Thyristors and diodes are widely used in all kinds of power electronic devices. In many cases, field service personnel and maintenance personnel need to detect the devices and judge their performance. For device manufacturing enterprises, the detection of devices needs to use high-voltage blocking tester, on-state characteristic tester, dynamic characteristic tester and other professional equipment. In general, the device user or the use of the field is not these expensive test equipment. In this paper, a simple device detection method is recommended to field service personnel and maintenance personnel to roughly judge the quality of the device.
One ，Use the rough judgment method of multimeter
Usually the most commonly used detection tool in the user's field is a multimeter, and many users are also accustomed to using a multimeter to judge the quality of the device. In some cases, it is also possible to detect damaged components with a multimeter. If the gate of the thyristor is open, the cathode resistance RGK can be detected by a multimeter. Gate short circuit can be detected to the cathode resistance RGK of zero (or less than 5W). When the device is completely broken down, the resistance value of A and K poles can be determined by using a multimeter. However, when the device blocking voltage is damaged and not completely broken down, the multimeter cannot detect it. In addition, due to the dispersion of the parameters of A good device, there will be a large difference in the resistance value of A and K detected by a multimeter, which will also allow users to make wrong judgments. Therefore, we recommend that users can use a multimeter to carry out some rough detection of the device, and generally do not recommend that users use a multimeter to judge the quality of the device.
Two, Recommended simple detection protocol
Often, the most important thing field service personnel and maintenance personnel need to understand is the blocking voltage capability of the device and the gate triggering performance of the thyristor. According to the equipment site conditions. The DUT is the device under test. When the DUT block voltage is about 1000V (greater than 800V), the AC 380V power supply can be used for test. In some cases with 660V AC power supply, when the DUT block voltage is about 2000V (must be greater than 1200V), AC 660V power supply can be used for testing. D1 can use 1-5A, withstand voltage more than 1000V diode 3 series. LAMP is a test indicator. It should be noted that the rated voltage of the lamp should be matched with the incoming AC voltage. If a 220V lamp is used, multiple lamps can be connected in series according to the incoming voltage. When the device under test is a diode, connect the two devices to the circuit as shown in dotted lines, without the need to connect the resistor R and switch SW2.
When testing the thyristor, switch SW1 first. If the indicator is on, it indicates that the device has been broken down or the blocking voltage is not enough. If the indicator is off, the blocking voltage of the device is normal. If you press SW2, the indicator is on, release the button, and the indicator is off, it indicates that the gate triggering performance of the device is normal. If you press button SW2 and the indicator is not on, it indicates that the device gate is damaged.
For the diode, when testing, turn on the switch SW1, if the indicator light is not on, it indicates that the reverse voltage of the two devices is normal. If the indicator is on, it indicates that one or both reverse voltages of the two measured devices are damaged. Replace the devices for further judgment.
3. Notice
a. The basic idea of the detection method recommended in this paper is to let the device be tested under the actual voltage environment, and the user must ensure that the blocking voltage of the device under test is higher than the peak value of the incoming voltage during the detection, so as to avoid damage to the device during the test. b. For the flat panel device of Taiji Company, the user must use an appropriate fixture when testing, and exert A certain pressure on the two poles of the device A and K. Otherwise, it may cause misjudgment due to the lack of good contact within the device. c. When using a higher incoming voltage detection device, the operator must take safety measures to prevent electric shock accidents and ensure personal safety.