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192. The term used to measure the degree of utilization of SCRs connected in series & parallel is a) tuf b) string efficiency c) voltage/current utilization ratio d) rectification efficiency
Answer: b Explanation: String Efficiency = Rating of the whole string/(rating of one SCR x number of SCRs)
Answer: b
Explanation: String Efficiency = Rating of the whole string/(rating of one SCR x number
of SCRs)
See less191. SCRs are connected in parallel to fulfill the ___________ demand a) high voltage b) high current c) size d) efficiency
Answer: b Explanation: Number of devices connected in parallel can carry huge amounts of current.
Answer: b
Explanation: Number of devices connected in parallel can carry huge amounts of
current.
See less171. di/dt protection is provided to the thryistor by a) connecting an inductor in parallel across the load b) connecting an inductor in series with the load c) connecting an inductor in parallel across the gate terminal d) connecting an inductor in series with the gate
Answer: b Explanation: By placing the di/dt inductor (L) in series with the load, the change in the anode current can be limited to a small value.
Answer: b
Explanation: By placing the di/dt inductor (L) in series with the load, the change in the
anode current can be limited to a small value.
See less171. di/dt protection is provided to the thryistor by a) connecting an inductor in parallel across the load b) connecting an inductor in series with the load c) connecting an inductor in parallel across the gate terminal d) connecting an inductor in series with the gate
Answer: b Explanation: Applying the higher gate current spreads the ions quickly and avoids hotspot formation.
Answer: b
Explanation: Applying the higher gate current spreads the ions quickly and avoids
hotspot formation.
See less173. The dv/dt protection is provided in order to a) limit the power loss b) reduce the junction temperature c) avoid accidental turn-on of the device d) avoiding sudden large voltage across the load
Answer: c Explanation: Accidentally some voltage spike or noise may occur in the vicinity of the device, if the magnitude is large enough it may turn on the SCR.
Answer: c
Explanation: Accidentally some voltage spike or noise may occur in the vicinity of the
device, if the magnitude is large enough it may turn on the SCR.
See less174. dv/dt protection is provided to the SCR by a) connecting a capacitor in parallel with the load b) connecting an inductor in series with the load c) connecting a capacitor & resister in parallel with the device d) connecting an inductor & resister in parallel with the device
Answer: c Explanation: Snubber circuit R-C in parallel with SCR is connected for dv/dt protection.
Answer: c
Explanation: Snubber circuit R-C in parallel with SCR is connected for dv/dt protection.
See less176. The effect of over-voltages on SCR are minimized by using a) RL circuits b) Circuit breakers c) Varistors d) di/dt inductor
Answer: c Explanation: Varistors are non-linear voltage clamping devices, RC circuits across the loads can also be used.
Answer: c
Explanation: Varistors are non-linear voltage clamping devices, RC circuits across the
loads can also be used.
See less177. Over-current protection in SCRs is achieved through the use of a) Varistors b) Snubber Circuits c) F.A.C.L.F & C.B. d) Zener diodes
Answer: c Explanation: FACLF stands for Fast Acting Current Limiting Fuse.
Answer: c
Explanation: FACLF stands for Fast Acting Current Limiting Fuse.
See less178. False triggering of the SCRs by varying flux & noise is avoided by using a) F.A.C.L.F & C.B b) Shielded cables & twisted gate leads c) Snubber circuits d) di/dt inductor in series with the gate terminal
Answer: b Explanation: Shielded cables provide isolation from outside noise
Answer: b
Explanation: Shielded cables provide isolation from outside noise
See less180. Thyristors are used in electronic crowbar protection circuits because it possesses a) high surge current capabilities b) high amp 2 -sec rating c) less switching losses d) voltage clamping properties
Answer: a Explanation: Crowbar protection circuits have high surge current capabilities
Answer: a
Explanation: Crowbar protection circuits have high surge current capabilities
See less