Indicator Fault
1. Fault Symptom:
After powering on the electric actuator, the power indicator light was off, there was no feedback from the servo board, and the actuator did not respond when a signal was given.
Fault Diagnosis and Repair Process:
Since the power indicator light was off, first check for an open circuit in the fuse. After checking that the fuse was intact and considering the fault symptoms, it was concluded that the fault likely occurred in the power supply section of the servo board. Next, check the power indicator light. Using a multimeter, the indicator light was found to be open. Replace the indicator light and the fault was resolved.
Conclusion: An open circuit in the power indicator light can cause the entire servo board to malfunction.
2. Fault Symptom: (Discovered during commissioning)
After powering on the actuator, the electric actuator's actuator operated normally when a signal was given, but did not respond when a signal was given.
Fault Diagnosis and Repair Process: First, carefully check the feedback circuit to confirm that the feedback signal was faulty. If the open indicator lighted when an open signal was given, the actuator was operating normally. If the close indicator lighted when a close signal was given, the actuator did not respond, indicating a problem with the thyristor in the close circuit. First, check the close indicator light. Using a multimeter, the close indicator light was found to be open. Replace the indicator light and the fault was resolved.
Conclusion: The thyristor does not operate when the Close and Open indicators are off (open circuit).
Resistors and Capacitors
1. Fault Symptom:
After the electric actuator is powered on and a signal (e.g., 75%) is applied, the actuator fully opens and then returns to the designated position (75%).
Fault Diagnosis and Repair Process:
Based on the above fault symptoms, the first step is to determine whether the problem lies with the servo release board or the actuator. Remove the servo release board from the actuator and connect the power cord directly to terminals X5/1 and X5/4. The actuator will operate in the Close direction. Connect the power cord to terminals X5/1 and X5/2 and the actuator will operate in the Open direction. If the actuator does not operate normally, the fault is in the actuator. Using a multimeter to test the motor windings, the resistance on both sides of the capacitor is normal. Measuring the resistance on both sides of the capacitor reveals an open circuit. Replacement of the capacitor eliminates the fault.
Conclusion: When encountering the above fault symptoms, the first step is to determine which component is causing the problem and ultimately determine the root cause.
2. Fault Symptom:
After powering up the actuator and applying a closing signal (4mA), the actuator fully opened and then fully closed.
Fault Diagnosis and Repair Process:
First, remove the servo release board and directly power up the actuator. The original fault persists. The resistor was checked and found to be normal, indicating the resistor is fine. The motor windings were checked and found to be normal, indicating the motor is fine. Based on this, the fault is likely a faulty capacitor. The capacitor was replaced, and the fault was resolved.
Conclusion: When this problem occurs, the resistor and capacitor are the primary suspects.
Others
1. Fault Symptom:
Onsite, as soon as AC220V power is applied, the protective switch immediately trips, indicating that the actuator's servo release fuse has blown.
Fault Diagnosis and Repair Process:
First, use a multimeter to test the actuator's motor windings. The resistance is near zero, indicating a short circuit. Then, test the resistance across the brake. The resistance is near infinity, indicating a faulty brake. A normal value should be around 1.45K. The final solution was to replace the brake and motor, reinstall the servo release board fuse, and re-commission to restore normal operation.
Conclusion: This situation likely occurred because the brake failed, locking the motor and not being discovered promptly on-site. This caused the motor to remain locked for an extended period, overheating, and ultimately damaging the insulation between the motor phases.
2. Fault Symptom:
The actuator's direction of movement was not controlled by the input signal.
Diagnosis and Repair Process:
First, we checked the two current-limiting resistors and phase-shifting capacitors, finding no abnormalities. We then used a multimeter to check the motor's winding resistance, revealing a resistance of 1.45 MΩ (which varied periodically), indicating a faulty motor winding. The final solution was to replace the motor.
3. Fault Symptom:
The actuator's direction of movement was not controlled by the servo release board.
Diagnosis and Repair Process:
First, we had the user use a multimeter to test the two current-limiting resistors, phase-shifting capacitor, and motor winding resistance. The user's results were consistent with the final data we provided. The three factors that affect the actuator's direction of rotation are: 1. The motor's windings; 2. The current-limiting resistor; and 3. The phase-shifting capacitor. There are no other possible factors.
4. Fault Symptom:
The motor did not move regardless of any signal applied on-site.
Fault Diagnosis and Repair Procedure:
Applying power directly to the motor windings did not cause any rotation. Even with the brake removed, the motor still did not rotate when powered on. Testing the motor winding resistance showed normal results, and the actuator operated normally when powered on. The test results were all normal, except that the motor did not rotate when powered on. The motor rotor was suspected. Disassembling the motor revealed that the rotor could not be turned manually. A solid layer of dust had formed between the rotor and the motor end cap. After cleaning the dust and adding a little lubricant, it could be turned manually. The motor was reinstalled and fitted with the actuator. Power was applied and the actuator operated normally. The actuator was re-adjusted.