Recent questions tagged single-phase

by anonymous asked Oct 13, 2019 119 views

Single-phase mid-point controlled rectifier with RL load
Answer : Single-phase mid-point controlled rectifier with RL load : The circuit configuration of single-phase midpoint controlled rectifier is shown in the figure. During positive half-cycle of ... some part of next positive half-cycle of voltage with reversed polarity can appear across load. ...

by anonymous asked Oct 13, 2019 295 views

Single-phase Midpoint controlled rectifier with Resistive load
Answer : Single-phase Midpoint controlled rectifier with Resistive load:  1) During positive half cycle of AC supply, a is positive with respect to b , this makes T1 forward biased and T2 is reverse ... voltage reverses the polarity and T2 is turned off. The operation is as shown in waveforms. ...

by anonymous asked Apr 29, 2018 374 views

When the firing angle a of a single-phase, fully controlled rectifier feeding constant direct current into a load is 30°, the displacement power factor of the rectifier is
Answer : When the firing angle a of a single-phase, fully controlled rectifier feeding constant direct current into a load is 30°, the displacement power factor of the rectifier is √3/2 ...

by anonymous asked Apr 29, 2018 101 views

An additional condition for parallel operation of three-phase transformers over single-phase transformers is that
Answer : An additional condition for parallel operation of three-phase transformers over single-phase transformers is that the transformers should belong to the same vector group ...

by anonymous asked Apr 29, 2018 85 views

In a single-phase induction motor, the operating direction is determined by the ________ A) Rotor B) Stator C) Starting circuit D) None of these
Answer : In a single-phase induction motor, the operating direction is determined by the Starting circuit ...

by anonymous asked Apr 28, 2018 133 views

The no-load speed of a single-phase SCR bridge converter fed separately excited dc motor operating at a firing delay angle, α and flux, Φ (A) directly proportional to α and Φ (B) ... proportional to α and inversely proportional to Φ (D) directly proportional to Φ and inversely proportional to α
Answer : The no-load speed of a single-phase SCR bridge converter fed separately excited dc motor operating at a firing delay angle, α and flux, Φ directly proportional to α and inversely proportional to Φ ...

by anonymous asked Apr 28, 2018 130 views

A 230 V, 50 Hz phase controlled single-phase full-controlled SCR bridge converter draws 15 A constant dc current. If the source inductance is 3 mH, the drop in dc output voltage is (A) 4.5 V (B) 6.75 V (C) 9 V (D) 13.5 V
Answer : A 230 V, 50 Hz phase controlled single-phase full-controlled SCR bridge converter draws 15 A constant dc current. If the source inductance is 3 mH, the drop in dc output voltage is 9 V ...

by anonymous asked Apr 28, 2018 136 views

In a 230 V, 50 Hz single-phase SCR bridge converter operating at a firing delay angle, α and with large R-L load, the input source current is (A) sinusoidal current (B) constant dc current (C) continuous rectangular pulses (D) alternating rectangular pulses
Answer : In a 230 V, 50 Hz single-phase SCR bridge converter operating at a firing delay angle, α and with large R-L load, the input source current is alternating rectangular pulses ...

by anonymous asked Apr 28, 2018 408 views

The sequence components of current of a single-phase load connected to a 3-phase system are (A) equal positive and negative sequence components (B) equal positive, negative and zero sequence components (C) vector sum of sequence currents is zero (D) algebraic sum of sequence currents is zero
Answer : The sequence components of current of a single-phase load connected to a 3-phase system are equal positive, negative and zero sequence components ...

by anonymous asked Apr 28, 2018 82 views

In a single-phase induction motor when the rotor is stationary and voltage is applied to the stator, then (A) the flux is constant (B) the flux first decreases and then increases in ... increases and decreases in the opposite direction with the same magnitude (D) current flows through the rotor
Answer : In a single-phase induction motor when the rotor is stationary and voltage is applied to the stator, then the flux first decreases and then increases in the same direction ...

by anonymous asked Apr 28, 2018 96 views

A 230 V/460 V single-phase transformer operating at 20 A and unity power factor has primary referred resistance of 0.2 Ω and reactance of 0.5 Ω. The approximate primary induced emf is (A) 216 V (B) 226 V (C) 234 V (D) 236 V
Answer : A 230 V/460 V single-phase transformer operating at 20 A and unity power factor has primary referred resistance of 0.2 Ω and reactance of 0.5 Ω. The approximate primary induced emf is 226 V ...

by anonymous asked Apr 28, 2018 73 views

In a single-phase transformer, the magnetizing current is (A) in phase with the no-load current (B) in quadrature with the no-load current (C) the product of no-load current and power factor (D) in phase with the flux in the core
Answer : In a single-phase transformer, the magnetizing current is in phase with the flux in the core ...

by anonymous asked Mar 20, 2018 82 views

Answer : The starting winding of a single-phase motor is placed in stator. ...

by anonymous asked Mar 20, 2018 117 views

Answer : The capacitors used in single-phase capacitor motors have no polarity marking. ...

by anonymous asked Mar 20, 2018 212 views

Answer : If starting winding of a single-phase induction motor is left in the circuit, it will draw excessive current and overheat. ...

by anonymous asked Mar 20, 2018 61 views

Answer : A single-phase induction motor is inherently non-self-starting with low torque. ...

by anonymous asked Mar 20, 2018 134 views

Answer : The power factor of a single-phase induction motor is usually lagging. ...

by anonymous asked Mar 20, 2018 122 views

Answer : In a capacitor start single-phase motor, when capacitor is replaced by a resistance motor will continue to run in same direction. ...

by anonymous asked Mar 20, 2018 105 views

Answer : In a shaded pole single-phase motor, the revolving field is produced by the use of shading coils. ...

by anonymous asked Mar 20, 2018 69 views

Answer : The rotor developed by a single-phase motor at starting is zero. ...