Application of FD5000 Series Medium Voltage Drive in Powder Discharging Machine

1.Overview
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(1) Due to the heavy load of the circulating pump and the large starting torque, the full pressure direct starting mode is adopted, the starting current reaches 4~6 times of the rated current, and the impact on the whole electrical system is relatively large, which brings adverse effects on the smooth operation of the electrical system;

(2) in order to ensure the pressure and flow in different water conditions, need to open three pump, but flow is rich, in order to ensure the stability of network pressure and flow, have to assign professional production operators patrol network pressure, and adjust the valve opening and pressure drainage, not only cause the production operators of labor intensity, and wasted a lot of precious water resources, does not conform to the concept of the water conservation in our country;

(3) When the water demand is small, the motor must also run at full pressure and full speed, resulting in the phenomenon of "big horse pulled cart", generating a large amount of power waste, and at the same time, resulting in the reduction of power factor;

(4) the motor has been in full speed operation, cause motor bearing easy to heat and wear phenomenon, summer, motor bearing temperature up to 85℃, accelerated the destruction of bearing grease, wear bearing must be replaced in time, accelerate the motor maintenance speed, greatly increased the operating costs of the system;

(5) The wear of the motor bearing also causes the noise of the whole system operation, which has adverse effects on the health of employees.

2.Implementation plans

In order to solve the above problems, in the subsequent technical transformation, the technicians equipped the high voltage frequency conversion control system. A pressure transmitter is installed on the circulating water pipe network to convert the pressure of the circulating water pipe network into 4-20 mA signal to the frequency converter. Comparing the signal with the set pressure converter automatically adjusts the output speed of the frequency converter, so as to realize the automatic closed-loop control of constant pressure water supply.

After the transformation, the manual start and the automatic frequency conversion operation are required. The control mode is one drag and one drag, and the primary circuit is composed of incoming line cabinet (bypass cabinet), transformer cabinet, frequency conversion unit cabinet and operation control cabinet. When the bypass cabinet is in the maintenance process of the frequency converter or when the frequency converter fails, the motor is automatically put into the power frequency power grid operation to ensure that the production is not affected. During the frequency conversion operation, the frequency converter provides comprehensive protection for the motor. The operation mode of the inverter is open loop operation, which tracks and controls the circulating water pressure in operation.

Frequency conversion control automatic bypass cabinet after providing bypass scheme is as follows: according to the preliminary communication with the user, according to the requirements of user use recommend a drag a manual bypass, the main wiring mode as shown below: frequency conversion speed control system by the user switch, manual switch bypass cabinet, FD5000 series medium voltage drive, high voltage motor. One manual switch bypass cabinet is composed of three high voltage disconnecting switches QS1~QS3. The manual bypass cabinet is designed in strict accordance with the requirements of "five prevention" interlocking. The inverter output QS2 and the bypass high voltage disconnecting switch QS3 cannot be closed at the same time, which can fully ensure the safe operation of the frequency conversion speed control system.

3.Application advantages

FD5000 series medium voltage drive uses high-speed DSP as the central processor, faster operation speed and more accurate control.

Flying car start function. Can recognize the speed of the motor and start directly when the motor keeps turning.

Speed start. During the operation process, the high voltage instantaneous power drop is restored within 3s, and the high voltage frequency converter does not stop. After the high voltage recovery, the frequency conversion automatically runs to the frequency before the power drop.
Line voltage automatic equalization technology (star point drift technology).