Introduction to Measuring Unidirectional Thyristors with a Digital Multimeter
Identification of Unidirectional Thyristor Performance
Unidirectional thyristor (SCR), formerly known as thyristor, is a controllable rectifier component. Its circuit symbol is shown in Figure 1, where A is the anode, K is the cathode, and G is the control electrode.
Identification of Unidirectional Thyristor Performance
Unidirectional thyristor (SCR), formerly known as thyristor, is a controllable rectifier component. Its circuit symbol is shown in Figure 1, where A is the anode, K is the cathode, and G is the control electrode.
(1) The discrimination electrode is fixed in contact with either electrode using a red meter rod, while the black meter rod contacts the other two electrodes separately. If it displays 0.2-0.8V at a time when it contacts one electrode and overflow when it contacts the other electrode, then the red meter rod is connected to G, the black meter rod is connected to A when overflow is displayed, and the other electrode is K. If the measured result is not the same as above, the red meter rod needs to be replaced with another electrode and the above steps repeated until the correct result is obtained.
(2) The trigger characteristic of the digital multimeter diode block can only provide a test current of about 1mA, so it can only be used to test the triggering ability of low-power unidirectional thyristors. The operation method is as follows: fix contact A with a red gauge rod and keep it unchanged, and contact K with a black gauge rod. At this time, overflow (off state) should be displayed. Next, touch G with the red gauge rod while keeping it connected to A. At this point, the displayed value is generally below 0.8V (indicating a conductive state). Immediately disconnect the red gauge rod from the control pole, and the conduction state will continue to be maintained. If this test is repeated multiple times, it indicates that the tube triggers sensitively and reliably. This method is only applicable to tubes that maintain low current.
