Question 71 : In HVDC transmission lines
1. both the stations operate as an inverter
2. both the stations operate as a converter
3. one acts as a converter and other as an inverter
4. depends upon the type of the load
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Question 72 : _________ is used for critical loads where temporary power failure can cause a great deal of inconvenience.
1. SMPS
2. UPS
3. MPS
4. RCCB
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Question 73 : The single phase mid-point type cycloconverter uses __________ number of SCRs.
1. 4
2. 8
3. 6
4. none of the mentioned
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Question 74 : SMPS is used for
1. obtaining controlled ac power supply
2. obtaining controlled dc power supply
3. storage of dc power
4. switch from one source to another
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Question 75 : Solid State Relays (SSRs) have a
1. coil and contact arrangement
2. optocoupler
3. scr
4. none of the mentioned
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Question 76 : In three phase cycloconverters, the reduction factor is given by
1. input frequency/output frequency
2. (input frequency/output frequency) ^-1
3. (input frequency/output frequency) ^-1/2
4. (input frequency/output frequency) ^1/2
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Question 77 : No discontinuity is observed in case of
1. short break static UPS configuration
2. long break static UPS configuration
3. no break static UPS configuration
4. rotating type UPS configuration
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Question 78 : The reverse recovery time of a diode is t_rr = 3 μs and the rate of fall of the diode current (di/dt) = 30 A/μs. Determine the storage charge.
1. 145 μs
2. 135 μs
3. 0
4. none of the mentioned
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Question 79 : For high power applications _________ are used as static switches whereas for low power applications __________ are used.
1. Transistors, SCRs
2. SCRs, transistors
3. Diodes, transistors
4. SCRs, diodes
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Question 80 : Determine the loss in the snubber circuit, if C = 0.545 μF and supply is 200 V, 10 kHz.
1. 233 W
2. 133 W
3. 333 W
4. 233 W
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