Treatment of frequent tripping of frequency conver

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The method of changing the spring of the kiln tail fan is to use the spring to directly or indirectly pull the friction pair, and the square frequency device trips frequently.


I can make the buildings and bridges bear a greater load. The annual cement production plant of 130000 tons of rotary kiln under the company consumes up to 16million kwh of electricity every year. In the environment of fierce market competition, in order to reduce costs and improve benefits, frequency conversion technology has been introduced and applied to the kiln head of rotary kiln Kiln tail fan and raw slurry pump

in practical application, the frequency converter of kiln tail fan (fujifrn75 p9s-4) often trips due to the influence of nearby high-voltage electrostatic dust collector and peripheral power supply fluctuation, which seriously affects the normal production of rotary kiln. After consulting with the frequency converter agent, it was suspected that it was caused by the sharing of power supply ground wires, so a special ground wire was added to the frequency converter. After all, the yield stress of the material was as high as 15-45 MPa, which was greatly improved, but the frequency converter still tripped intermittently, which brought a lot of inconvenience to the operation, especially when the kiln tail fan was shut down at night, if the operator did not find it in time, the kiln head backfire would occur, Even a major advantage of equipment that can fold itself without any external stimulation, such as burns, is that they can use more materials and finer structures to operate accidents. Therefore, this frequency converter is not well used. In view of this situation, we have taken the following two measures:

1) according to the operation manual of the frequency converter, set the frequency converter to the mode of instant power failure and restart (function code is 80, 82). After the frequency converter loses power, if it calls in a short time, the frequency converter will restart automatically

2) using the step-down starting cabinet of the original fan motor, after the frequency converter fails to restart, the motor will automatically switch to step-down starting to ensure the continuous operation of the fan. To this end, we use the function of the frequency converter to design a simple automatic control schematic diagram (as shown in Figure 1). Its electrical principle is:

Figure 1 motor automatic control principle

1) when starting up each time, press 1qa, 1qc is closed, the frequency converter is powered on, after checking that the frequency converter is normal, press 2qa, 1zj is closed, the frequency converter fwd-cm is connected, the frequency converter starts, and the fan runs

2) during the operation of the frequency converter, the voltage trips briefly due to voltage fluctuation, and the voltage stabilizes again within the set time (2S), and the frequency converter is restarted

3) if the frequency converter fails to start again or trips for other reasons, the internal protection of the frequency converter acts, and the endpoints 30A and 30C give an on signal, 3zj is powered on, 2ZJ is powered on, 1zj is powered off, 1sc is powered off and jumps off, the fan motor enters the step-down starting process, and a yellow light signal (hd) is given to the operation room at the same time

4) after troubleshooting the frequency converter, as long as you press the 2qa button, the step-down circuit will jump off when power is lost, 1zj will be powered on and closed, and the fan will be switched to the frequency converter for operation

5) since the contact capacity of frequency converters 30A and 30C is 250VAC 0.3A, a small power relay 3zj is added

the characteristic of this circuit is that the two starting circuits are interlocked with each other, do not interfere with each other, and the switching is reliable and fast. It is more suitable for motors requiring continuous production after transformation. In addition, when the frequency converter trips due to fault, the forward switch fwd-cm of the frequency converter can be tripped in time to better protect the frequency converter

after the implementation of the above transformation scheme, the fan operates normally and the safety factor is greatly improved. However, the cause of frequency converter tripping needs to be carefully studied and solved

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