grp report

7/31/2019 Grp Report

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1.0 HEALTH AND SAFETY WARNINGS AND PRECAUTIONS

1.1 Safety

Before proceeding to install commission or operate this equipment you are directed

to read the following safety notes. The notes are intended to help you to be aware of

potential hazards and thereby avoid accidents. Particular note should be taken to

ensure that the positioning of the unit is on a suitably firm table, in a position where

it will not fall to ground due to unbalance placing or provide a risk which will drop on

the foot of people passing by. Care should be taken not to expose the wires to the

external environment to prevent any electrical leakage or short circuit which might

cause injuries to the people who are nearby to the machine. Where appropriate,

further information and recommendations are incorporated in the main body of this

manual. In all cases the requirements of relevant local health and safety regulations

should be complied with.

1.2 Electrical Equipment

This equipment operates from a 12V dc supply voltage, which dry cells or 12V

batteries are recommended as the voltage source. Electrical installation and

maintenance therefore must be carried out within certain period of time with local

regulations to ensure the equipments condition.

a) Installation

The electrical supply of voltage and configuration must be ensured to be compatible

with this equipment which requires a 12V DC supply and one set of connecting wires

with metal clips.

The electrical supply and connecting cable should be suitably rated with respect to

current, temperature and physical protection for the conditions of use. The supply

outlet should be suitably labeled and must incorporate an independent means of

isolating the supply and be fitted with a suitable over-current protection device.


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b) Maintenance

The batteries should be ensured that its not connected to the equipment when the

equipment is not in use.

The equipment should be isolated from the electrical supply before removing the DC

motor from the motor stand to expose any part that in operation which carries a 12V

DC current which may cause electrical shock injuries.

The conditions of connecting wire which connects voltmeter and ammeter should be

inspected periodically to ensure the safety of this machine.


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2.0 GENERAL DESCRIPTION OF DC MOTOR TESTER

2.1 Machine Description

Figure 1: Main components of the DC motor tester.

The DC Motor Tester comprises:

i. A main stand.ii. Voltmeter and ammeter which contained within the control box.iii. Rotation controller.iv. Timer.v. DC motor connecting switch.vi. Adjustable DC motor stand.vii. Rotating Disc.viii. Color sensor.ix. O-ring (refer to appendix).x. 2 sets of connecting wires.xi. Belt (refer to appendix).

The DC motor tester requires a 12V DC voltage supply.

In any correspondence with the manufacturer concerning this machine, please quote

the full serial number of the machine and sent to our office.


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The DC motor is to be placed at the adjustable DC motor stand tightened its position

by belt, connecting wires are set to connect the DC motors and iron casting s

terminal. 12V battery is connected to DC motors terminal by connecting wires while

the o-ring is set to connect the shaft of the DC motor and rotating disc. Thus, the dc

current will drive the DC motor shaft to rotate in the same time causes the rotating

disc which connected to the shaft by ring to rotate as well. The rotation controller is

used to control the amount of desired rpm for the rotating disc, once the number of

desired rpm is reached, it will automatically stop the timer to show the required time

for the respective DC motor to reach certain amount of rpm.

2.2 Operation

When the DC motor starts to operate which drives the rotating disc to rotates, the

color sensor will detects the amount of times the black thread which located at the

side of rotating disc passes through the sensor. There is a black thread which locates

at the side surface of rotating disc which emits its own light wave. Thus, when the

rotating disc rotates one full rotation the color sensor will be able to sense the light

wave emits by the black thread and the sensor will collect and determine the number

of signals sent back to ensure tally with the number of set by rotation controller.

When the number of rotations reached, the rotation controller will cut off the

electrical supply to stops the timer and the DC motor. The total time required will

display at the screen of timer.

IMPORTANT

NOTE : IT IS IMPERATIVE THAT WHEN USING THE DC MOTOR TESTER, THEREWILL BE A SLIGHT FRICTION OCCUR BETWEEN THE SURFACE OF THE

DRIVE BELT AND ROTATING DISC AS WELL AS THE DC MOTORS SHAFT.

THE EFFECT OF FRICTION CAN BE MINIMIZED BY APPLY LUBRICANT OIL

ON THE SIDE SURFACE OF THE ROTATING SIDE AND DC MOTORS SHAFT

BEFORE DRIVE BELT IS INSTALLED.


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3.0 INSTALLATION

1) Remove all the packing materials carefully from its package cover.2) Position the main stand on the table.3) Place the rotating disc on the correct position on the main stand such a way

the centre hole of the rotating disc is in the same position with the hole on

the main stand.

4) Place the color sensor on the aluminum bar on the same height with rotatingdiscs side surface such a way that the black thread is the same height as the

color sensor.

5) Insert the aluminum bar in the hole of the rotating disc and positioned it intothe main stand by tightened it using the nuts provided.

