What are the common electrical faults and solutions for DC motor motor automatic tester?
DC motor motor automatic tester common electrical faults and solutions
First, the power supply failure
1, the power can not be connected
Fault phenomenon:
The test machine is completely unresponsive, the power indicator does not light up, the device can not start.
Cause analysis:
The plug is not plugged in or the socket is damaged, and the power cord may be disconnected.
The power switch of the device is faulty and the internal fuse is blown.
Solution:
First check whether the plug is firmly inserted into the socket, try to replace the socket to test. Check if the power cord is visibly broken, if so, replace the power cord.
Check the connectivity of the power switch, if damaged replace the switch. For the fuse, find the fuse holder and use the same specification fuse for replacement, note that the power supply should be cut off before replacement to prevent electric shock.
2, power fluctuations or instability
Fault phenomenon:
During the operation of the tester, the motor speed is unstable, the test data fluctuates abnormally, and the equipment may restart intermittently or report errors.
Cause analysis:
The external power supply grid is unstable, and the voltage may be too high, too low or fluctuate frequently.
The power module inside the tester is faulty, such as the rectifier, voltage regulator and other components are damaged, and the output voltage cannot be stabilized effectively.
Solution:
Install a voltage regulator or uninterruptible power supply (UPS) to stabilize the input voltage. Use a voltmeter to monitor the input voltage to ensure that it is within the voltage range required by the equipment (usually labeled on the equipment nameplate).
For internal power module failures, open the equipment enclosure (under power failure and operated by a professional) and use a tool such as a multimeter to check whether the output voltage of the rectifier, voltage regulator, and other components is normal. If found damaged components, according to the circuit diagram of the equipment and component specifications for replacement.
Second, the motor drive circuit failure
1, the motor can not start
Fault phenomenon:
The power supply of the test machine is normal, but the motor does not show any sign of starting, and the control software shows that the motor start command has been sent, but the motor does not respond.
Cause analysis:
Motor drive circuit in the power transistor, field effect tube or integrated circuit chip is damaged, can not convert the control signal into sufficient drive current to start the motor.
The connecting wires between the drive circuit and the motor are disconnected, including the winding connecting wires and brush connecting wires.
The control signal cannot be transmitted to the drive circuit normally, which may be due to the communication line failure between the controller and the drive circuit or the output signal failure of the controller itself.
Solution:
Use the diode test gear of the multimeter to check whether the power transistor, field effect tube and other components are normal, and for damaged components, replace them according to the model and specifications of the components. Check the power supply and input/output pin signals of the IC chip, if there is any problem, the chip may need to be replaced.
Check the connecting wires between the motor and the drive circuit, including whether the welding points are firm and whether the wires are broken. If there are any broken wires, re-solder or replace the connecting wires.
Check the communication lines between the controller and the drive circuit to ensure that the signal lines are properly connected and that there are no shorts or breaks. Use an oscilloscope and other equipment to check whether the controller's output signal is normal, if the signal is abnormal, the controller may need to be repaired or replaced.
2, abnormal motor speed
Fault phenomenon:
After the motor is started, the speed does not match the set value, either too high or too low, and can not be effectively adjusted through the control software.
Cause analysis:
Driving circuit in the speed components failure, such as speed potentiometer damage, PWM (Pulse Width Modulation) controller failure.
Changes in the magnetic field strength inside the motor, possibly due to demagnetization of the permanent magnets or damage to the magnetic field regulating components of the stator winding.
Changes in the motor load, such as jamming and increased friction in the mechanical transmission part of the tester, affect the actual speed of the motor.
Solution:
Check whether the resistance value of the speed-regulating potentiometer can be adjusted normally; if it is damaged, replace the potentiometer with the same specification. For the PWM controller, check its input and output signals, use an oscilloscope to observe whether the frequency and duty cycle of the PWM signal meet the requirements, if there is any problem, it may need to be reprogrammed or replaced.
Use a gaussmeter to measure the magnetic field strength inside the motor. If the permanent magnets are demagnetized, it may be necessary to replace the permanent magnet part of the motor. Check the magnetic field regulation components of the stator winding, such as whether the connection of the magnetic field winding is normal or not, and whether the current regulation components are damaged or not.
Check the mechanical transmission part of the tester, including the tension of the belt, the meshing of the gears, and the lubrication of the bearings. Clean up, lubricate or replace the corresponding parts of the parts that appear to be stuck or have increased friction in order to reduce the motor load.
