Temperature and humidity of stepper motor working environment

2022-01-14 11:30:07 admin 49

The operating instructions of stepper motor generally include operating temperature range of 0 ~ 50 ℃, humidity range of 20% ~ 90% RH, storage temperature range of - 20 ~ 70 ℃ and humidity range of 15 ~ 95% RH. In order to ensure the normal use of the motor, please control the temperature below 100 ℃.

Temperature requirements:

The insulation material standard of stepping motor is ULB level, that is, considering the temperature difference and safety factor inside and outside the motor, the temperature resistance of motor insulation system is within 130 °, and the motor surface temperature is required to be lower than 100 °. Considering that the general room temperature is within 40 °, the motor coil temperature rise is required to be controlled within 80K. If the motor coil temperature exceeds the limit temperature of the insulation system, it is easy to burn the insulation systems such as motor coil enameled wire, insulation slot and PCB board, resulting in motor failure (generally open circuit and short circuit).

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The rated current parameters of the motor are mainly calculated according to the heat that the motor can bear. If the working temperature of the motor is relatively high, it is necessary to reduce the working current of the motor to reduce the temperature rise, and finally control the internal heating of the motor within the range that the insulation system can bear. For example, when the ambient temperature is 60 °, the temperature rise of the motor should be controlled within 60K. Since most of the insulation materials of the stepper motor manufacturers are class B standards, it is almost impossible to correspond to a higher level of insulation materials, or the cost is too high. Therefore, when applying a higher working environment temperature, the more realistic choice is to control the temperature rise of the motor, That is, strengthen the heat dissipation conditions or reduce the working current of the motor.

The high temperature of stepping motor not only affects the safety of insulation system, but also affects the stability of permanent magnet. The permanent magnet will demagnetize with the increase of temperature, so as to reduce the working torque of the motor. The demagnetization coefficient of stepping motor magnet in the range of 130 ° can be ignored, but some manufacturers' magnets have obvious torque attenuation even within the problem range that the insulation system can withstand.

If the temperature of the stepping motor is too low, the lubricating grease of the bearing will solidify and lose the lubricating effect of the bearing. Therefore, low temperature bearings should be considered when the temperature is lower than 0 ℃. The customer can power on and heat the motor before working, and then let the motor rotate after reaching the required working temperature of the motor, but the starting process of the equipment should be set accordingly.

If low temperature resistant bearings are used, the operating temperature of the general motor will reach - 45 degrees, but the motor needs to be customized. Generally speaking, this customized product is not produced and needs to be customized by another manufacturer.

Humidity requirements:

The humidity requirement of stepping motor is mainly to avoid condensation inside the motor. The silicon steel sheet on the outer surface of the rotor and the inner surface of the stator of the stepping motor has no other rust prevention measures except that it is coated with antirust oil during processing. If the humidity is too high, it is easy to condense on the surface, resulting in rust. Due to the small gap between the rotor and stator of the stepping motor, the rust is likely to block the rotor and cause the motor to fail. On the other hand, too high humidity will also affect the insulation characteristics of insulating materials. Generally speaking, it has little effect on small stepping motors with low working voltage, but its effect on stepping motors with high driving voltage can not be ignored.

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