All kinds of motor factory in accordance with the national standard, according to the design and test data of the motor and regulation of the normal running state and conditions of each motor, called the rated operating condition of the motor. And characterization of the performance of the motor rated various values, such as voltage, current, power, etc. Is called the rating of the motor. For three-phase asynchronous motor under the specific meaning of these ratings, for your reference (in no particular order for each order, does not represent any meaning) : models. According to product performance, structure and USES the symbol rated power. The rated operating (refers to the voltage, frequency and current rating) case, the motor shaft output mechanical power to the rated power of the motor rated voltage. Motor under rated operating condition of the line ac induction motor voltage to the rated voltage of the motor. General provisions of motor voltage should not be higher or lower than 5% of the rating. Such as the three-phase stator winding can have two kinds of connection, with two corresponding rated voltage value. (if: when is higher than the rating voltage, excitation current will increase, iron losses increase, winding overheating phenomenon. When the voltage is lower than the rating, in the case of motor full load, will cause speed dropped, current is added, the winding overheating.
Low voltage, maximum torque of the motor will be significantly reduced (1) rated current. Refers to the three phase asynchronous motor under the rated voltage, rated frequency and rated load is running, the line current in the three-phase stator winding, the unit is A. Due to the connection of the stator winding in a different way, rated voltage, rated current of the motor is also different. For example, a power rating of 10 kw three-phase asynchronous motor, its winding triangle connection, the rated voltage of 220 v, rated current is 68 a. Its winding star connection, the rated voltage of 380 v, rated current for 39 a. In other words, marked on the nameplate: connection - triangle/star; Rated voltage - 220/380 v. 68/39 rated current, a. (2) the rated speed. Refers to the motor under the rated voltage, rated frequency and rated load is running, the rotor revolutions per minute, the unit for r/min. Its value is slightly lower than the synchronous speed. (3) the rated frequency. Refers to the motor by the frequency of the ac power, our country power plant produces alternating current (ac), frequency of 50 hz. Reduce the frequency, speed, stator current increase. (4) connection. Refers to under the rated voltage of the motor stator winding connection mode. There are generally two motor part star and triangle connection. The y connection, connection of windings can withstand voltage is 1/3, square root of connection mode must be stipulated in the nameplate. Otherwise, the motor will be burned.
(5) the insulation class. According to the insulation materials used in the winding, in accordance with its allowed heat degree level. Small and medium sized three-phase asynchronous motor insulation class has A, E, B, F and H class. The working temperature of the motor is mainly restricted by insulation material. If the temperature above the temperature of the insulating material is allowed to work, insulation aging quickly, it will shorten the service life. Repair of motor, the insulation of the chosen materials should comply with the regulations of nameplate insulation class. (6) work quota. Refers to the works of the motor, namely in the duration of the provisions under the working conditions of running or working cycle. Motor operation, according to the heating condition can be divided into three basic operation modes: continuous operation, short run and intermittent operation; Run continuously - the power of the running for a long time, as stipulated in the nameplate, such as the use of the water pump, fan and machine tool equipment on the motor way is continuous operation mode. The short run - time is only allowed within the stipulated time according to the rated power operation, and again before starting should conform to the provisions of the enough cooling time downtime. Intermittent operation - motor running in intermittent way, such as cranes and crane equipment with motor is intermittent operation mode respectively. The point at which the motor run for a long time continuously, the value of working temperature higher than the ambient temperature. Rules surrounding environment in our country the highest temperature of 40 ℃. If, for example, the permission of the motor temperature rise to 65 ℃, it allowed working temperature is 650 = 40 to 105 ℃. Without the permission of the motor temperature rise associated with grade insulating materials used. In operation of the motor temperature rise a great influence on the service life of insulation materials, theoretical analysis shows that in the operation of the motor insulation temperature higher than the rated temperature 8 ℃, its service life will be shorten half.
(7) the rated power factor. Refers to under the rated output power of the motor, stator winding between phase voltage and phase current phase Angle cosine, about 0.70 ~ 0.90. Motor no-load running, the power factor of about 0.2 left again. The higher the power factor of motor, power distribution equipment utilization ratio, the higher the starting current. Refers to the current motor at starting moment, it is commonly used and the ratio of the rated current of multiples. The three-phase asynchronous motor starting current is usually 4 to 7 times the rated current. The rotor voltage. Wound rotor asynchronous motor stator winding with rated voltage, the voltage between the rotor rotates not two slip ring. Rated efficiency. (8) for motor, the input power and output power range, the difference is equal to the motor itself loss power, including copper loss, iron loss, mechanical loss and so on. Efficiency refers to the ratio of output power and input power, which is about (75 ~ 92) %. The higher the efficiency, the smaller the loss of the motor rotor current. Wound rotor asynchronous motor used in the rotor current rating. Starting torque. Starting torque is the point at which the motor starting torque, it is commonly used and the ratio of the rated torque multiples. Usually 1-1.8 times www.facebook.com/dongfeng.motor the rated torque. The weight. Refers to the weight of the motor itself, when lifting handling in order to offer reference.
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