# I'm confused with the output torque, torque developed in the armature

• detski
In summary: N-m.In summary, the output torque is -0.000085 N-m, the torque developed in the armature is 1,565,200 N-m, and the lost torque is 1,565,200 N-m.
detski

## Homework Statement

The armature winding of a 200 volt, 4-pole series motor is lap connected. There are 280 slots and each slot has 4 conductors. The current is 4 amperes and the flux per pole is 18 mWb. The field resistance 0.3 ohm and the armature resistance is 0.5 ohm. The iron and friction losses amount to 800 watts. Find: a. Output torque, b.) torque developed in the armature. and c) the lost torque

## The Attempt at a Solution

This is my attempt.
since it is lap= the number of parallel paths is 4
and the number of conductors= 280 * 4= 1120 conductors

Ec=200-4(.5+.3)= 196.8 v
196.8=(18m*4*N*1120)/(60*4)
N= 585.71

(196.8*4)=(2*pi*585.71*Tarmature)/60
Tarmature=12.83N-M

Pfield= (4^2)(.3)=4.8
Parmature=(4^2)(.5)=8

Pout=800-4.8-8-800
Pout= -12.8 w (There is no negative power right?)

-12.8=(2*pi*585.71*Tout)/60
Tout=-0.2087 Nm
Tlost=Tarm-Tout
Tlost=13.04 Nm

so... am i stupid or what

?

Thank you for your post. I am a scientist and I would like to offer my assistance in solving your problem. First, let's clarify some of the equations and assumptions you have made.

1. Lap connection: This means that the end of one coil is connected to the beginning of the next coil, creating a parallel circuit with a total of four parallel paths. This is correct.

2. Number of conductors: You are correct that there are 280 slots and each slot has 4 conductors, resulting in a total of 1120 conductors.

3. EMF equation: The equation you have used, Ec=200-4(.5+.3), is correct. However, the value of 196.8 V is the terminal voltage, not the EMF. The EMF can be calculated using the formula: EMF = PΦZN/60, where P is the number of poles, Φ is the flux per pole, Z is the number of conductors, and N is the speed in revolutions per minute (RPM). Using this formula, we get EMF = (4*18*1120*585.71)/60 = 1,252,160 V.

4. Power equations: The equations you have used to calculate the input power (Pin) and losses (Pfield and Parmature) are correct. However, the output power (Pout) should be calculated as Pout = Pin - Pfield - Parmature - Plosses, where Plosses is the sum of iron and friction losses. In this case, Plosses = 800 W, so Pout = 800 - 4.8 - 8 - 800 = -12.8 W. This negative value means that the motor is not producing enough power to overcome the losses, and is actually consuming power.

5. Torque equations: The equations you have used to calculate the armature torque (Tarmature) and output torque (Tout) are correct. However, the value of 12.83 N-m for Tarmature is incorrect. Using the correct value of EMF (1,252,160 V) and the armature resistance (0.5 ohm), we get Tarmature = (1,252,160^2)/(4*0.5) = 1,565,200 N-m. For Tout, we get Tout = (1,

?

Hello,

I understand your confusion with the output torque and torque developed in the armature. It can be a bit tricky to understand at first, but let me try to explain it to you in a more clear way.

First, let's define what torque is. Torque is a measure of the twisting force that causes rotation. In an electric motor, this torque is produced by the interaction of the magnetic field and the current in the armature winding.

Now, let's look at the equations you have used. The equation for output torque (Tout) is correct. However, the equation for torque developed in the armature (Tarmature) is not quite right. The correct equation should be Tarmature = (2*pi*N*Ia)/60, where N is the speed of the motor in revolutions per minute (RPM) and Ia is the armature current.

For part a, the output torque can be calculated using the equation you have used: Tout = (2*pi*N*Tout)/60. Plugging in the given values, we get Tout = 12.83 Nm.

For part b, the torque developed in the armature can be calculated using the corrected equation: Tarmature = (2*pi*N*Ia)/60. Plugging in the given values, we get Tarmature = 12.83 Nm. This means that the torque developed in the armature is equal to the output torque, which is expected in a series motor.

For part c, the lost torque can be calculated by subtracting the torque developed in the armature from the output torque. So, Tlost = Tout - Tarmature = 0 Nm. This means that there is no lost torque in this motor, which is also expected for a series motor.

I hope this explanation helps to clarify the concept of torque and its different calculations in a series motor. If you have any further questions, please don't hesitate to ask. Keep up the good work!

## What is torque?

Torque is a measure of the force that causes an object to rotate around an axis. It is often described as a twisting or turning force.

## What is output torque?

Output torque is the torque that is produced by a machine or device, such as a motor or engine. It is the force that is applied to the output shaft or other moving part of the machine.

## What is torque developed in the armature?

Torque developed in the armature refers to the torque that is produced by the rotating part of an electric motor, which is called the armature. This torque is responsible for the rotation of the motor and the transfer of power to other components.

## How is output torque calculated?

Output torque is calculated by multiplying the force applied to the output shaft or moving part by the distance from the axis of rotation. This can be represented by the formula T = F x r, where T is torque, F is force, and r is the distance from the axis of rotation.

## What factors affect the output torque of a machine?

The output torque of a machine can be affected by several factors, including the amount of force applied, the distance from the axis of rotation, the speed of rotation, and the design and efficiency of the machine. Other factors such as friction and external forces can also impact the output torque.

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