What is the cathode and anode of the thyristor?

Admin · 1 What is the cathode and anode of the thyristor? Wed Sep 16, 2020 5:39 am

Admin

Posts : 6693
Join date : 2019-05-10

Thyristors are divided into unidirectional <a href="https://www.pst888.com/power-thyristors" target="_blank">thyristor</a>s and bidirectional thyristors. The following is the Positioning of these two kinds of thyristors.Method for the detection of the cathode and anode and the trigger pole of a thyristor(1) detection of unidirectional thyristor1. According to the structure of the common thyristor, there is A PN junction between the gate electrode G and the cathode electrode K, which is characterized by one-way conduction, while there are two PN junctions in series between the anode A and the gate electrode. Therefore, by using the multimeter R×100A or R×1k can measure the resistance between the pins of the common thyristor, namely, three electrodes can be determined. The specific method is: the multimeter black meter pen either connected to the thyristor a certain pole, the red meter pen in turn to touch the other two electrodes. If a resistance measurement results for several thousand ohms Ω (k), and the other a value for a few hundred ohms (Ω),Can determine that the black pen is connected to the gate G. In the measurement of resistance of several hundred ohms, the red marker is connected to cathode K, while in the measurement of resistance of several thousand ohms, the red marker is connected to anode A. If the resistance measured twice is large,It indicates that what the black watch pen connects is not gate G, and other electrodes should be tested with the same method until three electrodes are found.The positive and reverse resistances between any two feet can also be measured. If the positive and reverse resistances are close to infinity, then the two poles are anode A and cathode K, and the other leg is gate G.Ordinary thyristors can also be used to determine the electrodes based on their encapsulation.Bolt type common thyristor bolt end is anode A, the thin lead end is gate G, the thick lead end is cathode K.The lead end of the flat type common thyristor is gate G, the flat end is anode A, and the other end is cathode K.A common thyristor enclosed in A metal case (TO - 3) with A case of anode A.The middle pin of the ordinary thyristor (TO - 220) is anode A, and it is usually connected with its own cooling fin.2. The positive and reverse resistances between anode A and cathode K of the ordinary transistor are measured with the multimeter R×1k, which should be infinite (∞) in normal time. If the positive and reverse resistances between A and K are measured to be zero or small, indicating the internal breakdown of the thyristor short circuit or leakage.The positive and reverse resistance values between gate G and cathode K should be measured. When normal, the positive and reverse resistance values should be similar to those of diode (the actual measurement results are smaller than those of ordinary diode), that is, the forward resistance values are smaller(less than 2 k Ω), reverse resistance larger Ω (greater than 80 k). If the two measured resistance values are large or small, it means that the thyristor G, K poles open or short circuit. If the positive and negative resistance values are equal or close to each other, it means that the thyristor has failed, and the PN junction between its G and K terminals has lost its one-way conductive effect.Measuring anodic A and gate G, the positive and reverse resistance between the normal both resistance should be several hundred thousand ohms Ω (k) or infinity, if there is, the reverse is not the same as the resistance value (one-way conductive similar diode), is between G, A pole in the series of reverse one of the two PN junction has breakdown short circuit.3. For common thyristors with low power (operating current below 5A), multimeter R×1 can be used for measurement. When measuring, the black pen is connected to anode A and the red pen is connected to cathode K. At this time, the needle is still and the display resistance value is infinite (∞). The anode A of the thyristor is short-circuited with tweezers or wires, which is equivalent to applying A forward trigger voltage to the g-pole. At this time, if the resistance value is several ohms to several tens of ohms (the specific resistance value will vary according to the type of thyristor), it indicates that the thyristor is conducting due to the forward trigger. Then disconnect the connection between the a-pole and the g-pole (the meter pen on the a-pole and k-pole does not move, and only the g-pole trigger voltage is broken). If the indicator value of the meter needle still remains at A position of several ohms to dozens of ohms, it indicates that the thyristor has good triggering performance.In more than 5 a to the natural current, high power thyristor, because of its pressure drop on state VT, maintain current IH door trigger voltage VG are relatively large, multimeter R x 1 file provided by the current on the low side, thyristor cannot completely conduction, so the test on the black table when written down an 200 Ω concatenated adjustable resistance and 1 ~ 3 section 1.5 V dry cell (depending on the capacity of the measured thyristor, its working current is larger than 100 a, applied 3 section 1.5 V dry cell), circuit, measured thyristor, VT for 6.3 V HL indicator light (the flashlamp flashlight), GB is 6V power supply (4 1.5v dry batteries or 6V stabilized power supply can be used), S is the button, and R is the current limiting resistance.When button S is not connected, thyristor VT is in the blocking state, and the indicator HL is not on (if HL is on, VT breakdown or leakage damage will occur). After pressing button S (connect S to provide trigger voltage for gate G of thyristor VT), if the indicator HL is always on, it indicates that thyristor has good triggering ability. If the indicator light is low in brightness, it indicates poor performance of the thyristor and large on-off voltage drop (normally, the on-off voltage drop should be about 1V). If the indicator light is on when the button S is connected, and the indicator light is off when the button is disconnected, it indicates that the thyristor has been damaged and the triggering performance is poor.