Delta converter in the horizontal spiral centrifuge application

pick to: This article introduces the structure of the horizontal spiral centrifuge, as well as the Delta Series B inverter in the use of horizontal spiral on the centrifuge.
Key words: horizontal spiral centrifuge shared DC bus converter
1 The introduction of
  horizontal spiral centrifuge (the horizontal screw centrifuge) in Figure 1 is widely used in petroleum, chemical, metallurgy, medicine, food, light industry sectors. Can be used for dehydration and classification of solid, liquid can also be used to clarify, in an important position in the field of centrifuges. As a result of this stand-alone centrifuges have the capacity to deal with large, easy to use and can operate automatically in a row, low labor intensity, as well as a small footprint and low maintenance costs, it has been since the 1950s, the sludge dewatering centrifuge spiral in Widely used, gradually replaced by other mechanical dehydration become a large-scale municipal wastewater treatment plant sludge dewatering equipment of choice. Suspension through the spiral in the center of the conveyor feeding tube into the high-speed rotating drum, as a result of centrifugal force, heavier or larger particles thrown by rotating the drum wall, through the little-helix of injection hole to smoke Drums, and less solid particles and liquid bulk of the drum through the overflow hole overflow drum. Suspension from a stepless speed regulation can be the screw feed.

Figure 1 Horizontal Spiral centrifuge

Figure 2 horizontal spiral centrifuge profile
  Decanter centrifuge with two-motor drive (shown in Figure 2), and pieces of the initiative linked to electric motors work in a state of the main motor, and follower of motor connected to drum due to the differential remains the role of the generators The state deputy motor, which needs the speed with precision. The transmission mode in the early 60s had been used for the laboratory, but the drive way for decades in the industry was not widely used, The reason: the key is vice renewable electrical energy in the first place the technical conditions can not be reasonable to use. Therefore, in most cases, Decanter centrifuge vice motor are removed and the installation of the eddy current brakes.
  power with the rapid development of electronic technology, in recent years greatly increase the cost of the converter, even the bus were also becoming more mature, domestic manufacturers have a lot of centrifuges are exploring the electrical double-double of the inverter-driven program. In the scheme, Lord, the vice-electric converter with a common drive, with DC bus in an appropriate manner and then, a better solution to the continuing vice-electric power generation. Its application in increasingly short of energy, of particular importance.
the development trend, the horizontal screw drive from the eddy current brake serious energy development To the most mainstream dual-frequency dual-motor drive.

3 control program
schematic in Figure 3

Figure 3 control system schematic
Wiring diagram in Figure 4:

Figure 4 Control System wiring diagram

in Figure 4, the air is a switch for each of the inverter into the line protection device, which should be Contact with the air-assisted switch, which Mainly due to the contactors to be connected to the switch at the same time meet the air support and close contact transducer normal operation of these two conditions, or disconnect the contactor.

because of the complexity of the actual on-site work environment often lead to fluctuations in the power grid and generate high harmonics, the use of line into the reactor will be able to effectively prevent these factors impact on the frequency converter can also be used to increase the power supply impedance and to help absorb the vicinity of Equipment to work when the main power surge voltage and the peak voltage, and eventually the protection of the rectifier unit converter.

system configuration: 300B43A inverter control of the main motor 30kW, 075B43A inverter motor control, Deputy 7.5kW. Inverter action by the panel buttons to control the frequency of adjustment from the control panel potentiometer. There are panel tachometer indicating the actual motor speed, signal converter from analog signals to provide output.

4 a total of DC bus approach

  for the common frequency converter, the use of shared DC bus is a very important point in the electricity must fully take into account the frequency converter control, transmission failure, and enter the main characteristics of the load circuit protection. The chart below shows, in which a relatively wide range of applications. The program includes 3-phase into the line (to maintain the same phase), DC bus, General inverter group, public or braking unit of energy feedback device and a number of ancillary components.

Figure 5 DC converter share bus diagram

the program has the following characteristics:

(1) the use of a complete converter, rather than simply use the traditional sense of the rectifier bridge plus a number of programs inverter;
(2) do not need to have a separation of the bridge rectifier, charging unit, capacitor and inverter;
(3) each converter can be separate from the DC bus and not separated Impact on other systems;
(4) through the chain of contactors to control the DC converter to share the bus contact;
(5) soon hung on to protect molten DC bus converter on the capacitance of the unit;
(6) all linked in the bus on the inverter must be used with a three-phase power.
  inverter in order to ensure a smooth power-on to put up after the DC bus, or converter after the failure to quickly disconnect and DC bus converter to further reduce the scope of the failure to use the occasion of the converter signal must be 24VDC Or dry contact output signal, the output signal, including at least:
(1) ready signal: the output signal converter that is effective error-free, normal bus voltage, you can start to receive orders;
(2) failure signal: that the signal output Inverter failure.
  FU for the semiconductor quick fuse, rated voltage is usually optional 700VDC, rated current must be taken into account in the electric drive motor or when the maximum braking power, under normal circumstances, can be 125% of rated load current can be.
  MC for the DC contactors, rated voltage optional 650VDC, its current rating should be based on the same drive motor when the brake to set the maximum current, under normal circumstances, the election can be 120% of rated load current.

5 parameters set
the highest operating frequency Set 01-00 = 50
maximum voltage frequency set 01-01 = 50
the maximum output voltage set 01-02 = 380
the first time to speed up the set 01-09 = 180
time to slow down in the first set 01-10 = 180
frequency of the first sources of instruction set 02-00 = 1
the first operation of the command to set the source of 02-01 = 1
multi-output 03-00 = 20
analog output signal selection 03-05 = 4
five multi-function input command 04-08 = 30

6 test data

stopping into line voltage: 3PH 380VAC
bus voltage: 535VDC
main motor running Frequency: 49.1Hz
vice-frequency motor running: 38.4Hz
main electric current: 25A
Vice electric current: 7A
DC bus voltage: 495V
speed brake units transducer in the open without a stable, normal bus voltage.

7 conclusion

use of two-Delta converter control of the centrifuges, has the following characteristics:
(1) low-speed torque, a smooth start;
(2) energy-saving, shared bus dual two-inverter motor drive in the horizontal screw on the wider use of centrifuges, that is, Lord, the vice-motor with a common frequency converter drive, with its DC bus and then in an appropriate manner, the better To address this issue in the growing energy shortage, there is special significance;
(3) to facilitate adjustment, the broader terms of reference;
(4) simplify the mechanical structure, reducing the failure rate.