Induction melting furnace thyristor is also called thyristor rectifier. It is widely used in electronic circuits such as controllable rectification, AC voltage regulation, non-contact electronic switch, inverter and frequency conversion. Therefore, the induction The detection of the quality of the thyristor of the melting furnace is very important. I will summarize the method of detecting the thyristor of the induction melting furnace for you.
1. Rough judgment method using multimeter
Multimeters are commonly used as test tools on the user's site, and many users are also used to judging the quality of the device. In some cases, a multimeter can indeed detect a damaged device. If the thyristor door is open, a multimeter can detect the infinite resistance of the door-to-negative resistance RGK; if the door is short-circuited, it can detect that the door-to-negative resistance RGK is zero (or less than 5W). When the device finishes breakdown, it can be judged by testing the resistance values of A and K with a multimeter. But when the device blocking voltage is damaged and the breakdown is not completed, the multimeter cannot detect it. In addition, due to the parameter dispersion of a good device, the A and K resistance values detected by a multimeter will have a large difference, which will also cause the user to make a wrong judgment. Therefore, we recommend that users can use the multimeter to perform some rough tests on the device. Generally, it is not recommended that users use the multimeter to judge the quality of the device.
2. Simple detection scheme
In general, field service personnel and maintenance personnel need to understand the blocking voltage capability of the device and the gate triggering performance of the thyristor. According to the conditions on the equipment site, our simple detection scheme shown in the circuit.
DUT is the device under test. When the DUT blocking voltage is about 1000V (must be greater than 800V), you can use AC 380V power for testing; in some cases with 660V AC power, the DUT blocking voltage is about 2000V (must be greater than 1200V). When testing, you can use AC 660V power supply for testing. D1 can use 1-5A, three tubes with a voltage resistance of 1000V or more in series. LAMP is a detection indicator. Note that the rated voltage of the lamp must match the AC voltage of the incoming line. If a 220V bulb is used, multiple series can be used according to the incoming line voltage. When the device under test is two tubes, the two devices are connected to the circuit as shown by the dotted line, and it is not necessary to connect the resistor R and the switch SW2.
For the thyristor, close the switch SW1 first during the test. If the indicator light is on, it means that the device has been broken down or the blocking voltage is not enough. If the indicator light is off, it means that the device blocking voltage is normal. At this time, if you press the button SW2, the indicator light is on, release the button, and the indicator light is off, indicating that the device's door triggering performance is normal. If the button SW2 is pressed, the indicator does not light, indicating that the device door has been damaged.
For the diode, close the switch SW1 during the test. If the indicator light is off, the reverse voltage of the two devices is normal. If the indicator light is on, it means that one or two reverse voltages of two devices under test have been damaged, and the devices can be replaced for progress judgment.
3. Note
a. The basic idea of the detection method in this article is to allow the device to be evaluated under the actual voltage environment. The user must ensure that the block voltage of the device under test is higher than the peak voltage of the incoming line during the test, so as not to damage the device during the test.
b. For Taiwan-based flat-panel devices, the user must use a suitable fixture when testing, and apply a constant pressure to both devices A and K. Failure to do so may result in misjudgment due to poor internal contact of the device.
c. When using a higher line voltage detection device, the operator must take safety measures to prevent electric shock and ensure personal safety.
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