Application of centrifugal dewatering machine
Application of ACI Inverter in Centrifuge and Industrial Dewatering Machine
Industrial centrifuge is one of the main equipment of India chemical industry, it is mainly through the action of centrifugal force to solid-liquid separation, by feeding, washing, dehydration, including knives, unloading and other parts, including feeding, washing, including knives, such as the unloading part is through the solenoid valve, pneumatic control valve, centrifugal kettle is the main components of solid-liquid separation is realized, by a three-phase AC motor through a belt drive. According to the process characteristics in the beginning of material is mainly a mixture just started when the load is relatively large, when out of the outer kettle reaches a certain speed centrifugal liquid under the action of centrifugal force, the liquid part is first isolated, with the further increase of motor speed, load decrease. According to the process requirements, generally divided into several different speed to achieve the separation effect.
二. Application of frequency converter in centrifuge
1. Application of frequency inverter
As a kind of industrial control equipment, inverter has been continuously updated and developed in recent years. It has been widely used in all walks of life. With the development of power electronic technology, frequency control theory, microcomputer control technology continues to mature, the performance of the inverter, and constantly improve the function has also been enhanced: such as multi speed, programmable automatic operation and communication function, which makes the transducer can adapt to a variety of applications. According to the production process of the centrifuge, multi speed function can be used to control the inverter in inverter centrifuge, generally with built-in brake unit or external brake unit, which can solve the centrifuge in parking because of inertia caused by parking difficult problem.
2.G11 ACI series inverter in the application of the centrifuge
Centrifugal load is a constant torque and large inertia load, which is used in the production of Guangzhou Mount Everest Electric Co., Ltd. G11 ACI series of general purpose inverter. The motor power is 11kW, 6 pole, for example, the use of G11-0015T4 ACI inverter, the external control circuit is shown in figure 1. The starting signal K1 connected inverter FWD multi function control terminal, K2 multi speed 1 X1 K3 converter, multi speed 2 X2 converter, K4 converter fault reset X3, according to the selection of three speed low speed and medium speed operation needs and high-speed operation, the specific operation speed by setting parameters the corresponding.
图1 Schematic diagram of the external control of the centrifuge
3、ACI inverter main parameters setting
The main circuit of the general inverter is shown below.
According to the load characteristics of the centrifuge, set the following main parameters:
Speed deceleration time
Reversal of prohibition
Low speed acceleration time
Slow deceleration time
High speed acceleration time
High speed deceleration time
Deceleration + DC brake
Multi velocity 1
DC braking time
Multi velocity 2
DC braking current
Speed acceleration time
4、Application of ACI brake unit
Centrifuge is a large inertia load, the inverter control required increase braking unit to meet the requirements, but ACI 15KW and 15KW inverter under built-in brake unit, not only for the user to save the installation space, but also saves cost. The operating characteristics of the motor when the motor speed is higher than that of know the actual speed when the motor is running in the synchronous generator, the output frequency of inverter shutdown began when the centrifuge started to decline due to the inertia of the load deceleration time, speed centrifuge at little change, causing the actual motor speed is higher than the synchronous speed, motor power in the braking state, known by the main circuit of inverter at this time, the motor side of the feedback of energy through diode D1-D6 feedback to filter capacitor C1, DC circuit of C2 inverter circuit, when the bus voltage of the Ud converter will rise, DC bus voltage is too high will make the frequency converter to avoid overvoltage protection, even damaging the inverter, therefore, must be installed when the brake assembly. The brake unit control circuit detects the DC bus voltage reaches a certain value to control the switch tube IGBT The braking resistor RB is connected to the circuit and the feedback of the motor is dissipated on the resistance to maintain the normal bus voltage Ud.
三、Debugging attention problem
According to the load characteristics of the centrifuge, should pay attention to:
(1) centrifuge load torque requirements higher, may start a difficult situation, it may be appropriate to enhance the torque compensation of inverter, ACI G11 series of d0.09 parameters is 5%, but the starting torque compensation can not be too large, otherwise it may appear over-current (fault code OC), overload (fault code OL) the alarm, if in the accelerated overcurrent alarm should be appropriate to extend the time of acceleration;
(2) centrifuge with large inertia, if the inverter must be installed according to the deceleration time of parking brake unit, the choice of converter brake resistors that are manual, according to the operation manual, normal operation due to the consumption of energy and braking resistance heating, can be properly enlarged resistance power and braking time.
(3) general centrifuges installed at the operation site, multiple inverters concentrated on the control room, and if the distance exceeds the allowable range of the frequency converter centrifuge should adopt corresponding measures, such as reasonable distribution of main return route and control line, with output reactor or filter to prevent the output current of inverter output line is longer, because of the distributed capacitance increases increases, or consider increasing the capacity of the inverter.
Centrifuge uses VVVF can speed according to different process requirements, selection of multi speed operation can be conveniently according to different materials, at the same time using variable frequency control soft start of the motor, reduce the impact on the grid, the inverter has the protection function of flow, overload, overvoltage and other rich, when the load or the motor is abnormal for frequency inverter downtime and quickly blocked output, which can timely protection of motor.