A DC Machine is rated for 250 kW, 180 V, with 8 kW of losses and a moment of inertia of 175kgm^2. The motor rated speed is 1250 rpm. a. Find the time to slow to 50% of its rotational speed when coasting to stop.. b. Find the time to slow to 50% of its rotational speed when dynamically braked with Rsh = 0.25 22. c. Find the time to slow to 50% of its rotational speed when plugged with Rplug = 0.5 2.

A DC Machine is rated for 250 kW, 180 V, with 8 kW of losses and a moment of inertia of 175kgm^2. The motor rated speed is 1250 rpm. a. Find the time to slow to 50% of its rotational speed when coasting to stop.. b. Find the time to slow to 50% of its rotational speed when dynamically braked with Rsh = 0.25 22. c. Find the time to slow to 50% of its rotational speed when plugged with Rplug = 0.5 2.

Power System Analysis and Design (MindTap Course List)

6th Edition

ISBN:9781305632134

Author:J. Duncan Glover, Thomas Overbye, Mulukutla S. Sarma

Publisher:J. Duncan Glover, Thomas Overbye, Mulukutla S. Sarma

Chapter11: Transient Stability

Section: Chapter Questions

Problem 11.18P

See similar textbooks

Similar questions

Consider the design of a home-built wind turbine using a 350-W automobile dc generator. The goal is to deliver 70 kWh in a 30-day month. 1- What capacity factor would be needed for the machine? 2- If the average wind speed is 5 m/s, and Rayleigh statistics apply, what should the rotor diameter be? 3- How fast would the wind have to blow to cause the turbine to put out its full 0.35 kW if the machine is 20% efficient at that point? 4- If the tip-speed-ratio is assumed to be 4, what gear ratio would be needed to match the rotor speed to the generator if the generator needs to turn at 1000 rpm to deliver its rated 350 W? 5- If Rayleigh statistics apply, what is the energy generated in a 30-day month when wind blows between its rated wind speed of 13 m/s and its furling wind speed of 25 m/s?
15.1 Consider a wind machine designed to deliver its rated power at the average velocity for a given wind spectrum. It will be marketed for sites having wind velocity spectra that have the same annual average velocity but with Weibull statistics ranging from k = 3/2 to 5/2. a. Calculate the ratio of maximum to minimum annual average on-site wind power available for exploitation for this range of wind fields. b. What additional assumptions are necessary if the power actually produced is to be in the same ratio as in (a) above?
An electric motor draws a current of 10 amperes with a voltage of 110 V. The output shaft develops a torque of 10.2 N-m and a rotational speed of 1000 rpm. For operation at steady state, determine:a. The electric power required by the motor and the power developed by the output shaft, each in kWb. The net power input to the motor, in kWc. The amount of energy transferred to the motor by electrical work and the amount of energy transferred out of the motor by the shaft, in kW-hr during 2 hours of operation.
Find the power involved in a rotational motion associated with a torque of 25 N·m when the rotational speed is 70 rpm (that is, the rotational speed is 70 revolutions per minute). Hint: Look carefully at the units and first convert the rotational speed units to radians/second (rad/s).
A 4-pole, lap-wound dc machine has 738 armature conductors. Its field winding is excited from a dc source to create an air-gap flux of 27 mWb/pole. The machine (generator) is run from a primemover (diesel engine) at 1200 rpm. It supplies a current of 80 A to an electric load. (a) Calculate the electromagnetic power developed. (b) What is the mechanical power that is fed from the primemover to the generator?
A 220V DC motor rotating with a speed of 1500 rpm (revolutions per minute) is connected to a mechanical load. The current of the motor is 10A. If the torque applied to the load is 13Nm, compute the total power loss in the motor. (Note: P=2πTf, where P=Mechanical power, T=Torque and f=frequency in Hz.)
A PM DC motor with torque constant kPM is usedto power a hydraulic pump; the pump is a positivedisplacement type and generates a flow proportional tothe pump velocity: qp = kpω. The fluid travels througha conduit of negligible resistance; an accumulator isincluded to smooth out the pulsations of the pump.A hydraulic load (modeled by a fluid resistance R) isconnected between the pipe and a reservoir (assumedat zero pressure). Sketch the motor-pump circuit.Derive the dynamic equations for the system, anddetermine the transfer function between motor voltageand the pressure across the load.
A 30kW, 150V DC shunt machine has an armature and field resistances of 0.08Ω and 160Ω respectively. Determine the total armature power developed when working as motor taking 30kW input. a) find the total armature power mathmatically
An 8-pole d.c. machine of 1200kW, 600V, 500 rpm and the average value of the reactance voltage per coil is 6.6V. the machine is lap connected of 648 conductor and each coil has two turns, the axial length of the compole 29 cm and the air gap is 0.8 cm, the armature diameter is 0.35m and the ratio (Bmax/Bav) = 1.5. Find the interpole m.m.f.
A dc motor develops 55 N-m of torque at a speed of 600 rad/s when 12 V are applied. It stalls out at this voltage with 100 N-m of torque. If the inertia and damping of the armature are 7 ?? − ?2 and 3 ???/???, respectively, find the transfer function ?(?) = ?? (?)⁄??(?) and space-state representation of this motor if it drives an inertia load of 105 ?? − ?2 through a gear train, as shown in figure 3 a. Use Simulink to represent the space-state of the system and get the response of the motor.
A horizontal conveyor belt moving at a uniform velocity of 1m/s transports load at the rate of 50,000 kg/hour. The belt is 180m long and is driven by a 960 rev/min motor. Determine the equivalent rotational inertia at the motor shaft. Calculate the required braking torque at the motor shaft to stop the belt at a uniform rate in 10 seconds.
A 20-kW 127.4 -V separately excited dc machine is operated at a constant speed of 2702 rpm with a constant field current such that the open-circuit armature voltage is 127.4 V. the armature resistance is 0.03 ohm. Compute the power input to the motor when the terminal voltage is 133. a. 1154440.00 W b. -23781.33 W c. 24826.67 W d. 0 A