IMPLEMENTATION OF AN AUTOMATIC INDUCTION MOTOR STARTER WITH DELAY USING MICROCONTROLLER

IMPLEMENTATION OF AN AUTOMATIC INDUCTION MOTOR STARTER WITH DELAY USING MICROCONTROLLER

Electrical and Electronics Project by Ravi Devani

ABSTRACT

It is well understood that induction motors draw higher currents during their starting operations than is the case under full load running conditions. Since the early days of induction motor availability, starting methods other than Direct-on-Line have been used, and in some cases mandated by Utilities, to reduce the effect of these high starting currents on the electrical distribution network. What is generally not recognized is the existence of short duration inrush currents, which greatly exceed these starting currents. Furthermore, the introduction of complex starting methods to reduce starting currents is often compromised by other unanticipated inrush currents introduced by the starting system itself, unless special precautions are taken. This paper implements a device that protects three phase induction motor from inrush currents on the distribution system, as well as on the motor protection components using PIC16F84A Microcontroller.

Keywords: Induction Motor, Microcontroller, motor protection, currents, MPLAB, Direct on line, distribution system.

INTRODUCTION

Induction motors are popular due to their low-cost, sturdy construction, fast pick-up, low maintenance expenditure and good efficiency. The DOL (direct-on-line) starters and star/delta starters used for starting and running of induction motors provide coarse type of protections against voltage fluctuations and single phasing. Induction motors are very sensitive to low voltage and single phasing during which they draw a heavy current and can burn out unless switched of within few seconds of occurrence of such conditions. This makes the requirement of a sensitive protective device essential to avoid burning of induction motors under such conditions. The circuit of an automatic starter, incorporating the important features given below, is described here. It is meant to be used in conjunction with a DOL starter. Automatic start on resumption of proper conditions Single phasing prevention 24-hour programmable off timer (on completion of actual runtime of the motor). An induction or asynchronous motor is a type of AC motor where power is supplied to the rotor by means of electromagnetic induction, rather than a commutator or slip rings as in other types of motor. These motors are widely used in industrial drives, particularly poly-phase induction motors, because they are rugged and have no brushes. Single-phase versions are used in small appliances. Their speed is determined by the frequency of the supply current, so they are most widely used in constant-speed applications, although variable speed versions, using variable frequency drives are becoming more common. The most common type is the squirrel cage motor.

METHOD

The block diagram of the system is depicted in Fig. 1.0. The embedment of a microcontroller into the system makes it a standalone system that is capable of taking decisions to keep the system functioning properly. The microcontroller receives inputs signals from the three phase mains which is been step down by step-down transformers, depending on the input the microcontroller receives, it either takes decision to switch on the relays or switch off the relays.

Fig.1.0: The automatic induction motor starter with programmable timer

When the system is first switched on, it waits for 30 seconds to make sure the power source is stable and starts monitoring. By switching ON or OFF of the relays, the microcontroller also turn on LEDs and the color of LED, being lit ON, indicates which the three phases is ON or OFF. The schematic diagram of the automatic three phase direct starter controller system is given in Fig. 2.0. The microcontroller used for the project is the PIC16F84A [5]. The microcontroller takes inputs from the three mains continuously via step-down transformer. Under the control of the program written in the microcontroller’s memory, the microcontroller turns either Red or Green LEDs and turns the three relays ON or OFF.

Fig. 2: Complete Circuit diagram of a Three phase Induction Motor

Electrical and Electronics Project by Ravi Devani

The transistors are turned on depending on the state of each AC supply phase. The voltage at each phase determines which of the transistor will trigger on. Using the requirements for the saturation of the BJT expressed as

Under the Condition in equation 1, the transistors (Q1, Q2, Q3, Q4, Q5, Q6, Q7) will turn on.

The transistor (Q) will turn on when

Since we are using transformer of 240/12 volts and need a voltage of 5volts (nominal input voltage of microcontroller) Figure 3.0 gives the flow chart of the program executed by the microcontroller. As indicated in the flow chart the microcontroller polls the input.

Fig.3: Flow chart of the three induction motor starter with

automatic programmable timer 

RESULTS AND DISCUSSIONS

The program for the microcontroller was written in Assembly Language which is attached as Appendix 1 and was then built into an executable Hex file using the MPLAB IDE Version 8.50 and the embedded MPASM assembler. A software simulation was carried out with the simulator built into the MPLAD IDE to ensure that the program variables and registers changed as desired. The program required few registers but the output ports (PORTA and PORTB) were observed to have the correct values. The circuit shown in Fig. 2.0 was then built in Vero board, which was tested using three phase ac mains and the output was connected to 220 V, 100 Watts bulb. The microcontroller program was observed and it gave the required outputs.

Table 1: Sensor Conditions and Microcontroller Decisions

Note that in Table 1, L = Low Logic Level Signal and H = High Logic Level Signal, P1 = Phase 1, P2 = Phase 2, P3 = Phase 3

CONCLUSION

An automatic over and under voltage protector system has been implemented using induction motor starter which is necessitated by the need to monitor the voltage supply to equipments and appliances and consequently protect them from the danger of being damaged due to voltage fluctuation. Based on the theoretical analysis, design and testing of this work, the following conclusions are made:

1. Since switching is automatic, the device is no doubt being used as an automatic voltage protector.

2. The display of the monitored voltage is indicated simply by LEDs, which can be easily seen and understood by all.

3. The assembly unit is very compact and portable and can be easily incorporated into appliances or equipments.

4. The cost of constructing this project is relatively low  as compared to the important function it performs.

It can therefore be easily commercialized.

REFERENCES

[1]. Agbo, O. D and G. J. Liambee, Design And Construction Of An Automatic Overvoltage And Under voltage, Electrical and Electronic Engineering Department, University Of Agriculture, Makurdi (Unpublished).

[2]. http//www.opamp.htm.Operational Amplifier Basics (01/11/2008).

[3]. MPLAB IDE User’s Guide, 2004. Microchip Technology Inc, 2355 West Chandler Blvd., Chandler, Arizona, U.S.A.

[4]. MPASM Assembler, MPLINK Object Linker, MPLIB Object Librarian, Microchip Technology Inc, 2355 West Chandler Blvd., Chandler, Arizona, U.S.A.

[5]. User’s Guide, 2005. Microchip Technology Inc, 2355 West Chandler Blvd., Chandler, Arizona, U.S.A.

[6]. MPLAB PM3 Programmer User’s Guide, 2006. Microchip Technology Inc, 2355 West Chandler Blvd., Chandler, Arizona, U.S.A.

[7]. Okolo I. K. Design And Construction Of A Digital Distance Device Using A Microcontroller, Electrical/Electronic Engineering Department, University Of Agriculture, Makurdi, (Unpublished).

[8]. PIC16F84A datasheet, 2006. Microchip Technology Inc, 2355 West Chandler Blvd., Chandler, Arizona, U.S.A.

[9]. Theraja, B. L and A. K. Theraja, A Text Book Of Electrical Technology. S. Chand Company Ltd. New Delhi, pp. 851-918, 2001.

[10]. Fernando, E. V, Peres and P. A. Ramon,. Microcontrollers “Fundamental and Applications with PIC.” CRC Press, Taylor and Francis Group, New York, 2009.

[11]. 2SC4204 NPN transistor datasheet, 2005. Sanyo Electric Co. Ltd, Tokyo, Japan.

Electrical and Electronics Project by Ravi Devani

APPENDIX 1

Assembly Programming Language

;Author         : AGBO

;File Name    : A_IM_STARTER.asm

;TITLE  : "INDUCTION MOTOR STARTER WITH AUTOMATIC TIME DELAY "

;Date             : 3RD NOV. 2012

;Version        : 1.0

;Debugged    : 29 NOV. 2012

;*********************************************************

;********Processor Declaration and Configuration*************

PROCESSOR PIC16F84A

#Include "p16f84A.inc"

__CONFIG _CP_OFF & _WDT_OFF & _PWRTE_ON &_XT_OSC

ORG 0x00

BCF STATUS, RP0      ;

CLRF PORTA          ; Initialize PORTA by clearing output data latches

BSF STATUS, RP0      ; Select Bank 1

MOVLW B'11111111' ; Value used to initialize data direction

MOVWF TRISA          ; Set RA<5:0> as inputs.

BCF STATUS, RP0     ;

CLRF PORTB         ; Initialize PORTB by clearing output data latches

BSF STATUS, RP0      ; Select Bank 1

MOVLW B'00000000' ; Value used to initialize data direction

MOVWF TRISB          ; Set RB<7:0> as outputs

START

BSF STATUS,5            ;Turn to Bank 1

MOVLW 0x00              ;

MOVWF PORTB         ;

BCF STATUS,5           ;Return to Bank 0

MAIN

  NOP

SWITCH1

   BTFSC PORTA, 0

   GOTO SWITCH2

   GOTO OUTPUT1

SWITCH2

   CALL DELAY ; CALLING DEBOUNCE

   BTFSC PORTA, 1

   GOTO SWITCH3

   GOTO OUTPUT1

SWITCH3

   CALL DELAY ; CALLING DEBOUNCE

   BTFSC PORTA, 2

   GOTO OUTPUT

   GOTO OUTPUT1

OUTPUT

   CALL DELAY20MSEC ; CALLING DEBOUNCE

   BSF PORTB, 1 ; LED GREEN ON(UNRESET)

   BSF PORTB, 2 ; ENGAGING CAR ENGINE

   BSF PORTB, 3 ; ENGAGING CAR ENGINE

   BSF PORTB, 6 ; ENGAGING CAR ENGINE

   BSF PORTB, 7 ; LED GREEN IS OFF(UNRESET)

  

GOTO START ; if it is 1 skip this instruction

OUTPUT1

  CALL DELAY20MSEC ;

  BSF PORTB, 7                ; LED GREEN IS OFF(UNRESET)           BCF PORTB, 1               ;  LED GREEN ON(UNRESET) 

  BCF PORTB, 2               ; ENGAGING CAR ENGINE 

  BCF PORTB, 3               ; ENGAGING CAR ENGINE 

  BCF PORTB, 6                ; ENGAGING CAR ENGINE 

  GOTO START

DELAY

  MOVLW .2   ;Make deld repeat two times 

  MOVWF 0x1A ; deld

  DECFSZ 0x1B,1 ;Decrement file 1B till zero

  GOTO deld ; 

  DECFSZ 0x1C,1 ;Decrment file 1C till zero

  GOTO deld ; 

  DECFSZ 0x1A,1 ;Decrement file 1A till zero

  GOTO deld ;

DELAY20MSEC

  MOVLW 0x02 ;Make deld repeat two times

MOVWF 0x1A ; deld1 

  DECFSZ 0x1B,1 ;Decrement file 1B till zero

  GOTO deld1 ; 

  DECFSZ 0x1C,1 ;Decrment file 1C till zero

  GOTO deld1 ; 

  DECFSZ 0x1A,1 ;Decrement file 1A till zero

  GOTO deld1 ; 

  RETURN

  END

GSM BASED AUTOMATIC SUBSTATION LOAD SHEDDING AND SHARING USING PROGRAMMABLE SWITCHING CONTROL

GSM BASED AUTOMATIC SUBSTATION LOAD SHEDDING AND SHARING USING PROGRAMMABLE SWITCHING CONTROL

Electrical and Electronics Project by Ravi Devani

ABSTRACT

Our aim of this project is designed to control substation load shedding and sharing using a programmable switching control by automatically.In this project we demonstrate the working of this simple operation using a Microcontroller. The development of this application requires the configuration of the program through GSM module.In substation, there are many tasks like certain loads need to be switched on/off in specific time intervals. In this, the loads can be operated in three modes: Set mode, Auto mode and Manual mode. In set mode, through timers, the operation is based on input time set by the user where as in auto mode it works on default time settings and finally in the manual mode it functions while respective loads are operated depending on the load necessity using GSM. All the modes and status of loads are displayed on an LCD.

Finally GSM modem which sending sms to the control system we can select the mode and timing remotely.

Keywords – Automation, Control System, Microcontroller, Embedded System, 8051, AT89S52, SIM300.

INTRODUCTION

Controlling of electric power substation equipments plays an important role in daily maintenance of electric power system. In an extra high voltage substation, the reliability required from substation components is critical. Applications of controlling base station with the help of mobile of substation equipments could improve the quality of accelerating the process of any substation.Our aim is to control the Substation equipments through a mobile phone.

Here we are using a GSM Based Modem technology connected end-to-end, with one end to the distribution side and other to the mobile device. The mobile device used here makes the control of equipment of the substation on a global basis. Here we are going to control the distribution side equipment Switch Gears and Relays.

METHODOLOGY USED

Our projects functionality of system involves in to following steps: In this block diagram the gsm which sending sms to the controller through max232 then the controller performs the operation by read the message (i.e.)controller gives signal to the relay driver that controls the feeder.

COMPONENTS

A. AT89S52 Microcontroller 
The AT89S52 is a low-power, high performance, inexpensive CMOS 8-bit microcontroller with 8K bytes of in system programmable flash memory. The device is manufactured using Atmel’s high-density nonvolatile memory technology and is compatible with the industry-standard 80C51 instruction set and pin-out. The on-chip flash allows the program memory to be reprogrammed in-system or by a conventional nonvolatile memory programmer. By combining a versatile 8-bit CPU with in-system programmable flash on a monolithic chip, the Atmel AT89S52 is a powerful microcontroller which provides a highly flexible and cost-effective solution to many embedded control applications. 

B. Level Shifter IC MAX232

The MAX232 is an integrated circuit that converts signals from an RS-232 serial port to signals suitable for use in TTL compatible digital logic circuits. The MAX232 is a dual driver/receiver and typically converts the RX, TX, CTS and RTS signals. The drivers provide RS-232 voltage level outputs (approx. ± 7.5 V) from a single + 5 V supply via on chip charge pumps and external capacitors. The receivers reduce RS-232 inputs (which may be as high as ± 25 V),to standard 5 V TTL levels. These receivers have a typical threshold of 1.3 V, and a typical hysteresis of 0.5 V.MAX232 IC will convert a TTL Logic 0 to between +3 and +15V, and it will convert a TTL Logic 1 to between -3 to-15V, and vice versa for converting from RS232 to TTL. 

C. Relay Driver ULN2003

Relay Driver ULN2003 is a high voltage, high current Darlington transistor array containing seven open collector Darlington pairs with common emitters. It consists of seven NPN Darlington pairs that feature high voltage outputs with common cathode Clamp diodes for switching inductive loads. The collector current rating of a single Darlingtonpair is 500 mA. For higher current capabilities, the pairs can be paralleled. ULN2003 is used to interface relays withthe microcontroller since the maximum output of the microcontroller is 5V with too little current delivery and is notpracticable to operate a relay with that voltage. 

D. Electromagnetic Relay

Electrical and Electronics Project by Ravi Devani

Relay is an electromagnetic device which is used to isolate two circuits electrically and connect them magnetically. For example, a relay can make a 5V DC battery circuit to switch a 230V AC mains circuit. Thus a small sensor circuit can drive, say, a fan or an electric bulb. A relay switch can be divided into two parts: input and output. Operating voltages like 6V, 9V, 12V, 24V etc.Input part - 2 Coil Pins : These pin are the control switch which is connected to electromagnet through which we can control the operation of relay. Here low voltage is applied to create magnetism. Output part - Normally Open Contact (NO) – NO contact is also called a make contact. It closes the circuit when the relay is activated. It disconnects the circuit when the relay is inactive. Normally Closed Contact (NC) – NC contact is also known as break contact. This is opposite to the NO contact. When the relay is activated, the circuit disconnects. When the relay is deactivated, the circuit connects.

E. LCD

Liquid Crystal Display (LCD) consists of rod-shaped tiny molecules sandwiched between a flat piece of glass and an opaque substrate. These rod shaped molecules in between the plates align into two different physical positions based on the electric charge applied to them.

When electric charge is applied they align to block the light entering through them, whereas when no-charge is applied they become transparent. Light passing through makes the desired images appear. This is the basic concept behind LCD displays. LCDs are most commonly used because of their advantages over other display technologies. They are thin and flat and consume very small amount of power compared to LED displays and cathode ray tubes (CRTs).

A 16x2 LCD means it can display 16 characters per line and there are 2 such lines. This LCD has two registers, namely, Command and Data. The command register stores the command instructions given to the LCD. A command is an instruction given to LCD to do a predefined task like initializing it, clearing its screen, setting the cursor position, controlling display etc. The data register stores the data to be displayed on the LCD. The data is the ASCII value of the character to be displayed on the LCD.

Just like most of the currently available electrical devices and home appliances, the project is powered by an on board power supply containing transformer for AC source, a bridge rectifier to convert to DC source and a voltage regulator to get 5V DC source. The power supply will provide 5V to the Atmel AT89S52 microcontroller, level shifter IC MAX232, ULN2003 Relay Driver and a 16×2 LCD module.

Electrical and Electronics Project by Ravi Devani

IMPLEMENTATION AND RESULT

The system was simulated according to the block diagram given in Figure. 

For the sake of simplicity and flexibility, instead of sending full commands like “Turn ON LOAD 1”, the user can send a single number to command. A simple formula was developed that can be used to know which number to send to turn ON/OFF any load. Load numbers can be set by the user. A single controller can control up to 28 loads.The system was simulated using Proteus v7.7 and the results found to be in the expected lines. The C program used in the system was written using Keil compiler and was added to the simulated module.International Journal of Latest Trends in Engineering and Technology (IJLTET)sss Power Supply

CONCLUSION

Our paper presents an inexpensive GSMbased interactive control system. A number of literatures related to thetopic of control systems and automation were reviewed and analyzed. According to the proposed system, the host canbe any cell phone and the client is a controller based on Atmel AT89S52. The controller is connected to a GSMmodem through an RS232 cable and a level shifter IC. The paper provided explanation of the circuit diagram of theproposed system. The project circuit diagram was designed using Proteus v7.7 designing software. Also, a prototypeof the system was assembled with the required components on a PCB (Printed Circuit Board). The proposed system is economical and efficient in comparison with the similar systems developed so far.

REFERENCES

[1]. A. Jadhav, and P. Gadhari, “Interactive Voice Response (IVR) and GSM Based Control System”. Proceedings of the National Conference "NCNTE- 2012". Mumbai. 2012 

[2]. I. Petrov, S. Seru, and S. Petrov, “HOME AUTOMATION SYSTEM”, School of Engineering Science, 2011.

[3]. D. Rudrapalet. al. “Automated Load Shedding Period Control Systems”, International Journal on Computer Sc. & Engineering, Vol 3, Issue 5, pp. 1159 - 1168, May 2011.

[4]. E. Yavuz, et al., “Safe and Secure PIC Based Remote Control Application for Intelligent Home”. International Journal of Computer Science and Network Security, Vol. 7, No. 5, May 2007.

[5]. A. Delgado, R. Picking and V. Grout, “Remote- Controlled Home Automation Systems with Different”, Centre for Applied Internet Research (CAIR), 2006.

Electrical and Electronics Project by Ravi Devani