6) Set up motor stand by place it just beside the hole on the main stand beforetightened it with nuts.

7) Connect the voltmeter and ammeter with connecting wires to the main switch.8) Ensure the DC voltage supply is 12V before install into the control box and

connect to the main switch of the control box.

Top View of DC Motor Tester (Labeled)

Figure 2: Top view of DC motor tester.


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Side View of DC Motor Tester (Labeled)

Figure 3: Side view of DC motor tester.

Front View of DC Motor Tester (Labeled)

Figure 4: Front view of DC motor tester.


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4.0 USE OF DC MOTOR TESTER

4.1 Introduction

Figure 5: Simplified diagram of DC motor tester.

Fig. 5 shows the simplified diagram of the DC motor tester which driven by 12V dc

voltage supply. The performances of a DC motor can be judged based on three main

criteria which are the rotation-per-minute (rpm) of the motor, the output torque of

the motor and the efficiency of the motor. When the DC motor rotates at a certain

angular speed, m , it drives the belt which pushes the rotating disc to rotates at its

own angular velocity, r. Thus, if the radius of the motors shaft is known as the

radius of the rotating disc is known, one can derived the formula to determine the

rpm of the DC motor based on the information given above and proper applied

mechanics theories.

When the motors shaft is being driven by the DC supply, the output produced by the

shaft will create a torque which determines the maximum power provided by the

motors shaft. When the rotating disc is rotating about a fixed axis passing through


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the center of it, the body has both translational and rotational kinetic energy. If the

radius of the rotating disc and circular load is the same and known, the energy

equation of the DC motors shaft can be derived by summing up the trans lational

kinetic energy and rotational kinetic energy of both the rotating disc and circular load.

Since the angular velocity of the motors shaft can be determined, one needs to find

out the moment of inertia of both the circular load and rotating disc before the

energy equation of the DC motor can be applied into this situation where the output

energy of the DC motor is to be found.

The main challenge which faced by the world currently in all mechanics field is to

maximize the efficiency of the machine in order to reduce the waste of energy usage

to the minimum. The energy is lost during the work is done which change its form

from mechanical energy into sound energy, heat energy and friction. Thus, the

efficiency of the motor can be determined, given the input power of the supply is

known and the energy consumption of the motor is known. In order to validate the

energy equation, the input supply is assume to have negligible lost of energy during

the transmission. When the rotating disc is rotating about a fixed axis passes

through the center of the disc, it experiences both translational and rotational kinetic

energy. Thus, sum up the amount of energy used by the rotating disc, the equation

of output power is energy divided by time. Therefore, the output power of the motor

can be determined if the amount of time taken is known. The efficiency of the motor

can thus be determined by finding out the ratio of output power and input power.

The Mulan DC motor tester has been designed so that the methods in the

experimental procedure follow those used in theoretical solution. Thus, by using the

machine to determine the rpm of the DC motor under a known system of physical

information of load and motor, the properties of DC motor can be determined by

applying the information into the equation provided.


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5.0 DC MOTOR TESTING EXPERIMENTS

5.1 RPM of Hobby-type DC Motor

5.1.1 Apparatus

DC motor tester, DC motor.

5.1.2 Objective

To determine the RPM (revolutions per minute) of Hobby-type DC Motor.

5.1.3 Theory

Let r = angular velocity of rotating disk, m = angular velocity of DC Motor,

rr = radius of rotating disk, rm = radius of DC Motor,

= number of revolutions in radian

Angular velocity of rotating disk, r =

(A)

In equation v= r,

Since the velocity of rotating disk and DC Motor are the same,

rrr = rmm

Hence, angular Velocity or RPM is inversely proportional to radius of circular.

=

m = r x

(B)

Therefore, RPM of DC Motor = m x

(C)


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5.1.4 Method

First measure the radius of rotating disk of the DC motor tester and the radius of the

DC motor shaft and record as rr and rm respectively.

Place the DC motor on the adjustable motor stand and tighten its position by belt.

Connect the DC motor shaft to the rotating disk using the O-ring so that the motion

of the DC motor can be transferred to the rotating disk. Then, adjust the position of

the DC motor such that the DC motor shaft is in the same horizontal level as the

rotating disk. Also, regulate the tension of the belt by moving the position of the DC

motor forward or backward if necessary.

Adjust the rotation controller to 20 revolutions. This is to ensure that the color

sensor can detect the first 20 revolutions of the rotating disk.

Switch on the DC motor tester and observe the revolutions of the rotating disk. The

timer will start record the time from the first revolution and stop automatically once

the color sensor had detected that the rotating disk had made 20 revolutions. Read

the value on the timer and record the time as t. The number of revolutions is

recorded as in radian. Repeat this experiment for another 2 times.

5.1.5 Results

rr = _____ mm rm = _____ mm

Number of revolutions, (rad.) Time taken forrevolutions, t(s)

20 x 2 = 40

20 x 2 = 40 20 x 2 = 40

Average:

Calculate the average value oftfor use in calculations.


