1. type and installation form of motor
1) acid pump three-phase AC asynchronous motor three-phase AC asynchronous motor is the main motive of the pump used in the chemical industry, petrochemical and other industrial equipment, it has the advantages of simple structure, reliable operation, convenient maintenance and low price. The advantages of compact size and simple starting operation. Suitable for constant torque, no speed requirements of the occasion.
2) three phase AC synchronous motor synchronous motor has special excitation system, ring or rectifier, copper and iron material consumption is increased, the price is high and maintenance is large, so it does not use much, generally used for low speed. When the power is large, it is also used in occasions such as higher power factor or higher power factor of power system.
3) DC motor DC motor has different sparks and easily worn commutators. DC power supply is needed and some disadvantages similar to synchronous motors are needed. It is usually used in cases requiring stepless speed regulation or only DC power supply.
2. main basis for selecting motor
(1) the type of motor is selected according to the requirements of the mechanical load nature and production process for the starting, braking, operation and speed regulation of the motor.
(2) according to the requirements of load torque and speed range of deterioration, starting frequently, we should consider the temperature rise limit and overload capacity of motors, deteriorate the starting speed moment, reasonably select the motor capacity and determine the cooling and ventilation mode.
(3) the environment conditions, such as temperature, are obtained according to the place of use. Humidity, dust, rainwater, gas and corrosion and inflammable and explosive gases should be considered. Considering the necessary protection methods and the structural form of the motor, the voltage level of the motor must be determined.
(4) the voltage level of the motor is determined according to the voltage standard of the enterprise power grid and the requirements of the power factor.
According to the highest speed of the sound field machinery and the performance requirements of the transition process of the electric drive speed regulation system, and the complexity of the mechanical deceleration, we select the rated speed of the motor.
In addition, selecting motors must meet the requirements of energy saving, considering operational reliability, availability, spare parts universality, installation and maintenance difficulties, product prices, construction costs, operation and maintenance costs, etc.
Selection of 3 motor types
The selection of motor type should be considered from two angles of load characteristic and energy saving. The internal speed of the positive displacement pump is a constant torque characteristic. The centrifugal pump and other vane pumps belong to the squared torque characteristic, that is, the torque increases with the increase of speed and squared relation.