Could everyone help analyze the reasons for the actuator’s thermal protection?
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It’s a gas ball valve with a DN600 bore and extended stem, exported to North America. The actuator used is the Z90 model, which features a two-stage reduction gearbox, operates at 480V, and is an intelligent integrated unit. During commissioning, a problem was identified: the motor in the actuator heats up extremely quickly during operation, causing the valve to trigger its thermal protection mechanism at just 50% operation. Can everyone figure out what the reason is?
The reasons for thermal protection due to overheating of the actuator may include the following: 1. **Motor overload**: This can occur when the load on the valve exceeds the motor’s capacity, or when there is a mismatch between the motor and the reducer, resulting in excessive load on the motor. 2. **Voltage issue**: If the input voltage is higher or lower than the voltage specified for the motor, it may result in poor operating efficiency and excessive heating of the motor. 3. **Poor insulation**: If there are issues with the motor’s insulation, it can lead to short circuits between the motor’s components, resulting in overheating. 4. **Poor lubrication**: Insufficient lubrication of the reducer or motor bearings increases friction, leading to heating. 5. **Frequent operation**: If the actuator is operated frequently over a short period of time, it may generate excessive heat, leading to thermal protection. 6. **Poor heat dissipation**: The heat dissipation system of the actuator is poorly designed or the heat dissipation channels are blocked, preventing effective heat dissipation. It is recommended to conduct checks and adjustments from these aspects to see if the overheating problem can be resolved. .
Possible causes: Excessive motor load: During the valve opening process, especially when it is nearly fully open or in a partially open position, the motor load may increase significantly due to increased fluid resistance or changes in pressure within the pipeline. If the actuator is not properly selected or has insufficient design power, overheating may occur when the load increases. Poor heat dissipation: There may be issues with the cooling system inside the actuator, such as an improper design of the heat sinks, a faulty cooling fan, or blocked cooling channels. External environmental conditions can also affect heat dissipation, such as high temperatures or poor air circulation. Electrical issues: Unstable voltage or excessively high supply voltage may cause the motor to overheat. The motor windings may have short circuits or open circuits, resulting in abnormally high current levels. Control logic issues: If the control logic is not set properly, such as with too fast start-up speeds or excessive acceleration, it can also cause the motor to generate a large amount of heat in a short period of time.
There is no overload, the voltage is normal at 480V; as for the other reasons, they are not major issues.