Thyristor Semiconductor Products Page 52 Thyristor

2014 Littelfuse, Inc. Specifications are subject to change without notice. Revised: 12/14/14 Teccor brand Thyristors AN1006 Procedure 4: V TM To measure the V TM parameter: 1. Set Terminal Selector to Step Generator-Emitter Grounded. 2. Set Polarity to (+). 3. Set Step/Offset Amplitude to twice the maximum I GT rating of the device (to ensure the device turns on). For sensitive SCRs, set to 2 mA. 4. Set Max Peak Volts to 15 V. ( 16 V on 370) 5. Set Offset by depressing 0 (zero). 6. Set Rate by depressing Norm. 7. Set Step Family by depressing Rep (repetitive). 8. Set Mode to DC . 9. Set Horizontal knob to 0.5 V/DIV. 10. Set Power Dissipation to 220 W ( 100 W on 577 ). 11. Set Number of Steps to 1 . (Set steps to 0 (zero) on 370.) 12. Set Vertical knob to a sufficient setting to allow the viewing of 2 times the I T(RMS) rating of the device (I T(peak) ) on CRT. Before continuing with testing, note the following: (1) Due to the excessive amount of power that can be generated in this test, only parts with an I T(RMS) rating of 6 A or less should be tested on standard curve tracer. If testing devices above 6 A, a Tektronix model 176 high-current module is required. (2) A Kelvin test fixture is required for this test. If a Kelvin fixture is not used, an error in measurement of V TM will result due to voltage drop in the fixture. If a Kelvin fixture is not available, Figure AN1006.3 shows necessary information to wire a test fixture with Kelvin connectors. 13. Set Left-Right Terminal Jack Selector to correspond with the location of the test fixture. 14. Increase Variable Collector Supply Voltage until current reaches rated I T(peak) , which is twice the I T(RMS) rating of theSCR under test. Note: Model 370 current is limited to 10 A. WARNING: Limit test time to 15 seconds maximum after the Variable Collector Supply has been set to I T(peak) , After the Variable Collector Supply Voltage has been set to I T(peak) , the test time can automatically be shortened by changing Step Family from repetitive to single by depressing the Single button. To measure V TM , follow along horizontal scale to the point where the trace crosses the I T(peak) value. The distance from the left-hand side of scale to the intersection point is the V TM 500 mV V E R T H O R I Z S T E P I PK V TM 2 A 100 mA 20 Figure AN1006.7 V TM = 1.15 V at I T(peak) = 12 A Procedure 5: I H To measure the I H parameter: 1. Set Polarity to (+). 2. Set Power Dissipation to 2.2 W. ( 2 W on 370) 3. Set Max Peak Volts to 75 V. (80 V on 370) 4. Set Mode to DC. 5. Set Horizontal knob to Step Generator. 6. Set Vertical knob to approximately 10 percent of the maximum I H specified. Note: Due to large variation of holding current values, the scale may have to be adjusted to observe holding current. 7. Set Number of Steps to 1. 8. Set Offset by depressing 0 (zero). (Press Aid and Oppose at the same time on 370.) 9. Set Step/Offset Amplitude to twice the maximum I GT of the device. 10. Set Terminal Selector to Step Generator-Emitter Grounded. 11. Set Step Family by depressing Single . 12. Set Left-Right Terminal Jack Selector to correspond with location of test fixture. 13. Increase Variable Collector Supply Voltage to maximum position ( 100 ). 14. Set Step Family by depressing Single . (This could possibly cause the dot on CRT to disappear, depending on the vertical scale selected.) 15. Change Terminal Selector from Step Generator- Emitter Grounded to Open Base-Emitter Grounded . 16. Decrease Variable Collector Supply Voltage to the point where the line on the CRT changes to a dot. The position of the beginning point of the line, just before the line becomes a dot, represents the holding current value. (Figure AN1006.8) Thyristor and Rectifier Testing Using Curve Tracers (continued)

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