[Guide] The basic operating conditions of the motor specified in GB755 include the requirements for altitude, ambient temperature, cooling medium and relative humidity, electrical conditions, changes in voltage and frequency during operation, and midpoint grounding of the motor.

1. Deviation requirements of motor operating voltage and frequency

●Voltage deviation. When the power supply voltage of the motor (if AC power supply, the frequency is rated) changes between 5% above and below the rated value, the output power can still maintain the rated value. When the above voltage changes, the performance and temperature rise of the motor are allowed to deviate from the regulations.

●Frequency deviation. When the deviation of the rated value of the frequency (voltage is rated) of the AC motor does not exceed ±1%, the output power can still maintain the rated value.

●Voltage and frequency deviation at the same time. When the voltage and frequency of the motor deviate at the same time (the deviations of the two do not exceed ±5% and ±1% respectively), if both are positive, and the sum does not exceed 6%; or both are negative, or When the positive and negative values respectively, and the sum of their absolute values does not exceed 5%, the motor output power can still maintain the rated value.

●Symmetry of voltage and current. For AC motors, the sinusoidal distortion rate of the power supply voltage waveform does not exceed 5%; for multi-phase motors, the negative sequence component of the power supply voltage of the motor for long-term operation does not exceed 5%, and the power supply voltage of the short-run motor does not exceed a few minutes The negative sequence component does not exceed 1.5%, and the zero sequence component of the voltage does not exceed 1% of the positive sequence component.

2. Operating environment requirements of the motor

●Altitude. When the motor is designed, it should be able to operate normally when the altitude does not exceed 1000 meters. Special requirements should be stated when ordering, and necessary measures should be taken in product winding, insulation, etc.

●Ambient temperature. The standard specifies the maximum and minimum ambient temperature of the motor. The ambient temperature of the motor operation varies with the season. The maximum ambient temperature generally does not exceed 40 ℃, but some special motors can exceed 40 ℃, and some motors have higher ambient temperatures. The minimum ambient temperature for motor operation is -15℃; the minimum air temperature for micro motors is -55℃. The minimum ambient air temperature for motors using water as the primary or secondary cooling medium is 5°C.

●Ambient air relative humidity. The standard stipulates that the monthly average maximum relative humidity of the wettest month of the motor operating location is 90%, and at the same time, the average monthly minimum temperature of the month is not higher than 25 ℃.

3. The neutral point of the star-connected motor is grounded

When the AC motor is star-connected, it should be able to run continuously with the neutral point at or near ground potential. If the insulation of the wire end of the motor winding and the neutral point are different, it should be stated in the instruction manual of the motor. Without the consent of the manufacturer, it is not allowed to ground the neutral point of the motor or connect the neutral points of multiple motors to each other. .