Bake the furnace for a period of time, the shutdown is not good to start
Failure phenomenon: for the new melting furnace or knotting of the transmittance furnace, at the beginning of the baking furnace can be started, the voltage can be increased to reach the maximum value, but baking furnace after a period of time, the shutdown is no longer good to start up, get up after the voltage can not be higher, and sometimes their own stop vibration or overcurrent.
Failure analysis and treatment: most of this failure is a problem between the turns of the inductor.
- For just knotting a good melting furnace, due to knotting material in the oven will produce a lot of water, so that the inductor turns gathered a large number of water droplets, resulting in a reduction in insulation between the turns, the oven voltage should not be very high at this time, to be dried and then increase the voltage.
- Some inductor coils are directly knotted with knotting material without being dipped in insulating varnish, and this type of furnace requires even more attention to how much moisture is present in the oven when baking.
- Some knotting of the transmittance furnace after a period of time, knotting material will appear tiny gaps, at this time, if the inductor insulation is not handled properly, there will be a small amount of oxidized skin into the inductor ring between the turns, resulting in a short-circuit between the turns, prone to overcurrent phenomenon. It is best to wrap the inductor coil with mica tape and then dip paint, drying, and finally knotting.
Reactor is loud and dull, unstable and trembling when boosting voltage
Fault phenomenon: the equipment can be started, but the voltage rise is not high, the reactor is particularly loud and dull, the voltage rise is very unstable, there is trembling. From time to time there are overcurrent or overvoltage faults, and sometimes even burned out the inverter tube, but disconnect the rectifier part of the inverter circuit is good.
Failure analysis and handling: most of this failure is a problem with the reactor.
- The inductance of the reactor is larger than normal, the magnetic circuit is saturated, it can’t play the role of renewed current filtering, and it can’t isolate the current between the AC and DC ends, and the number of turns of the reactor coil is more than normal.
- Reactor air gap plate is thinner than normal, inductance becomes larger, this time to thicken the air gap plate.
- There is water seepage between the turns of the coil of the reactor, and the insulation between the turns is reduced to the phenomenon of ignition discharge.
After the DC voltage rises above 500V, the DC voltage drops instead
Fault phenomenon: start and run normally, when the DC voltage rises to more than 500V, DC voltage instead of falling, fluctuations, and even overcurrent, sometimes burned off the fast fuse.
Failure analysis and treatment: this is the rectifier phase shift circuit:
- The zero wire on the control board is not connected. Some of the synchronization signal circuits on the control board require a zero wire, and if it is missing, there will be a phase shift deviation and the conduction angle α will exceed 0°, resulting in the phenomenon described above.
- The user has not connected the zero wire to the cabinet or the zero wire is falsely connected.
- There is a problem with the w4 potentiometer (150° adjustment) in the rectifier circuit, and when it is over-adjusted, the conduction angle α exceeds 0°. Sometimes when there is a problem with the front end feed circuit on the control board, the conduction angle α exceeds 0° as well.
Easy to over-voltage when boosting, or over-voltage and over-current at the same time
Fault phenomenon: easy to start, but easy to over-voltage when rising voltage, sometimes over-voltage and over-current at the same time.
Failure analysis and treatment are as follows.
- Easy overvoltage at startup, indicating that the inverter lead angle is too large, resulting in inverter burr voltage is too high, easy to make the overvoltage protection action. In the frequency sweeping circuit, after the over-voltage has to make the inverter bridge through the discharge function, at this time, if the current is also large, the over-current protection will also act.
- The main circuit inside the power supply cabinet has a false connection, reduced insulation, and firing.
- Load coil or capacitor has a false connection, reduced insulation, or firing.
- Inverter thyristor triggering with unreliable factors, loose wiring or gates
What is the reason for the high frequency after IF startup
Failure phenomenon: can start, start successfully after the frequency is much higher than the original, sometimes bad start.
Failure analysis and treatment: This is mostly a load problem.
- There is a short circuit between the turns of the load coil, and there may be a lap between the wires or conductive iron filings or copper wires.
- Load capacitors with posts open, or capacitor connecting wires with severe firing, resulting in internal capacity changes.
What is the reason for burning IF transformers
Failure phenomenon: intermediate frequency transformer burned out, replace the start-up equipment still burned out the intermediate frequency transformer.
Failure analysis and handling: this failure is common in the use of boost load equipment, mainly because of the discharge inductor false open circuit caused by.
- In the step-up load, series capacitor bank and shunt capacitor bank voltage can not be absolutely the same, in the two groups of compensation capacitors discharge, due to the end voltage is not the same, the length of its discharge time is not the same, then the high voltage discharge time is slow, and this group of capacitors has not been completely discharged to complete the charging process begins again, in this capacitor bank on the accumulation of DC charge, these DC charge to be released through the discharge These DC charges have to be released through the discharge sense, if the discharge sense is open circuit, the DC charge accumulated on the capacitor will be released through the IF transformer, due to the capacity of the IF transformer is very small, it can not withstand such a large current flow, causing the IF transformer to burn out.