(2) bidirectional thyristor detection1. Distinguish the positive and reverse resistance values between the three pins of the bidirectional thyristor measured with the multimeter R×1 or R×10 for each electrode. If one pin is not connected with the other two feet, the foot is the main electrode T2.After the T2 pole is found, the remaining two legs are the main electrode T1 and the gate electrode G3. Measuring the positive and negative resistance between the two legs will give you two smaller resistance values. In a measurement with a small resistance value (about a few dozen ohms), the black pen is connected to the main electrode T1, and the red pen is connected to the gate electrode G.One end of the bolt type bidirectional thyristor is the main electrode T2, the thinner lead end is gate G, and the thicker lead end is the main electrode T1.Metal encapsulation (TO - 3) bidirectional thyristor shell for main electrode T2.The intermediate pin of the laminate (TO -- 220) is the main electrode T2, which is usually connected TO its own small heat sink. 2. The positive and negative resistance values between the main electrode T1 and the main electrode T2, and between the main electrode T2 and the gate electrode G of the bidirectional thyristor should be measured with the multimeter R×1 or R×10, which should be close to infinity under normal conditions. If the measured resistance values are all small, it indicates that the thyristor has been broken down between the electrodes or a leakage short circuit. Measuring the electrode between T1 and gate G is, reverse resistance, normal should be (Ω) in a few ohms to one hundred ohms (Ω) (black pens and meet the T1, red pens and meet G extremely, measured forward resistance than reverse resistance slightly smaller). If the positive and negative resistance values between T1 pole and G pole are both infinite, it indicates that the thyristor has been damaged open-circuit. 3. For small power bidirectional thyristors with operating current below 8A, the multimeter R×1 level can be used for direct measurement. When measuring the black pens and answer the first main electrode T2, T1 red pens and connect the main electrode, and then use tweezers to T2 extremely short circuit, and gate G to G and normal polarity trigger signal, if the measured resistance from infinity to a dozen ohms (Ω), explain the thyristor has been triggered conduction, conduction direction for T2 and T1. Then connect the black stylus to the main electrode T1, and the red stylus to the main electrode T2. Use tweezers to short circuit the T2 pole and gate G. When G pole is added with a negative polarity trigger signal, the measured resistance value should be changed from infinity to more than ten ohms, indicating that the thyristor has been triggered on and the conduction direction is T1→T2. If the g-pole is disconnected after the thyristor is triggered and the resistance between T2 and T1 cannot maintain the low resistance conduction state and the resistance value becomes infinite, it indicates that the bidirectional thyristor has poor performance or been damaged. If a positive (or negative) polarity trigger signal is added to G pole, the thyristor is still not conducting (the positive and reverse resistance between T1 and T2 is still infinite), it means that the thyristor has been damaged and has no triggering and conducting ability. For the working current of the medium and high power bidirectional thyristor with more than 8A, when measuring its triggering capacity, it can first connect 1 to 3 1.5v dry batteries in series on a meter pen of the multimeter, and then use R×1 to measure it according to the above method. For the bidirectional thyristor with a withstand voltage of more than 400V, 220V ac voltage can also be used to test its triggering ability and performance. After the power plug is connected to the power supply, the bidirectional thyristor is in the cut-off state and the bulb is not on (if the light bulb is normally illuminated at this time, it means that the T1 and T2 poles of the thyristor under test have been broken down and short-circuited; If the light bulb is dim, it means the thyristor under test is damaged due to leakage. Press button S to provide the trigger voltage signal for gate G of the thyristor. When normal, the thyristor should be triggered immediately and the bulb should emit normal light. If the bulb does not emit light, the open circuit inside the thyristor under test is damaged. If the bulb is on when the button S is pressed, and the bulb is off when the button S is released, it indicates that the thyristor under test has poor triggering performance.

What is the cathode and anode of the thyristor?

1 What is the cathode and anode of the thyristor? Wed Sep 16, 2020 5:39 am

Admin