Note*: The neutral pole (N pole) of the four-level product is divided into four types of
A-type N-pole, no overcurrent tripping element is installed, and the N-pole is always on, not combined with other three-level;
B-type N-pole No overcurrent trip element is installed, and the N pole is combined with other three levels (N pole is closed first and then opened);
C-type N pole is installed with overcurrent trip element, and the N pole is combined with other three levels (N The pole is closed first and then opened);
D-type N pole is installed with an overcurrent trip element, and the N pole is always on, and does not open and close together with other three levels;

1. The upper limit of ambient air temperature is +40℃, the lower limit is -5℃, and the average value of 24h does not exceed +35℃.
2. Altitude: The altitude of the installation site does not exceed 2000m.
3. Relative humidity: the relative humidity of the atmosphere does not exceed 50% when the ambient air temperature is +40℃, and it can have a higher relative humidity at a lower temperature; the monthly average maximum relative humidity of the wettest month is 90%, and the The monthly average minimum temperature of the month is +25°C, taking into account the condensation on the surface of the product due to temperature changes.
4. Pollution degree: Pollution degree is 3