Third, sensor failure
1, speed sensor failure
Failure phenomenon:
The motor speed displayed by the tester does not match the actual speed, the speed data jumps abnormally, or the control software prompts the speed sensor failure.
Cause analysis:
The distance between the probe of the speed sensor and the rotating parts of the motor is not appropriate, may be too close to cause collision damage, or too far away from accurate sensing.
The sensor itself is damaged, the internal sensing elements, circuit components failures, such as Hall component damage, coil breaks, etc..
Problems with the connecting wires between the sensor and the tester's control circuit, such as loose, shorted or broken.
Solution:
Adjust the distance between the speed sensor probe and the rotating parts of the motor, generally according to the installation instructions of the sensor, the distance will be adjusted to the appropriate range, usually in a few millimeters.
Use a multimeter to check the resistance, voltage and other parameters of the sensor to determine whether the internal components of the sensor are damaged. For damaged sensors, replace the sensor with the same model according to the equipment requirements.
Check the connecting wires between the sensor and the control circuit to make sure that they are firmly connected and that there are no loose, short or broken connections. If there is a problem, reconnect or replace the connection line.
2, temperature sensor failure
Fault phenomenon:
The motor temperature displayed by the tester deviates greatly from the actual temperature, or the motor temperature cannot be displayed normally, resulting in the inability to provide effective temperature protection for the motor.
Cause analysis:
The probe of the temperature sensor is not in good contact with the hot parts of the motor, which may be improperly installed or poor contact.
The temperature sensor itself is damaged, and the characteristics of its thermal element have changed, such as abnormal thermistor resistance.
The signal processing circuit of the sensor is faulty and cannot correctly convert the temperature signal into an electrical signal that can be recognized by the tester.
Solution:
Check the mounting position of the temperature sensor probe to ensure that it is in close contact with the heat-generating parts of the motor (e.g., stator windings, motor casing, etc.). Materials such as thermally conductive silicone grease can be used to improve contact.
Use a standard thermometer to measure the motor temperature at the same time as the temperature sensor and compare the results. If the deviation is large, use a multimeter to check the resistance value of the temperature sensor and other parameters to determine whether it is damaged. For damaged sensors, replace the sensor with one of the same type.
Check the signal processing circuit of the sensor, including amplifiers, analog-to-digital converters, and other components. Use an oscilloscope and other equipment to check whether the input and output signals of the signal processing circuit is normal, if any problem, the faulty components for repair or replacement.
Fourth, the control circuit failure
1, control software failure
Failure phenomenon:
The control software of the test machine flashback, crash phenomenon, can not normally load the test program, or test parameters can not be saved and take effect after setting.
Cause analysis:
The software itself has loopholes or errors, may be in the process of updating the software file corruption, compatibility problems and so on.
Computer operating system malfunction, such as virus infection, system file corruption, etc., affecting the normal operation of the control software.
Solution:
Reinstall the control software, make sure you get the new version of the software from the official channel before installation and follow the installation instructions. If the software still has problems, contact the software vendor for technical support, which may require information such as the software's error logs to help resolve the problem.
Perform antivirus and repair system files on the computer operating system. You can use a reliable antivirus program to perform a full scan to clear out viruses and malware. For system file corruption, you can use the operating system comes with a system repair tool or reinstall the operating system to solve the problem.
2, controller hardware failure
Failure phenomenon:
The controller of the test machine can not control the motor and other equipment, all the control buttons and commands are not responsive, the controller's indicator shows abnormal.
Cause analysis:
Damage to the components on the circuit board inside the controller, such as capacitor leakage, open resistance, chip burnt.
The interface circuit of the controller is faulty, resulting in the inability to carry out normal data transmission and communication with external devices (such as motors, sensors, etc.).
Solution:
Open the controller shell (in the case of power failure and operated by professionals), use a multimeter and other tools to check the components on the circuit board, and for damaged components, replace them according to the model and specifications of the components.
Check the interface circuit of the controller, including the interface chip, connecting wires and so on. Make sure that the pins of the interface are not bent, shorted, or disconnected. Use an oscilloscope or other equipment to check whether the signal transmission of the interface is normal, and if there is any problem, repair or replace the defective components.
※ If you still can't solve the problem by the above ways and means, please contact the technical specialists of Xinhui Electromechanical Equipment Co.
