Household Appliance Compressor Motor Testing Equipment

The motor characteristic testing system is suitable for measuring single-phase and three-phase AC variable-frequency motors. It supports comprehensive testing, fixed-point testing, and manual testing to obtain various motor parameters, including torque, speed, output power, voltage, current, input power, power factor, rotation direction, and efficiency. It boasts high reliability and good repeatability. The testing range includes a maximum power of 30KW, maximum torque of 100N·m, maximum rotational speed of 25,000rpm, and a testing accuracy of ±0.5%.

Test Items:

• General parameter measurements
• Load characteristic tests
• Torque-speed characteristics and efficiency
• Critical characteristic parameter measurements
• Response time testing
• Locked-rotor testing
• Free curve loading

4.4 Reference Standards:

The motor testing methods of this system strictly comply with relevant national standards. The standards involved in this solution are as follows:

• GB-T 1032-2012 Test Methods for Three-Phase Induction Motors
• GB/T 1032-2012 Test Methods for Three-Phase Induction Motors
• GB/T 1029-2005 Test Methods for Three-Phase Synchronous Motors
• GB/T 755-2008 Ratings and Performance of Rotating Electrical Machines
• GB/T 21663-2008 Technical Requirements for Small-Capacity Energy-Saving and Environmentally Friendly Salient-Pole Synchronous Generators
• JB/T 1093-2010 Basic Test Methods for Traction Motors

4.5 Usage Environment:

4.5.1 Testing Environment Requirements:

1. Location: The placement of the testing system must have a load-bearing capacity of at least 0.5 tons per square meter.
2. Ambient Temperature: Maximum temperature must not exceed 35°C; minimum must not go below 15°C.
3. Humidity: 25%–75% RH, with no condensation.
4. Atmospheric Pressure: 86kPa–106kPa.
5. Pollution: The air should not contain excessive dust, acid, salt, or corrosive and explosive gases.

4.6 Product Appearance:

The test bench consists of the motor under test, drive system, dynamometer, and fixtures. The image below represents the standard vertical cabinet paired with a testing steel bench.

The motor testing functions include assessing the basic operational conditions of the motor. It can also simulate operational conditions at various speeds, enabling users to predict potential scenarios during actual applications. For instance, it can simulate motor operation under load or in a constant torque state, showing the corresponding changes between torque and speed.

5.1 General Parameter Measurements:

• Electrical Parameters: Voltage, current, input power, power factor, frequency, etc.
• Mechanical Parameters: Torque, speed, output power, rotation direction, etc.
• Other Parameters: Motor efficiency.

5.2 Load Characteristic Testing:

• Function Introduction: When the motor drive system operates with an actual load, the torque it experiences is not constant. To test such scenarios, torque is applied to the motor under test to simulate on-site conditions.
• Testing Purpose: This test primarily examines the motor’s performance under varying loads.
• Testing Method: Load is controlled via software, and different loading points are set. The torque and speed values measured by the dynamometer are transmitted to the controller and uploaded to the industrial control computer for processing. Results are displayed on the software interface using curves and numerical formats to describe the motor’s condition.

5.3 Torque-Speed Characteristics and Efficiency:

Torque-speed curves are automatically tested and plotted by the software on the industrial control computer. Measurement of drive motors, drivers, and system efficiency mainly relies on high-precision power analyzers and imported dynamometers. Test results are automatically generated in report form. The methods and standards are detailed below:

1. Torque-Speed Curve:
   • Testing Purpose: To map the characteristic curve between speed and torque.
   • Testing Method: Use the dynamometer as the load for the motor under test while keeping the motor in a heated operating state. The controller’s DC bus voltage is set to the rated voltage, and testing can be conducted under either actual cold or heated conditions. The controller’s DC bus voltage can be adjusted to maximum, minimum, rated, or other operational voltages (default is rated voltage in this system). The dynamometer system loads the motor from no load to locked rotor, generating a full curve.

