A motor operating on 230 V electricity has a 188 V back emf at operating speed...
A 120-V, series-wound motor has a field resistance of 4.0 and an armature resistance of 2.5 . (a) Determine the current drawn by the motor at the very instant it is switched on, i.e., when it has not started to rotate. (b) When it is operating at nominal speed, a back emf of 85.0 V is generated. How much current is drawn in this case? (c) What is the furnished mechanical power? (d) How much power is dissipated?...
Suppose a motor connected to a 135 V source draws 21.5 A when it first starts. (a) What is its resistance (in Ω)? Answer in Ω. (b) What current (in A) does it draw at its normal operating speed when it develops a 100 V back emf? Answer in A. (c) What is the voltage output (in V) of a transformer used for rechargeable flashlight batteries, if its primary has 525 turns, its secondary 8 turns, and the input voltage...
A 120 V electric motor is running with a current of 3 A. When initially started the motor draws 16 A. What is the back emf of the motor at normal operating speed?
5. A motor has coils with a resistance of 30.0 and operates from a voltage of 240 V. When the motor is operating at its maximum speed, the back emf is 145 V. Find the current in the coils (a) when the motor is first turned on and (b) when the motor has reached maximum speed. (c) If the current in the motor is 6.0 A at some instant, what is the back emf at that time?
A motor has calls with a resistance of 25 ohm and operates from a voltage of 238 V. When the motor is operating at its maximum speed, the back emf is 149 V. Find the current in the calls when the motor is first turned on. A Find the current in the calls when the motor has reached maximum speed. A If the current in the motor were 7.0 A at some instant, what the back emf at that time?...
Problem 6: A 230-V shunt motor has an armature resistance of 0.05 Ohms and a field resistance of 75 Ohms. The motor draws 7 A of line current while running light at 1120 rpm. The line current at a certain load is 46 A. (a) What is the motor speed at this load? (b) At this load, if the field circuit resistance is increased to 100 Ohms, what is the new speed of the motor? Assume linearity between the flux...
3. A 25-kW, 230-V shunt motor has an armature resistance of 0.064 Ω and a field-circuit resistance of 95 Ω. The motor delivers rated output power at rated voltage when its armature current is 122 A. When the motor is operating at rated voltage, the speed is observed to be 1150 r/min when the machine is loaded such that the armature current is 69.5 A a. Calculate the rated-load speed of this motor In order to protect both the motor...
A 230 V, 1000 rpm, 30 A separately excited motor has armature resistance and inductance of 0.7 Ω and 50 mH respectively. Motor is controlled in regenerative braking by a chopper operating at 800 Hz from a dc source of 230 V. Assuming continuous conduction a) Calculate duty ratio of chopper for rated torque and the speed of 800 rpm. b) What will be the motor speed for duty ratio of 0.6 and rated motor torque? c) What will be...
5.7. A DC machine has a back-emf constant of 0.24 V/(rad/s) and a resistance of 0.5 ohms. It is operating from a 12V DC power supply. At its rated speed of 400 rpm, calculate its (a) rated back-emf voltage (that is, the back-emf at rated speed) (b)rated current (that is, the current at rated speed) (c) rated torque (d) rated output power POUT= To (e) rated output power POUT = EI (f) rated input power (g) rated efficiency-PouTlPi (h) rated...
1. A motor has an armature resistance of 3.00 Q. If it draws 5.00 A when running at full speed and connected to a 125 V line, how large is the back emf? Volts