometers with a lever balance as the force measuring mechanism, the torque error can be determined by self-calibration or calibration according to the procedures specified in the appendix. The dynamometer after the error is determined can be used as a benchmark for the torque error measurement of other dynamometers of equivalent capacity, but its reference error should be guaranteed to be less than 0.15%.
6.2 Measurement of speed error
The tachometer is an external accessory and should be purchased in accordance with the requirements of Article 5.5.3 of this standard. 6.3 Sensitivity threshold check
When the dynamometer is in a stationary state, the lever is kept in a horizontal position, and the torque calibration zero needle points to zero, add weight in any base code disk, and slightly increase the weight from the minimum value of the code. When the pointer has a perceptible deflection, it stops. At this time, the torque value obtained by multiplying the base code mass by the lever arm length is the sensitivity of the dynamometer, which should not exceed the provisions of Article 5.6 of this standard. 6.4 Temperature rise test
6.4.1The temperature rise test is carried out in accordance with Chapter 8 of GB1032. The dynamometer is driven by a DC or excitation motor, or an asynchronous motor with a variable frequency power supply.
6.4.2The braking torque of the dynamometer in S1 working mode is maintained at the maximum recommended torque, and the speed should be the limit speed. It can fluctuate within the range of ±5%, but the product remains unchanged. Continuously operate under this load until the temperature rise of each part of the dynamometer reaches a thermally stable state. Record the temperature of the surrounding medium, the temperature of the dynamometer core and bearings, and the resistance of the winding before and after the test every half an hour to calculate the temperature rise of the winding. 6.4.The braking torque of the 3S2 working mode dynamometer is selected within the range from the limit torque to the minimum measurable torque, and the speed is selected within the range from the limit speed to the minimum measurable speed. The torque M, speed n are used to obtain the power Pi, and the test is carried out by maintaining P until the temperature rise of each part of the dynamometer reaches or approaches the temperature rise limit. The test duration ti corresponding to P is recorded, and the energy is cut off and cooled to room temperature. M2 and n are reselected to obtain Ps, and P is maintained for further testing, and tz is recorded. Five groups of M and n are selected for testing, and five groups of P-t values are obtained. Thus, the critical Pt curve of the S2 working mode dynamometer can be obtained,
. In order to check whether the temperature rise of the S2 working mode dynamometer is qualified, the corresponding Piti value can be found at any point according to the P-t curve provided by the manufacturing department. P is maintained, and the test duration is t. After that, the energy is cut off and the temperature and temperature rise of each part of the dynamometer are checked. They should not exceed the temperature and temperature rise limits specified in this standard.
6.5 The electrical performance test of the dynamometer 5.85.13 shall be carried out in accordance with the provisions of GB1032. The damp heat test method of the dynamometer shall be carried out in accordance with the provisions of GB12665. 6.6
6.7 The measurement of the minimum torque and minimum speed of the dynamometer shall be determined by the standards of various dynamometers. 7 Inspection rules
Each dynamometer must be inspected and qualified before it can leave the factory, and a product inspection certificate shall be attached. 7.1
JB/T674493
Each dynamometer shall undergo factory inspection, and the inspection items are as follows: 7.2
Appearance quality inspection;
The dynamometer shall swing flexibly, the lever shall be flat and symmetrical, and the magnetic code shall be verified according to the JJG99 regulations; Determination of insulation resistance between the winding and the casing and between the windings; Determination of DC resistance of the winding under actual cold state; Dielectric strength test;
Turn-to-turn insulation test;
Torque error verification;
Tachometer error assessment,
Sensitivity threshold inspection.
Type inspection shall be carried out when the trial production of new products is completed. The number of type inspection prototypes is 12 sets. The type inspection items are as follows:
All items of factory inspection;
Temperature rise test;
Wet heat test;
Over torque test;
Increase speed test;
Torque minimum value and speed minimum value test. 8 Completeness
Various accessories should be equipped upon delivery, such as keys, couplings, bricks, installation platforms, and tachometers. 8.1
Product certificate and operating and maintenance instructions should be attached upon delivery. 9 Marking, packaging, transportation and storage
The nameplate of each dynamometer must be in a conspicuous position on the dynamometer, and the nameplate material and the data and marking method on the nameplate should ensure that the writing is not easily erased.
The following items should be marked on the dynamometer nameplate: a.
Dynamometer type;
Maximum excitation current;
Maximum recommended torque (S1 duty system) or limit torque (S2 duty system); stator winding reference voltage,
reference frequency;
limit speed;
duty system;
Standard number:
Manufacturer name;
Year, month and day of manufacture.
Note: The marking of items b, d and e can be determined according to the type of dynamometer involved in the hospital, 9.3
The shaft extension of the dynamometer should be temporarily protected by anti-inducing coating and sealing before packaging. The packaging must be firm and reliable. The packaging box should be marked with words such as "Handle with care" and "Avoid moisture". The corresponding drawings should comply with the provisions of GB191. The packaging box should be handled with care during transportation to avoid collision and knocking. It is strictly forbidden to put it together with corrosive items such as acids and alkalis. 9.4 The dynamometer is stored in a clean and well-ventilated warehouse with an ambient air temperature of -5.℃~+40℃ and a relative humidity of no more than 90%. The air must not contain corrosive gases.
A1 Self-calibration method
JB/T6744-93
Appendix A
Correction of torque error of horizontal asynchronous and synchronous dynamometers (supplement)
A1.1 The distance 21 between the two force measuring points of the lever should be measured by a precision length measuring instrument before assembly. If the distance 21 is measured, the distance between the two force measuring points of the lever should be measured by a precision length measuring instrument before assembly. Indicates the nominal distance between the two force measuring points, let |L-=t.
