How to distinguish between bidirectional and unidirectional thyristor

How to distinguish between bidirectional and unidirectional thyristors

thyristor is equivalent to a controllable diode. When a certain voltage is applied to the control electrode, the cathode and anode conduct.

thyristor are divided into two types: unidirectional thyristor and bidirectional thyristor, both of which have three electrodes. Unidirectional thyristor has a cathode (K), an anode (A), and a control electrode (G). Bidirectional thyristor is equivalent to two single thyristor connected in reverse parallel. One of the unidirectional silicon anodes is connected to the other cathode, and its output end is called the T2 electrode. One of the unidirectional silicon cathodes is connected to the other anode, and its output end is called the T2 electrode. The remaining is the control electrode (G). 1. Distinguishing between single and bidirectional thyristors: First, measure either pole, and if both the forward and reverse measuring pointers remain stationary (R × 1st gear), may be A, K or G, A pole (for unidirectional thyristor) or T2, T1 or T2, G pole (for bidirectional thyristor). If one of the measurements indicates tens to hundreds of ohms, it must be a unidirectional thyristor. And the red pen is connected to the K pole, the black pen is connected to the G pole, and the rest is connected to the A pole. If both the forward and reverse test instructions are tens to hundreds of ohms, it must be a bidirectional thyristor. Turn the knob to R again × 1 or R × During the 10th gear retest, if there must be a slightly higher resistance value, the red pen connected to the G pole, the black pen connected to the T1 pole, and the remaining T2 pole.

2. Performance difference: Turn the knob to R × 1st gear, for 1-6A unidirectional thyristor, the red pen is connected to the K pole, while the black pen is connected to both G and A poles. While keeping the black pen in the A pole state, the G pole is disconnected, and the pointer should indicate tens to 100 ohms. At this point, the thyristor has been triggered and the triggering voltage is low (or the triggering current is low). Then momentarily disconnect the A pole and then connect it, and the pointer should return to the ∞ position, indicating that the thyristor is in good condition.

For 1-6A bidirectional thyristor, the red pen is connected to T1 pole, while the black pen is connected to G and T2 poles simultaneously. While ensuring that the black pen does not detach from T2 pole, the G pole should be disconnected, and the pointer should indicate tens to more than 100 ohms (depending on the current size of the thyristor and the manufacturer). Then switch the two strokes and repeat the above steps to measure once. If the pointer indicates slightly more than ten to dozens of ohms than the previous one, it indicates that the thyristor is in good condition and the triggering voltage (or current) is small. If the G pole is disconnected while keeping the A or T2 poles connected, and the pointer immediately returns to the ∞ position, it indicates that the thyristor triggering current is too high or damaged. Further measurement can be carried out according to the method shown in Figure 2. For unidirectional thyristors, if the switch K is closed, the light should light up, but if the switch K is turned off, the light should still remain on. Otherwise, it indicates that the thyristors are damaged.

For bidirectional thyristor, when the switch K is closed, the light should light up, and when the switch K is turned off, the light should remain on. Then reverse connect the battery and repeat the above steps, all of which should be the same result to indicate that it is good. Otherwise, it indicates that the device has been damaged.

thyristor is equivalent to a controllable diode. When a certain voltage is applied to the control electrode, the cathode and anode conduct.

Thyristors are divided into two types: unidirectional thyristor and bidirectional thyristor, both of which have three electrodes. Unidirectional thyristor has a cathode (K), an anode (A), and a control electrode (G). Bidirectional thyristor is equivalent to two single thyristor connected in reverse parallel. One of the unidirectional silicon anodes is connected to the other cathode, and its output end is called the T2 electrode. One of the unidirectional silicon cathodes is connected to the other anode, and its output end is called the T2 electrode. The remaining is the control electrode (G). 1. Distinguishing between single and bidirectional thyristor: First, measure either pole, and if both the forward and reverse measuring pointers remain stationary (R × 1st gear), may be A, K or G, A pole (for unidirectional thyristor) or T2, T1 or T2, G pole (for bidirectional thyristor). If one of the measurements indicates tens to hundreds of ohms, it must be a unidirectional thyristor. And the red pen is connected to the K pole, the black pen is connected to the G pole, and the rest is connected to the A pole. If both the forward and reverse test instructions are tens to hundreds of ohms, it must be a bidirectional thyristor. Turn the knob to R again × 1 or R × During the 10th gear retest, if there must be a slightly higher resistance value, the red pen connected to the G pole, the black pen connected to the T1 pole, and the remaining T2 pole.

2. Performance difference: Turn the knob to R × 1st gear, for 1-6A unidirectional thyristor, the red pen is connected to the K pole, while the black pen is connected to both G and A poles. While keeping the black pen in the A pole state, the G pole is disconnected, and the pointer should indicate tens to 100 ohms. At this point, the thyristor has been triggered and the triggering voltage is low (or the triggering current is low). Then momentarily disconnect the A pole and then connect it, and the pointer should return to the ∞ position, indicating that the thyristor is in good condition.

For 1-6A bidirectional thyristor, the red pen is connected to T1 pole, while the black pen is connected to G and T2 poles simultaneously. While ensuring that the black pen does not detach from T2 pole, the G pole should be disconnected, and the pointer should indicate tens to more than 100 ohms (depending on the current size of the thyristor and the manufacturer). Then switch the two strokes and repeat the above steps to measure once. If the pointer indicates slightly more than ten to dozens of ohms than the previous one, it indicates that the thyristor is in good condition and the triggering voltage (or current) is small. If the G pole is disconnected while keeping the A or T2 poles connected, and the pointer immediately returns to the ∞ position, it indicates that the thyristor triggering current is too high or damaged. Further measurement can be carried out according to the method shown in Figure 2. For unidirectional thyristors, if the switch K is closed, the light should light up, but if the switch K is turned off, the light should still remain on. Otherwise, it indicates that the thyristors are damaged.

For bidirectional thyristor, when the switch K is closed, the light should light up, and when the switch K is turned off, the light should remain on. Then reverse connect the battery and repeat the above steps, all of which should be the same result to indicate that it is good. Otherwise, it indicates that the device has been damaged.