What material is used to construct the auxiliary or ignition anode in a mercury arc rectifier____________?
Show answer Hide answer
Answer: B. boron carbide
Explanation
Boron carbide provides the necessary chemical and thermal stability required during continuous ignition. Refractory materials successfully withstand intense heat generated within industrial mercury arc rectifier units. Choosing boron carbide prevents rapid degradation of auxiliary anodes under harsh operating conditions. Mercury arc rectifiers require specialized internal components to initiate and maintain electrical arcs reliably. Ignition anodes help start the conduction process inside evacuated glass or steel rectifier bulbs. Refractory compounds are engineered to endure extreme temperatures without melting or chemically breaking down.
Heavy industrial power conversion equipment relies heavily on durable materials for long operational lifespans. Engineers select specialized ceramics when designing high-power electrical switching and rectification systems. Proper ignition reliability ensures uninterrupted conversion from alternating current to direct current. Graphite is commonly used for main anodes rather than the specialized ignition or auxiliary components. Aluminium and copper lack the necessary high melting points and refractory characteristics needed here. Alternative metals would quickly erode under the intense bombardment of mercury ions and electrons.
- Subject
- Engineering
- Category
- Electrical Engineering
- Topic
- —
- Difficulty
- medium
Related questions
Q1. What is the maximum continuous DC output rating typically achieved by glass bulb rectifier units_____________?
Show answer Hide answer
Answer: E. 500 A at 500 V
Standard glass bulb rectifier units typically achieve maximum continuous DC output ratings around 500 A at 500 V. This rating matches the safe thermal and electrical limits of standard glass envelope designs. Exceeding 5...
Q2. When steam is initially superheated, the ratio of exit pressure to inlet pressure yielding maximum mass flow per unit area through a nozzle is__________?
Show answer Hide answer
Answer: C. 0.5457
For initially superheated steam flowing through a converging diverging nozzle, the critical pressure ratio is approximately 0.5457. This specific ratio yields the maximum possible mass flow rate per unit area, also known...
Q3. What efficiency range is achievable with selenium rectifiers_______ to _______ percent?
Show answer Hide answer
Answer: D. 75, 85
Selenium rectifiers typically operate with an efficiency range of 75 to 85 percent. Internal semiconductor junction resistance causes minor power losses during AC to DC conversion. This efficiency level made selenium rec...
Q4. Up to what high ambient temperature can a selenium rectifier function____________?
Show answer Hide answer
Answer: D. 75°C
Selenium rectifiers possess robust material properties allowing reliable operation up to seventy five degrees Celsius. Exceeding seventy five degrees Celsius can cause irreversible damage to the selenium semiconductor la...
Q5. What factors determine the internal efficiency of a mercury arc rectifier___________?
Show answer Hide answer
Answer: A. voltage only
The internal voltage drop across the arc in a mercury arc rectifier remains nearly constant regardless of the operating current level. Since efficiency depends on the ratio of output voltage to total voltage including th...
Q6. Armature currents flowing within a running rotary converter are______________?
Show answer Hide answer
Answer: C. partly a.c. and partly d.c.
The armature winding of a running rotary converter carries alternating current supplied from the input. Simultaneously, direct current is delivered to the external circuit through the commutator and brushes. Superimposin...