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What should I do after the AC MOTOR gets wet?
Jul 24, 2018

In the actual production of many enterprises, it is often found that some AC MOTORs are not used for a period of time. When they are re-enabled, the insulation resistance of the AC MOTOR windings is reduced. Especially in the rainy season, the air humidity is high, and the insulation value is even reduced to zero. When it is dry, the insulation resistance and absorption ratio should reach the specified value. If it is put into operation, it may cause insulation breakdown of the AC MOTOR coil and cause an accident.

1. External heat source heating method

After the dehumidified AC MOTOR is first disassembled, it is baked in a AC MOTOR with a high-power incandescent bulb, or the AC MOTOR is placed in a drying room for drying. This method is easy to operate, safe and reliable, but only for small AC MOTORs that are easy to remove. For large and medium-sized AC MOTORs that are difficult to dismantle, the workload is relatively large, and the feasibility is also reduced. It should be noted that when the method is operated, the bulb or the heat source should not be too close to the coil to prevent the coil from being burnt, and the AC MOTOR casing may be covered with a canvas or the like for heat preservation.

2, electric welding machine drying method

2.1. AC welding machine drying method Before the operation, the six terminals of the wet AC MOTOR winding are connected in series, and the casing is grounded, so that the three sets of windings can be heated and dried. In order to monitor the current change during the drying process, it can be serialized. Only the ammeter, observe whether the current reaches 60% to 70% of the rated current of the AC MOTOR. Drying the AC MOTOR with AC welding machine does not need to dismantle the AC MOTOR, which reduces the workload. At the same time, the AC MOTOR uses its own resistance to heat when the power is applied, so that the coil is evenly heated, and the drying effect is better, but this method is only suitable for 100kW or less. The AC MOTOR can not be used for a long time, because the current applied to the transformer of the welding machine when the AC welding machine is working is large, and it cannot be used for a long time, otherwise the welding machine may be burned out.

2.2, DC welding machine drying method Operation wiring and AC similar, the string current meter should be DC current meter. Drying the damp AC MOTOR with a DC welding machine is easy to operate, and it can dry the large and medium-sized AC MOTORs and high-voltage AC MOTORs for a long time. Because the current multi-purpose DC inverter welding machine, it uses three-phase AC 380V voltage after three-phase bridge rectification, filtering and then supplying inverter with new IGBT as power switching device for frequency conversion processing, and then stepping down by the intermediate frequency transformer. After the rectified output is available for the power supply required for soldering, the logic control circuit formed by the integrated circuit processes the feedback of the voltage and current signals to realize the closed-loop control of the whole machine, and adopts pulse width modulation PWM as the core control technology, thereby obtaining fast Pulse width modulated constant current characteristics, and a dedicated cooling fan for cooling. In this way, when the welding machine is operated for a long time or when the current is high, the internal components are not damaged due to long-time high-current operation, so the large and medium-sized AC MOTORs can be used for a long time. It is worth noting that: when drying by these two methods, all the joints must be in good contact and fastened. The electric wire of the welding machine should use special wires, and the cross-sectional size should meet the current carrying capacity of the welding machine output current. Pay attention to the cooling of the welding machine's own transformer, and ensure that the insulation resistance of the AC MOTOR can not be lower than 0.1MΩ. Also pay close attention to the AC MOTOR winding temperature and adjust the voltage and current in time.

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