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Medium-frequency power supply The heat generation is closely related to energy-saving issues. How is the heat generation of a medium-frequency power supply calculated?

You can estimate based on the power of the medium-frequency power supply. A rough estimation formula is: Power supply power × 0.15 × 860,800 kW. What cross-sectional area of copper-core cable should be selected for a medium-frequency induction furnace?

With a power rating of 800 kW, is it a three-phase or single-phase system? And what is the voltage? Only then can we determine the current and subsequently select the appropriate cable!

Answer: The power per phase is 800/3 = 266 kW, and the current per phase is 266 kW / 380 V = 700 A. Given that the load current per square millimeter of copper wire ranges from 6 to 8 A, the required cross-sectional area of the copper wire is around 100 square millimeters—corresponding to a three-phase four-wire power cable with a diameter of approximately 11 mm and rated for voltages above 500 V. Similarly, the intermediate-frequency current is 800 kW / 1500 V = 533 A; therefore, the cable can be designed at a rate of 10 A per square millimeter. Consequently, the outgoing cables should use power cables with a cross-section of no less than 50 square millimeters and rated for voltages above 2000 V! What are the steps involved in adjusting the trigger pulses for the rectifier in a thyristor-based intermediate-frequency power supply?

Close Control circuit power ( At this point, the main power supply is disconnected. Check whether the transformers in each control section are functioning properly and look for signs of short circuits, overheating, or smoking. If the transformers appear normal, reconnect the regulated power supply and verify that its output voltage meets the specified requirements. Then, sequentially connect the printed circuit boards for the rectifier triggering circuit, the regulating circuit, the protection circuit, and the inverter triggering circuit. Observe the corresponding control circuit meter readings or the status of the light-emitting diodes to determine whether each circuit is operating correctly. Use an oscilloscope to examine the trigger pulse waveforms between the gate and cathode of each thyristor in the rectifier circuit. The inspection should proceed in the order of thyristors numbered 1 through 6. For each pair of thyristors in sequence, the phase difference between the leading edges of their two trigger pulses (in the case of dual-pulse triggering, it should be the leading edge between the first two pulses) should be 60°. Also, check whether the width of the trigger pulses meets the required specifications. Furthermore, if the average value of the amplitudes of all trigger pulses is twice the expected value, you should verify whether the gate circuit of that particular thyristor is open-circuited or whether the gate resistance is excessively high. If either condition exists, replace the thyristor. If the amplitude of the trigger pulse for a specific thyristor is unusually low, you should also inspect the primary and secondary sides of the pulse transformer as well as the power amplifier transistor. A short circuit in the anti-interference capacitor or the reverse-parallel diode in the secondary-side circuit of the pulse transformer can also cause extremely low or absent gate pulses. When checking the trigger pulses, make sure to measure them directly at the gate terminals of the thyristors.