A1.2 After checking and making sure that the pointer points to zero when the lever is in a horizontal state, continue with the following steps. A1.3 Place codes of the same mass on the scale on both sides of the lever. If the pointer still points to zero, continue to add equal amounts of code on both sides until the pointer deviates. The maximum weight of the code added to the scale before the pointer deviates is recorded as P1. A1.4 Gradually and lightly add the base code at one end of the lever balance until the pointer deviates observably, and record the weight of the rank code at this time: repeat the above process at the other end of the balance, and then record the weight of the code. The larger of the two weight values is recorded as P. . A1.5 The dynamometer is operated as a motor at no-load at the maximum limit speed. Lightly place a magnetic code on the balance so that the pointer points to zero, and record the magnetic code quantity; let the dynamometer be at another end. Repeat the above process for one turn, and then record the weight of the weight. The larger of the two weight values is recorded as P:. A1.6 If P is defined as the weight of the balancing weight required to be added to the balance when the maximum load torque is reached (equal to the maximum recommended torque divided by the nominal length of one side of the lever, L), then the upper limit of the absolute error of the dynamometer torque measurement is determined by formula ^1: LP.
A2 Calibration method
）·P,+L·(P+2P。)
..(A1)
This method is applicable to synchronous and asynchronous dynamometers that use the lever-based weight method to measure torque. During measurement, two identical dynamometers are connected with a coupling, one running as a motor and the other running as a generator. The specific method for measuring torque error is as follows;
A2.1 Calibration of dynamometer|| tt||Before connecting two dynamometers with a coupling, each dynamometer must be calibrated separately. Only when the calibration is qualified can the torque error be measured. The calibration method is as follows 1 to 5.
A2.1.1 When the dynamometer lever is horizontal, adjust the pointer to zero and tighten it. A2.1.2 For dynamometers with heavy hammers, the heavy hammer must be removed, leaving only the heavy hammer rod, and two magnetic code disks are hung (without the base code). A2.1.3 Connect the dynamometer to a three-phase 50Hz power supply, and adjust the voltage to start the dynamometer so that it runs without load at a voltage not less than 0.5 times the rated voltage, and adjust the position of the balance block so that the pointer points to zero. A2.1.4 Move the lever by hand to make the pointer deflect 0.51% of the full-scale torque value on the dial or scale (generally, the dynamometer deflects about 5 grids). After letting go, the pointer should stop at zero after reciprocating swing. If the pointer does not stop at zero, the torque value of the position pointed to should be measured. Its value should not be greater than 0.05% of the full-scale torque value. If it is greater than the above value, the dynamometer is considered to have failed the calibration. A2.1.5 After the calibration of Article 4 above is qualified, put equal weights in the two base plates of the dynamometer. The torque generated by the product of the base and the lever arm length should be 60% to 80% of the full-scale torque value. See if the pointer points to zero at this time. If it points to zero, the lever arm length error has been eliminated and the calibration is qualified. If it does not point to zero, the torque value of the position pointed to by the pointer should be measured, and its value should not be greater than 0.05% of the full-scale torque value. If it is greater than the above value, the screws for fixing the lever should be loosened, the ends of the lever should be gently beaten, and the arm lengths of the two ends of the lever should be adjusted so that the pointer points to zero. After removing the code, the pointer also points to zero. If it does not point to zero, the position of the lever and the balance block should be adjusted repeatedly. Until the pointers on the disk point to zero regardless of whether the code is placed or not. Or the torque value at the position indicated by the pointer is not greater than 0.05% of the full-scale torque. At this time, the dynamometer is also calibrated. If the above requirements are still not met after repeated adjustments, the dynamometer is considered to be uncalibrated. Note: ① The machining tolerance value of the lever arm length of the drum calibration dynamometer should not be greater than 0.05% of the nominal size of the lever arm length. ② The base code used for the calibration dynamometer should be a 4th grade or above balance magnetic code that has passed the inspection. Dynamometer torque error measurement
JB/T 674493
A2.2.1 Connect two identical calibrated dynamometers with a coupling to form a unit. The installation work should ensure that the two couplings and the dynamometer axis are concentric as much as possible to eliminate the measurement error caused by the coupling resistance torque. A2.2.2 Connect one dynamometer to a 50Hz rated power supply or variable frequency power supply and operate it as a motor. The other dynamometer is connected to a load resistor (when testing a synchronous dynamometer) or a variable power supply (when testing an asynchronous dynamometer) to operate as a generator. Adjust the excitation current and load resistor of the synchronous dynamometer or the power supply frequency of the asynchronous dynamometer so that the measured torque and speed reach the required values (generally, the torque values measured by the two dynamometers are basically equal, and the one operating as a motor should be slightly larger). Then fine-tune the base weight of one dynamometer so that the pointers of both dynamometers point to zero, and read the torque values measured by the two dynamometers at the same time. At this time, the absolute value of the torque measurement error of each dynamometer △T (mN·m) should comply with the provisions of formula A2. AT≤T,-T
Where: T,- — Torque value measured by the dynamometer when the motor is running, mN·m, T, - — Torque value measured by the dynamometer when the generator is running, mN·m. Additional remarks:
This standard is proposed by the Small Power Motor Technical Committee of the National Technical Committee for Standardization of Rotating Electrical Machines. This standard is under the jurisdiction of the Guangzhou Electric Science Research Institute. This standard was drafted by the Guangzhou Electric Science Research Institute. The main drafters of this standard are Xu Huizhen and He Xiangji. 100
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