1. In monitoring & controlling of power systems such as Transformers, Generators, Motors etc.
2. To analyze the performance of electrical machines.
3. Can be used as a safety device to protect machines from over loading, excessive voltage etc.
4. To make the power distribution system efficient.
5. Recording device/Line parameters.

Introduction

This unit is used to protect heavy electrical machinery from damage caused by over loading. Over heating excessive voltage etc.

The unit works as a fuse so disconnect the device or m/c from circuit when detects abnormal condition & after a fixed time (for over loading )/ or when conditions gets normal it automatically reconnects the unit or m/c to circuit.

Now if it detects the abnormal condition again it repeats the process again for a number of time & if condition does not get normal, it disconnect & locks the m/c.

We are also providing the facility of password protection so m/c will not run after locking without entering password.

Auto Recloser

In our project we designed a circuit which contains a micro controller which collects the data from sensors placed at different locations of device & display them into LCD.

Now after collecting the data micro controller compares them with standard values (pre defined for each sensor on normal working conditions) & if it detects deviation from normal values it gives a buzzer sound & if it crosses the maximum limit it trip off the unit for a fixed duration & records the collected data into EEPROM.
Now if the number of tripping exceeds the 10 no. it  permanently trip the unit & starts them only after detecting the password.

The utility of this circuit are:

1. To warn the manufacturer at the initial stage of fault so that manufacturer can take proper corrective action before serious damage to device occurs which saves a lot of money required to reconstruct the device and other associated losses.
2. Performance observation of the device.
3. Monitoring of the device.

Block Diagram Explanation

A) Sensors:

This is the part of circuit which senses the different parameters of the unit.
To make the circuit unit independent it is necessary to use a conditioning unit between sensor & multiplexer. The conditioning unit will automatically maintain the output level of signals between desired limits.

B) Multiplexer:

This is required to select sensors one by one for analog to digital conversion of their values (output). When we are using single ADC the multiplexer must be analog in nature because we have to connect the analog signals.

C) A/D Converter:

This unit converts the analog signals coming from multiplexer in to 8bit parallel digital data which is a must for Micro controller operation because Micro controller can not work with analog signals directly.

D) Micro controller:

As the name indicates this unit has the over all command of all blocks or this unit decides  when to use & which unit has to be used. Since it is a programmable device it provides the facility to update the device without changes in hardware & it also reduces the hardware required to implement the circuit.

E) LCD Display:

Display plays an important role whenever we want a user friendly system because user can see & read the information from display & can get better understanding about the system. Since we want to display alphabets for massages & digits for readings we required a alphanumeric LCD display so we use a 16 character , 2 line display best suitable for our requirement because our massage length to not greater then 16 character, so they can be displayed on single line only.

F)  EEPROM R/W

As we consider a SIM it’s a memory card or ROM   which can be erased electrically because many EEPROM requires different voltage levels to program, we need a voltage level shifter or Converter to interface it with microcontroller which have only two level outputs 5VDC & 0V DC.

G)  EEPROM

It’s a two terminal memory device which stores the Information about the energy in a predefined format it contains 10, 8bit number interrelated by some mathematical function so that it can  not be charged by unauthorized persons although we have used here a chip which can be used for 256 bytes of memory so that in future we can incorporate some additional features also in same card.

H) Key Pad

This section consist the keys one to reset the controller & other one to provide the password.

I) