Automated Star Delta Connection Switching System

The assignment details a project on developing an automated system to switch between star and delta connections for induction motors. The goal is to reduce starting current and save electricity by implementing a smart switching control system using relay switches and a microcontroller. The team worked together under the lead of the assistant professor, managing milestones and activities within expected schedules.

COMPETENCY
DEMONSTRATION
REPORT
Career Episode 3
MD IFTAKHAR HAQUE KHAN

CE 3.1 Project Information
Name of the project: Automatic Star Delta Starter Using Relay and Adjustable
Electronic Timer for 3 Phase Induction Motor
Location of the project: [PLEASE FILL]
Project Duration: [PLEASE FILL]
Organization: [PLEASE FILL]
Role and Designation during the time: Team Member
CE 3.2 Project Background
CE 3.2.1 Characteristics of the project
Most of the industries nowadays are using the three-phase induction motor for the
accomplishment of the operational activities within the industry. I had developed an approach
that can be helpful in reducing the starting current of the motor as it consumes high current for
being started. I used the electronic timer and relays that will be making it possible for enhancing
the start-up current during the starting phase. These electronic devices are helpful in switching
the power supply and mode of operation of the induction motor during the starting phase of low
current drawing to the full load drawing current.

CE 3.2.2 Objectives developed for the project
In manner to accomplish every activities in an effective and efficient manner, it is
necessary to develop real world objectives and goals. I tried to manage the scope of the project
through developing following goals and objectives:
 To effectively setup the instant switching mode from star to delta and vice versa
 To implement microcontroller for controlling the switching process automatically
 To save energy and provide a product that can contribute in making it happen
 To manage the budget low without hampering the quality and output of the project
CE 3.2.3 My area of work
I was commanding the whole team as a leader and I had tried to manage their roles in the
project through assigning jobs to the team members. I tried to manage the project constraints as it
was planned during the planning phase. I had supplied 415 V AC to the three single-phase
transformer of rating 230 / 12 V output. Voltage is supplied to the printed circuit boards from
one of the connected transformer passing through three bridge rectifier sets in manner to be
operated at 12 V Dc relays. I had also utilized the same output for supplying the microcontroller
89C 2051passing the connection through 7805 voltage regulator that can be utilized for obtaining
5V DC output from rest of the transformers. This transformer stepped down the voltage to 12 V
DC that is then supplied to the microcontroller for automatically operating the switching controls
of the star and delta connection. Following is the design setup for the completing the circuit of
the proposed model:

Figure 1: Circuit Design

CE 3.2.4 Project Group
CE 3.2.5 My responsibilities throughout the project
I had to deliver the project in a successful and cost effective manner through considering
many application of the project. Since, induction motors are mainly used in the industries; it can
be revolutionary product at marginal price that can be offered to the industries for minimizing
the cost spent on the electricity. I kept the complexities mile apart from the project and used
simple relay and microcontroller for switching the connections between star and delta. I
supervised the whole project during the development of the project and inspected it after the
completion of the whole setup. I had listen to everyone’s perspective while delivering the project
and implemented all the demands that they had in mind and were expressed during the meetings
at the regular interval of time.

CE 3.3 Distinctive Activity
CE 3.3.1 Comprehending the theory of the project
The traditionally direct starters are not capable of providing protection to the induction
motor against single phasing and voltage fluctuation, as the induction motors are highly sensitive
to these parameters. I had designed the project for providing low voltage to the induction motors
that was achieved by the application of Delta / Star starters as these are the most efficient voltage
starter within the industry of the 50Hz industrial applications. This starter can allow the supply of
low current at the starting phase and thereafter applied the full load current to the induction after
a while. I applied the principle that the motor started as star will be resulting in the low voltage
supply to the motor that is root three times the phase voltage. Thereafter if the motor runs at
delta, the voltage will be same as that of the phase voltage and hence, the motor will be running
at it full voltage.
CE 3.3.2 Engineering knowledge and skills applied in the project
I had done the mathematical calculation for the determination of the phase voltage, phase
current, and line current in both star and delta connection:
Star Connection:
Phase Voltage Vs = 3 Phase Voltage = V1 x 1/√3
Phase Current IS1 = Phase Voltage Vs / Z = √3 x V1 / 3Z
Line Current = Phase Current IS1 = √3 x V1 / 3Z
Delta Connection:
Per Phase Voltage Vs = 3 Phase Voltage V1

Phase Current IS2 = Phase Voltage Vs / z = V1/ Z
Line Current = √3 x Phase Current IS2 = √3 x V1 / 3Z
CE 3.3.3 Accomplishment and task performed
I had designed the circuit of the developed project and implemented the electrical
components of the project as described in the above figure. I had supervised the whole project
growth and identified the issues explained in the next paragraph during the execution of the
project. I set the paths for the execution of the project and every team member had to follow the
path for the successful execution of the project.
CE 3.3.4 Identified issues and their solutions
3.3.4.1 Issues
I identified that the current drawn for the start-up of induction motor is very high that
does not need any more when the motor retains its full voltage stage. I had also identified that the
connections cannot be switched manually or any other way, an automatic process was needed for
the successful execution of the project.
3.3.4.2 Solutions
I used the relays and microcontroller for the development of an automated system that
can be helpful in switching the start delta connection after the minimum time difference of about
3 seconds. I installed the microcontroller for providing automation to the switching control and
that can be utilized for limiting the current during the start-up phase and thus, after that limiting
the full load voltage.

CE 3.3.5 Plan to produce creative and innovative work
Many attempts had been delivered in the early ages for the execution of this operation
however; many of them were lagging on certain factors. I had implemented the relay switches
and the microcontroller for the processing of the automatic switching control of the star delta
connection. I had utilized the fact of the relation between the phase voltages and line current of
both the connections and extracted the necessary output from the project. I kept the time delay
between the switching of the Star / delta connection and switching procedure. I read many
research papers and research reports of experienced electrical professors and tried to use their
ideas with adding my pinch of innovation.
CE 3.3.6 Collaborative work
My team was a group of five members that includes the assistant professor, team leader
and three members. I was playing the lead role and I tried to manage the roles and activities of
each member involved with the project. Assistant professor guided on the matters that need for
consideration while delivering the project. I managed the activities through differentiating the
projects within different milestones that needed to be completed within expected schedule and so
motivated the team members to achieve the project constraints as per the directions and
suggestions.
CE 3.4 Project Review
CE 3.4.1 Project Overview
Induction motors are the most applicable machines utilized within the industries, due to
its many advantageous factors and is the most applicable motors in Bangladesh. I took the

starting current and full load current of the induction motor as a topic of concern and thus, I
delivered this project in manner to provide a model that can switch the controls of the star / delta
connections. This project will not only protect the induction motors from burning itself rather, it
will be a helpful measure for saving electricity. I tried to manage the budget of the product low
in manner to be applicable in most of the industries.
CE 3.4.2 My contribution to work
I leaded the team towards successful accomplishment of the objectives and constraints of
the project and my team deliver them as per the planning. I contributed in the development of the
circuit and implementation of all the electrical and electronic components needed for controlling
the switching of Star / Delta connection. I done the mathematical calculations for the
determination of the phase voltage and line current for the proper implementation of the
switching control. I also contributed in the identification of the problem and the solution
applicable as per the identified problem that lead to the successful delivery of the project.