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5.1.6 Calculations

The angular velocity of rotating disk can be calculated using equation (A) quoted in

theory. Then the angular velocity of DC motor can be found by equation (B). The

RPM of DC motor can be determined using equation (C).

5.2 Maximum Energy Provided by Hobby-type DC Motor

5.2.1 Apparatus

DC motor tester, DC motor, circular loads.

5.2.2 Objective

To determine the maximum energy produced by the Hobby-type DC Motor.

5.2.3 Theory

Let m = mass of rotating disk, M = total mass of circular loads

Id = moment of inertia of rotating disk, IL = moment of inertia of circular load

r= radius of rotating disk = radius of circular loads

(The radius of rotating disk and circular load is same)

When the rotating disc is rotating about a fixed axis passing through the center of it,

the body has both translational and rotational kinetic energy. The angular velocity of

both the rotating disk and circular loads are same.

Energy = Rotational kinetic energy of rotating disk + Rotational kinetic energy of

circular load

=

Id+

IL

2

=

(

mr2) 2+

(

Mr2) 2 ,(I=

mr

2)

=

mr22+

Mr22


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=

mr22 +

Mr22 (D)

5.2.4 Method

First measure the radius and mass of rotating disk of the DC motor tester. Record

the values as rand mrespectively.




the DC motor such that the DC motor shaft is in the same horizontal level as therotating disk. Also, regulate the tension of the belt by moving the position of the DC


Place a circular load on the rotating disk. After that, switch on the DC motor tester

and observe the motion of the rotating disk (assume no sliding occurs between

circular loads and rotating disk). Repeat this step until the rotating disk with circular

loads rotate with its minimum speed as if it is not rotating. Record the total mass of

the circular loads as M.



Switch on the DC motor tester and observe the revolutions of the rotating disk. The

timer will start record the time from the first revolution and stop automatically once

the color sensor had detected that the rotating disk had made 20 revolutions. Read

the value on the timer and record the time as t. The number of revolutions is

recorded as in radian. Repeat this experiment for another 2 times.


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5.2.5 Results

r= _____ mm m= _____ kg

Number of revolutions,

(rad.)

Total mass of circular

loads, M(kg)

Time taken for

revolutions, t(s)

20 x 2 = 40

20 x 2 = 40

20 x 2 = 40

Average: Average:

Calculate the average values ofM

andt

for use in calculation.

5.2.6 Calculations

The angular velocity of both the rotating disk and circular load can be found by

equation (A) in experiment 1. Then calculate the maximum energy provided by the

DC motor using equation (D) quoted in the theory.

5.3 Efficiency of Hobby-type DC Motor

5.3.1 Apparatus

DC motor tester, DC motor.

5.3.2 Objective

To determine the efficiency of Hobby-type DC Motor.

5.3.3 Theory

Let V= input voltage, I= input current


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Input Power, P = VI (E)

Output Power

When the rotating disc is rotating about a fixed axis passing through the center of it,

the body has both translational and rotational kinetic energy.

Energy = Rotational kinetic energy of rotating disk

=

I 2

=

(

mr

2) 2(I=

mr

2)

=

mr

2

2 (F)

Hence, Output power =

=

mr

2

2 (G)

Efficiency =

x 100 =

=

% (H)

5.3.4 Method

First measure the radius and mass of rotating disk of the DC motor tester. Record

the values as rand mrespectively.




the DC motor such that the DC motor shaft is in the same horizontal level as the

rotating disk. Also, regulate the tension of the belt by moving the position of the DC





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Switch on the DC motor tester and observe the reading on the voltmeter and

ammeter. Once the reading on the voltmeter and ammeter had reached a stable

value, record the value of voltage and current as Vand Irespectively.

Record the reading on the timer as tonce the rotating disk had made 20 revolutions.

The number of revolutions is recorded as in radian. Repeat this experiment for

another 2 times.

5.3.5 Results

r= _____ mm m= _____ kg

Calculate the average values ofV, I,and tfor use in calculation.

5.3.6 Calculations

The value of input power should be calculated using equation (E). As for the output

power, equation (F) can be used to calculate the output energy while equation (G) is

used to determine the output energy. Next, the efficiency of the DC motor can be

determined using equation (H).

Number of

revolutions,

(rad.)

Input voltage, V

(V)

Input current, I

(A)

Time taken for

revolutions, t(s)

20 x 2 = 40

20 x 2 = 40

20 x 2 = 40

Average: Average: Average:


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6.0 APPENDIX

This is the O-Ring which is used to connect the DC motor shaft and the rotating disk

so that the motion of the DC motor shaft can be transferred to the rotating disk.

This is the belt that is used to tighten the position of the DC motor on the adjustable

motor stand.

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