Bissoy.com
Doctors Medicines MCQs Q&A

A single phase motor is connected to 400V, 50Hz supply. The motor draws a current of 31.7A at a power factor 0.7 lag. The additional reactive power (in VAR) to be supplied by the capacitor bank will be ___________

A single phase motor is connected to 400V, 50Hz supply. The motor draws a current of 31.7A at a power factor 0.7 lag. The additional reactive power (in VAR) to be supplied by the capacitor bank will be ___________ Correct Answer 4756

Active power drawn by the motor=VIcosФ = 400*31.7*0.7 = 8876 W Reactive power = VIsinФ=400*31.7*sin(45.57.29) = 9055.3 VAR New power factor=cosθ2 = 0.9 θ2=cos-1(0.9) Q2=8876*tan(25.84) = 4298.855 VAR Change in reactive power=9055.3-4298.855 = 4756.4 VAR.

Related Questions

A single phase motor is connected to 400V, 50Hz supply. The motor draws a current of 31.7A at a power factor 0.7 lag. The capacitance required in parallel with motor to raise the power factor of 0.9 lag (in micro farads) is ___________
A single phase motor is connected to 400V, 50Hz supply. The motor draws a current of 31.7A at a power factor 0.7 lag. The capacitance required in parallel with motor to raise the power factor of 0.9 lag (in micro farads) is __________
Given that 100.48=x, 100.70=yandxz=y2, then the value ofzis close to ___ ?
The network formed by resistors and capacitors for modifying the rate of change of gain and the phase shift is called a compensating network. Which of the following statements are not correct ? (A) The main purpose of a compensating network is to modify the performance of op-amp ciruit over the desired frequency range (B) There are two types of op-amps : internally compensated and externally compensated (C) 741 C is an externally compensated op-amp while 709 C is internally compensated op-amp (D) The phase lag and phase lead are most commonly used compensating networks in op-amps (E) Phase lag contributes a positive phase angle and phase lead a negative phase angle Choose the most appropriate answer from the options given below : 
Consider a system consisting of a synchronous generator working at a lagging power factor, a synchronous motor working at an overexcited condition and a directly grid-connected induction generator. Consider capacitive VAr to be a source and inductive VAr to be a sink of reactive power. Which one of the following statements is TRUE?
In a web server, ten WebPages are stored with URLs of the form http://www.yourname.com/var.html; where; var is a different number from 1 to 10 for each Webpage. Suppose, the client stores the Webpage with var = 1 (say W1) in local machine, edits and then tests. Rest of the WebPages remains on the web server. W1 contains several relative URLs of the form ‘’var.html’’ referring to the other WebPages. Which one of the following statements needs to be added in W1, so that all the relative URLs in W1 refer to the appropriate WebPages on the web server?
What is the value of var? $var = 'HELLO WORLD!'; $var = ucfirst($var);
If A = x% of y and B = y% of x, then which of the following is true?
When an electric current coil of a wattmeter is connected to the electric current path R and the voltage coil is connected between the electric current R path and the neutral side of the balanced three phase supply, it shows 10 kW. The line voltage along the phase sequence RYB is 400 V. The current drawn by the current path is 54 A. What is the new reading of the wattmeter if the voltage coil is connected between the lines B and the Y paths, even if the electric current coil is continuously present in the line R?
Discrete transistors T1 and T2 having maximum collector current rating of 0.75A are connected in parallel as shown in the figure. This combination is treated as a single transistor to carry a single current of 1A, when biased with a self bias circuit. When the circuit is switched ON, T1 had draws 0.55A and T2 draws 0.45A. If the supply is kept ON continuously, it is very likely that_________