Elevator failure confirmation skills - Solutions - Huaqiang Electronic Network

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Mastering elevator repairs requires a deep understanding of the system, as well as the ability to identify and resolve issues efficiently. The process involves analyzing failure symptoms, determining the root cause, and locating the exact problem. This not only demands experience but also some practical troubleshooting techniques. In this article, I will share three useful tips for identifying faults in elevators.
1. Confirming Faults in Rotary Encoders: Example 1: A GPS-‖ elevator experienced inaccurate leveling with a “Teng Yiteng” (sliding) phenomenon during operation. After extensive checking, it was found that dust had blocked several photoelectric holes on the rotary encoder, causing the issue. Cleaning the encoder resolved the problem. Example 2: An P90-50 elevator would crawl about 50mm after starting and then stop. Despite no obvious signs of malfunction, the issue was traced back to a loose connection between the rotary encoder and the microcomputer. Example 3: A VVVF elevator would suddenly stop during operation, then level itself and resume normally. The problem wasn’t due to the brake or safety circuits, but rather sudden wear on the rotary encoder, which caused signal interruption. Example 4: A GPS-CR elevator had severe shaking when running at high speed, especially when stopping at multiple floors. After checking the main circuit and drive unit, it was discovered that a copper grounding piece at the motor’s tail had deformed, causing misalignment. Replacing the part fixed the issue. Faults related to rotary encoders are common and can be tricky to diagnose. One effective method is to temporarily disconnect the encoder feedback and switch to open-loop control. If the motor still runs smoothly, the issue is likely with the encoder. Otherwise, the problem lies elsewhere. However, always ensure the elevator is not operated near the top or bottom stations during this test for safety reasons.
2. Quick Diagnosis of Door Lock Faults: Door lock faults are one of the most frequent issues in elevators. When the elevator cannot operate due to a door interlock problem, you can check the machine room control panel for fault codes. For high-rise buildings, where manually checking each floor is impractical, a segmentation method can help. By shortening specific lines and using a multimeter, you can isolate the faulty floor quickly. This approach significantly reduces time and effort in troubleshooting.
3. Identifying Doorknife and Door Roller Contact Issues: A sudden elevator stop could be due to the door lock circuit momentarily opening, the speed limiter tension device touching the rope, or the doorknife coming into contact with the door roller. For PLC-controlled elevators, inserting a specific program segment allows monitoring of the counter value. If the count increases, it indicates a possible doorknife-to-roller contact. Careful observation and analysis can reveal such issues effectively. In conclusion, elevator repair requires both technical knowledge and practical skills. By staying observant, learning from each case, and continuously improving your methods, you can become more efficient and confident in handling complex problems.