General
   YB2 ranges of three-phase induction motors are flame-proof motors obtained by renewal and generation-changing of YB ranges of motors. The
performances of the products have come up to advanced international standards.
   The motors have the advantages of higher efficiency, energy saving, higher locked-rotor torque, lower noise, smaller vibration, safe and reliable operation and beautiful appearance, etc. The outputs, mounting dimensions and their corresponding relationships comply with IEC standards.

Construction
    YB2 range of motors comply with GB3836.2, Electrical Apparatus for Use in Explosive Atmosphere part2:Flame-proof Enclosure `d' . The flame-proof constructions and their parameters have refered to IEC60079-1,Construction and Verification Test of Flame –proof Enclosure for Electrical Apparatus, and EN50018, Electrical Apparatus for Use in Explosive Atmosphere: Flame-proof Enclosure "d". The motors are made into flame-proof type, and are suitable for use in explosive gas atmosphere, which can be divided into two grorps. Group I is used for coal mine and marked with ExdI; Group II is used for explosive gas atmospheres other than coal mine and marked with ExdIIAT4 ExdIIBT4 ExdIICT4 .
    Degree of protection by enclosure of motors is IP55.
    The frames of motors are designed with parallel cooling ribs which are distributed vertically and horizontally.
    The bearings of motors are ball bearings. The fans are of small diameter and wide vanes. In addition to them, reasonable electromagnetic parameters and proper slot combinations and slot-skewing slopes are selected so that the vibration and the noise of motors have effectively been controlled.
    The stator windings of the motor are class F insulated.When the altitude above sea level and ambient temperature are in accordance with the values specified by the standard,the temperature rise limit of stator windings is 80K(resistance method). For frame size 315L2-and 4-pole motors and frame size 355 motors, the temperature rise limit is 105K.
    The cable entry form for the terminal box of YB2 range of motors is of cabtyre cable. The terminal box is provided with three terminals (for single voltage) or six terminals(for double voltages). The terminal box is located on the top of the motor. On request of user, armoured cable can also be applied.
    The direction of rotation of the motor. For frame sizes H63 to 280 and H315 to 355 motors (4 to 10-poles), the direction of rotation may be clockwise and anticlockwise, and for frame sizes 315 to 355 2-pole motors, the direction of rotation is clockwise as viewed from the shaft extension. If the motor is required to rotate anticlockwise, please specify it when ordering.

Ambient Conditions
    Ambient air temperature changes with season, but does not exceed 35°C (underground coal mine) or 40°C (the factory ), and is not lower than -15°C.
    Altitude above sea level: up to 1000m.
    Note: when ambient air temperature and altitude are different from the above, refer to GB755.
    In the moistest month, the monthly-average maximums relative humidity is 90%, and the minimum temperature does not exceed 25°C in this month (in the factory). In the underground coal mine, the highest relative humidity does not
exceed 95%.
    In the underground coal mine (non-excavating working) or the factory have easy-ignition and explosive gas , steam
and air mixtures , which temperature class T1~T4.
    Rated frequency: 50Hz.
    Rated voltage: 380V, 660V and 380/660V.
    Note: If you have special requirements for frequency,voltage, ambient air temperature and altitude, etc. pleacify them when ordering.

Ordering Information
1. When placing an order,please specify motor’s type, output, number of poles, voltage, frequency,mounting, arrangements and other requirements.
2. Special orders of motors with following design variations can be accepted upon agreement:
    a. Double shaft extension.
    b. With terminal box on the left-hand side when looking at the driving end.
    c. Thermistor protection.