Typical on-state voltage drop of a conducting thyristor When an SCR is in the on state and conducting rated current, the approximate voltage drop across it is:
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Aabout 1 V
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Babout 10 V
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Cabout 100 V
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Dabout 0.1 V
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Eabout 50 V
Answer
Correct Answer: about 1 V
Explanation
Introduction / Context:The on-state drop of power devices directly influences conduction losses and heat sink sizing. For SCRs, the drop is relatively low compared with transistors at similar currents.
Given Data / Assumptions:
- Thyristor in full conduction (latch-on), steady current.
- Typical industrial devices at nominal current and temperature.
Concept / Approach:SCRs exhibit a quasi-constant on-state drop, often around 1 to 2 V depending on current and temperature, due to their PNPN conduction characteristics.
Step-by-Step Solution:Select the closest nominal value used for loss estimates → ~1 V (sometimes 1–2 V).Rule out obviously excessive values like 10 V or more at rated current.
Verification / Alternative check:Datasheets list V_T(on) typically in the 1–2 V range for rated currents.
Why Other Options Are Wrong:10–100 V: Would cause huge losses; not realistic for a conducting SCR.0.1 V: Too small for SCR technology; closer to low-Rds(on) MOSFETs at modest current.
Common Pitfalls:Using a single fixed value; real devices vary with current and junction temperature.
Final Answer:about 1 V