When we use the electric motor, we will always encounter some small problems, today let's learn about the motor of 13 small knowledge about the working principle
电动机为什么会产生轴电流？
The current in the shaft - bearing housing - base circuit of the electric motor is called shaft current.
- 轴电流产生的原因。
- 磁场的不对称性。
- 电源电流中的谐波。
- 制造和安装不良，转子偏心造成气隙不均匀。
- 可拆卸定子铁心两个半圆之间的间隙。
- 还有一种扇形叠片式定子铁心的片数搭配选择不当。
危害：电动机轴承表面或滚珠被侵蚀，形成过程点微孔，使轴承运转性能恶化，摩擦损失和热量增加，最终导致电动机轴承烧毁。
Why can't the general electric motors be used in highland areas?
Altitude has a negative impact on electric motor temperature rise, electric motor corona (high voltage motors) and DC motor commutation, electric generator .
The following three aspects should be noted:
- The higher the altitude, the greater the temperature rise of the electric motor and the smaller the output power. But when the temperature decreases with the rise in altitude enough to compensate for the effect of altitude on temperature rise, the rated output power of the electric motor can be unchanged.
- Anti-corona measures should be taken when high voltage motors are used in the plateau.
- Altitude is not good for DC motor commutation, pay attention to the choice of carbon brush material.
电动机为什么不宜轻载运行？
Electric Motor operation at light load results in;
- 电机功率因数低，电能
- 电机效率低，机械能
- 造成设备浪费和运行不经济。
电动机过热的原因有哪些？
- 负载过大。
- 电动机缺相。
- 风道堵塞。
- 低速运转时间过长，转子转速过高。
- 电源谐波过多，转换电能。
电动机长期投入使用前需要做什么？
- 测量定子和电机绕组各相之间以及电机绕组对地的绝缘电阻。
绝缘电阻R应满足下式。
R＞Un/(1000+P/1000)(MΩ)
Un：电动机绕组额定电压（V）
P：电机功率（KW）
对于Un=380V的电机，R＞0.38MΩ。
如果绝缘电阻低，则可以。
a：电机空载运行2～3h干燥。
b：用额定电压10%的低压交流电通入绕组或三相绕组串联直流烘烤，保持电流为额定电流的50%。
c：利用风扇送入热风或加热元件进行加热。
- 用电风扇清洁电动机。
- 更换轴承润滑脂。
Why can't I arbitrarily start the electric motor in a cold environment?
电机在寒冷环境中放置时间过长就会出现这种情况。
- 电机绝缘开裂。
- 轴承润滑脂冻结。
- 导体接头的焊料粉化。
因此，在寒冷环境下应对电机进行加热和保存，运行前应对绕组和轴承进行检查。
造成电动机三相电流不平衡的原因有哪些？
- 交流电机三相电压不平衡，检查电压等级。
- 电动机内部相支路焊接不良或接触不良。
- 电动机绕组匝间短路或电动机对地或相间短路。
- 电机接线错误。
为什么60Hz的电动机不能接50Hz的电源？
The electric motor is generally designed to make the silicon steel sheet work in the magnetization curve of the satiation area.
When the supply voltage is certain, reduce the frequency will increase the flux, excitation current, resulting in increased motor current, copper consumption, and eventually lead to higher motor temperature for the ac motor, and in serious cases, may also burn the electric motor due to coil overheating.
电动机缺相的原因有哪些？
Power supply:
- Poor switch contact.
- Transformer or line disconnection.
- Fused insurance.
Electrical Motor side:
- Loose motor junction box screws poor contact.
- Poor welding of internal wiring for electric circuit .
- electric Motor winding disconnection.
电机异常振动和异响的原因有哪些？
机械方面。
- Poor bearing lubrication and bearing wear.
- Loose fastening screws.
- There are debris in the electrial motor.
电磁方面。
- induction Motor overload operation.
- Three-phase current imbalance.
- Lack of phase of ac motor .
- Stator, rotor winding short-circuit fault for the induction motors .
- Broken bars caused by open welding of the cage rotor part.
启动电动机之前需要做什么？
- Measure insulation resistance (should not be less than 0.5MΩ for low voltage ac motor).
- Measure the power supply voltage. Checking whether the motor wiring is correct and whether the power supply voltage meets the requirements.
- Checking whether the starting equipment is good.
- Check whether the fuse is suitable.
- Check whether the electric motor grounding, zeroing is good.
- Checking whether the transmission device is defective.
- Check whether the electrical motor environment is suitable, remove flammable materials and other debris.
电动机轴承过热的原因有哪些？
induction Motor itself.
- 轴承内、外圈配合过紧。
- 零件形状公差问题，如阀座、端盖、轴等零件同轴度不好。
- 轴承选择不当。
- 轴承润滑不良或轴承清洁不良，润滑脂中有杂物。
- 感应电机的轴电流。
使用电机方面；
- 机组安装不当，如电动机轴与被拖动装置轴的轴同轴度有要求。
- 皮带轮拉得太紧。
- 轴承维护不良、润滑脂不足或超过使用期限、干燥变质。
电机绝缘电阻低的原因有哪些？
- 电机绕组受潮或进水。
- 电机绕组上积聚灰尘或油污。
- 绝缘老化。
- 电机引线或端子板绝缘损坏。
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