Calculate motor efficiency, Electrical Engineering

1. A self excited shunt generator supplies a load of 12.5 kw at 125 volts. The field resistance is 25 ohms and the armature resistance is 0.2 ohms. The total voltage drop because of brush current and armature reaction at this load is 3 volts. Calculate the induced armature voltage.

2. A 6 pole lap-wound armature having 720 conductors, rotates in a field of 20.35 mWb. (a) If the induced current is 72 A, what is the torque developed by armature? (b) If the induced armature voltage is 410V, what is the motor speed?

3. A shunt motor runs at 1100 rpm at 230v and draws a line current of 40 A. The output power(at the shaft) is 10.8 h.p. The various losses are core loss, 200W: friction and windage loss 140W: electrical loss due to brush contact, 32W: stray load loss, 31W. The armature and field-current resistance are 0.2 ohms and 220 ohms respectively. Calculate (a) motor efficiency, (b) the speed if the output power is reduced by 50%.

4. A 4 pole motor is lap wound with 728 conductors and has a flux of 25 mWb per pole. The armature takes 50 A in current: the resultant demagnetizing effect due to armature reaction reduces the air gap flux by 5%. Calculate the developed torque.

5. One of three fuses protecting a 3-phase electric heater rated at 200kW, 600 V is removed so as to reduce the heat produced by the boiler. What power does the heater develop under these conditions?

 

Posted Date: 2/25/2013 1:06:11 AM | Location : United States







Related Discussions:- Calculate motor efficiency, Assignment Help, Ask Question on Calculate motor efficiency, Get Answer, Expert's Help, Calculate motor efficiency Discussions

Write discussion on Calculate motor efficiency
Your posts are moderated
Related Questions
Q. Obtain the truth table for the logic block shown in Figure

Off line UPS System Again the two  switches  are used in this  type of ups  as online  ups. The difference  is that  here  the main  static  switch  remains normally  ON and UP

Q. Illustrate working of Direct-coupled Amplifiers? Direct-coupled Amplifiers : The following figure shows a direct-coupled amplifier consisting of two stages. A dc voltage i

R.h. corkscrew rule Note the direction of the flux is given by Maxwell's 'R.H. corkscrew rule' and that the flux lines are continuous Applying  Ampere's  Law  to  a  concentri

Q. Amplifiers with Feedback? Almost all practical amplifier circuits include some form of negative feedback. The advantages gained with feedback may include the following: •

Q. When input is a triangular wave. When the input fed to differentiating circuit is a triangular wave, the output will be a rectangular wave. During the period OA of

what is inductor

Consider an RLC series circuit excited by v(t) = V m cos ωt in the time domain. By using superposition, solve for the time-domain forced response of the resultant current through

When both MT 2 and Gate  are Negative In this case N 3   works as a remote gate. Current  flows form layer P 2 to layer  N 3 junction N 1 P 1 is reverse biased  and it  br

Q. Explain topology method used in LAN technology? Ans: LAN Topologies: Network topology is a physical schematic which demonstrates interconnection of the many users. Th