Voltage ratio

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Voltage ratio

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Description : Define: 1) voltage ratio, 2) current ratio, 3) transformation ratio of transformer.

Last Answer : 1) Voltage ratio: The voltages in primary and secondary winding is proportional to number of turns in primary and secondary respectively. So, the voltage ratio is same as transformation ratio. V2/V1 = N2 ... as transformation ratio of transformer. It is denoted by K. K = N2/N1

Description : A dc chopper is fed from a constant voltage mains the duty ratio of chopper is progressively increased while the chopper feeds an RL load. The per unit current ripple would  (1) increase progressively  (2 ... 0.5 and then increase  (4) increase to a maximum value at α = 0.5 and then decrease

Last Answer : A dc chopper is fed from a constant voltage mains the duty ratio of chopper is progressively increased while the chopper feeds an RL load. The per unit current ripple would increase to a maximum value at α = 0.5 and then decrease

Last Answer : The mechanical power developed by a shunt motor will be maximum when the ratio of back e.m.f. to applied voltage is 0.5.

Description : The voltage transformation ratio of a transformer is equal to the ratio of?

Last Answer : The voltage transformation ratio of a transformer is equal to the ratio of secondary induced e.m.f. to primary induced e.m.f.

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Description : The ratio of full -load volt-amperes to short-circuit volt-amperes is equal to :

Last Answer : The ratio of full -load volt-amperes to short-circuit volt-amperes is equal to : Z (p.u)

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Last Answer : The ratio of active power to apparent power is known as power factor.

Last Answer : The form factor is the ratio of r.m.s. value to average value.

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Description : What is transformation ratio?

Last Answer : Transformation Ratio (k):- It is the ratio of secondary number of turns to primary number of turns. OR It is the ratio of secondary voltage to primary voltage. OR It is the ratio of primary current to secondary current. 

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Last Answer : C

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Last Answer : The ratio of limiting friction and normal reaction is known as coefficient of friction.

Last Answer : The ratio of starting torque to full-load torque is least in case of shunt motors.

Last Answer : A synchronous machine with low value of short-circuit ratio has lower stability limit.

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Last Answer : Auto-transformer makes effective saving on copper and copper losses, when its transformation ratio is approximately equal to 1.

Description : Use of auto-transformer is economical when the transformation ratio is?

Last Answer : Use of auto-transformer is economical when the transformation ratio is near unity.

Description : Limitation and application of High Voltage DC (HVDC)

Last Answer : Limitation and application of High Voltage DC (HVDC) :  Limitation:- 1) It is difficult to step up and step down DC voltage like AC voltage. 2) Special cooling ... conventional/non-conventional) 12) Increasing existing grid utilization. 13) Interconnection of different grids or networks

Description : State standard voltage in India for the following : (i) Generation Voltage (ii) Primary Transmission Voltage

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Last Answer : Current would kill. You can actually have thousands of bolts going through you and not even know it. Yes you probably know already voltage is current times resistance. Since your body is a resistor it would take just a small amount of current to create a very high voltage

Description : Define: i) Knee voltage ii) Reverse saturation current 

Last Answer : i) Knee voltage : The applied forward voltage, at which the PN junction starts conducting and current starts increasing exponentially is called knee voltage. It is 0.7V for Si and 0. ... semiconductor diode caused by diffusion of minority carriers from the neutral regions to the depletion region.

Description : If 1-phase voltage is 220V, why is 3-phase 440V and not 660V ?

Last Answer : Phase voltage =220v /( phase to neutral) Line voltage = 380 v ( phase to phase) Phase angle difference 120° So when two phases reach vmax +ve I.e. (+220v) + (+220v) = 440v that time due ... these event happen very fast. Hence we have 440 v only in three phase motor. √3.phase voltage= 380 v.

Description : Is the power line voltage available in our homes a dc or an ac voltage?

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Description : Voltage divider rule

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Description : Explain how sinusoidal AC voltage is generated by using simple one loop generator.

Last Answer : An electric current produced by means of electrical machine is known as generator which converts mechanical energy into electrical energy. When conductor cuts the magnetic flux, emf induced in it. (Faraday' ... upon position of armature. The nature of emf is alternating as shown by the waveform. 

Description : Explain lagging quantity and leading quantity, explain this concept with voltage and current waveform

Last Answer : When two alternating quantities attain their respective zero or peak values simultaneously, the quantities are said to be in-phase quantities. When the quantities do not attain their respective zero or ... current is leading the voltage or the voltage is said to be lagging behind the current.

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Description : Define pinch off voltage and drain resistance of FET.

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Description : Define Depletion region and Barrier voltage of PN junction.

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Description : State the concept of internal voltage drop.

Last Answer : Concept of internal voltage drop: Every practical source offers some opposition to the current due to its internal parts or components. e.g. a 12V battery has electrodes made up of conducting ... internal voltage drop, the terminal voltage of practical voltage source is always less than its emf. 

Description : Define : (i) Dielectric strength (ii) Breakdown voltage

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Description : What is internal voltage drop and terminal voltage?

Last Answer : It is not permissible to just connect the positive terminal to the negative terminal of a cell with a copper wire. It will overheat and get damaged. This happens because the electromotive force (emf) ... than the nominal voltage (emf) of the cell and this lower voltage is called terminal voltage.

Description :  An independent voltage source in series with an impedance ZS=R+jXS delivers a maximum average power to a load impedance ZL when A) ZL = R B) ZL = jXS C) ZL = R-jXS D) ZL = R+jXS 

Last Answer :  An independent voltage source in series with an impedance ZS=R+jXS delivers a maximum average power to a load impedance ZL when ZL = R-jXS

Description : Which of the following connection of transformers will give highest value of secondary voltage ? (A) Delta primary delta secondary (B) Delta primary star secondary (C) Star primary star secondary (D) Star primary delta secondary

Last Answer : Which of the following connection of transformers will give highest value of secondary voltage ? (A) Delta primary delta secondary (B) Delta primary star secondary (C) Star primary star secondary (D) Star primary delta secondary