1. a) Speed Testing Points: – At least 10 speed points are selected within the motor’s operating speed range. – The lowest speed point should be no greater than 10% of the maximum operating speed, and the interval between adjacent points should not exceed 10% of the maximum speed. – Necessary characteristic points should be included, such as: 1. Rated operating speed point 2. Maximum operating speed point 3. Lowest speed corresponding to continuous power 4. User-specified special speed points
2. b) Torque Testing Points: – For each speed point, at least 10 torque points are selected during motoring or regenerating operation. For high-speed conditions, the number of torque points can be reduced but not fewer than five. – Necessary characteristic points should be included, such as: 1. Points corresponding to continuous torque value 2. Points corresponding to peak torque (or maximum torque) 3. Points on the continuous power curve 4. Points on the peak power (or maximum power) curve 5. User-specified special torque points

• AC induction motor T/N characteristic curves.

5.4 Measurement of Critical Characteristic Parameters:

This phase verifies whether the manufacturer’s specified parameters meet the requirements. By entering the continuous torque, continuous power, peak torque, and peak power into the industrial control computer’s software, the system automatically measures the results, evaluates compliance, and outputs a detailed report.

1. Continuous Torque Measurement:
   • Testing Purpose: To confirm that the motor’s continuous torque complies with the technical specifications of the product.
   • Testing Method: The dynamometer applies load as per the technical specifications, allowing the motor to operate at the designated speed and torque for an extended period. The motor’s insulation class and temperature rise are monitored to ensure they remain within specified limits.
2. Continuous Power Measurement:
   • Testing Purpose: To confirm that the motor’s continuous power complies with the technical specifications of the product.
   • Testing Method: Using the continuous torque and corresponding speed obtained as described, the specified continuous power can be calculated using the following formula.
   • Pm = T x n / 9550

     Pm — Continuous power at the shaft end of the drive motor, measured in kilowatts (kW).

     Peak Torque Measurement:

     1. Testing Purpose: To verify that the drive motor’s peak torque meets the specifications outlined in the product’s technical documentation.

     2. Testing Method: Using the manufacturer’s provided reference for peak torque during operation (either 1 minute or 10 seconds of continuous operation), experiments are conducted for measurement. As a special case of peak torque, the maximum torque at each speed operating point can be tested. During the experiment, the testing duration at the maximum torque point can be very short, typically less than 10 seconds (this can be set through industrial control software). Based on the experimental data, a speed-to-maximum torque curve for the drive motor system is plotted.     
        Peak Torque Measurement:

     • Testing Purpose: To verify that the drive motor’s peak power meets the specifications outlined in the product’s technical documentation.

     • Testing Method: By obtaining the peak torque and the corresponding operating speed as described, the specified continuous power can be calculated using the following formula:

     • Pc= T x n / 9550
       Pc — Peak power at the shaft end of the drive motor, measured in kilowatts (kW).

   • 5.5 Locked-Rotor Testing:

     • Testing Purpose: The locked-rotor test measures the locked-rotor current (IK) and locked-rotor torque (TK) at rated voltage. It also determines the relationship curves between locked-rotor current, locked-rotor torque, locked-rotor input power, and input voltage, collectively referred to as locked-rotor characteristic curves. By analyzing the magnitude and three-phase balance of the locked-rotor current, it reflects the rationality and quality of the motor’s stator and rotor windings, as well as the magnetic circuit formed by the stator and rotor. This provides actual test data for design and process improvement, as well as assistance in identifying failure causes and determining repair methods for malfunctioning motors.

     • Testing Standards:

       • GB/T 22669-2008 Test Methods for Three-Phase Permanent Magnet Synchronous Motors, Chapter 7: Locked-Rotor Testing

       • GB/T 1032-2012 Test Methods for Three-Phase Induction Motors, Chapter 9: Locked-Rotor Testing

      

     5.6 Free Curve Loading:

     Free curve loading significantly reduces the PID adjustment time during closed-loop load testing. Through open-loop loading and manual testing, it enables the dynamic loading of arbitrary load waveforms, providing users with a realistic simulation of motor operating conditions in actual scenarios.