1. Power circuit board fault (most common, photoelectric protection failure is typical)
This is the most common electrical fault in toilet paper rewinding machines. It manifests as photoelectric protection failure: the cutter does not stop after the photoelectric sensor is covered. After replacing the burnt-out power bridge rectifier, the new rectifier quickly burns out again. The core cause is that the burnt-out bridge rectifier short-circuits and breaks down the three-terminal voltage regulator (7805).
2. PLC system interference fault (prone to recurrence)
Symptoms include the PLC fault light illuminating, the equipment stopping irregularly, and the machine speed suddenly becoming unstable. It recovers after a power outage and restart, but recurs after a period of operation. The main cause is improper wiring (mixed high-voltage and low-voltage wiring) or electromagnetic interference from surrounding power equipment, leading to PLC calculation errors.
3. Communication bus fault (mostly caused by human error)
Symptoms include some transmission points not responding to control, the system directly reporting a communication error, and production failing to start. The most common causes, in order of frequency, are: incorrect communication parameter (station number, baud rate) settings, burnt-out or deviated resistance value of the bus end terminating resistor, and signal interference caused by mixed laying of communication and power cables.
4. DC Drive Failure: Symptoms include the motor failing to start, the DC drive reporting armature overvoltage/overcurrent/undervoltage fault codes, or irregular fluctuations in vehicle speed. Common problems: Armature overvoltage is often caused by excessive inertia from the paper roll stopping, leading to overvoltage in the generator; armature overcurrent is often caused by short circuits or aging and breakdown of components; undervoltage is often caused by loose or poor contact at the input terminals, resulting in insufficient power supply.
5. Tension Control Failure (Most Affecting Product Quality): Symptoms include the equipment operating normally, but the finished paper rolls exhibit inconsistent tension, frequent paper breaks, wrinkles, or bursting. The core causes are interference with the tension sensor signal, unreasonable tension parameter settings, and abnormal encoder speed feedback, leading to a large deviation between the actual tension and the set value.
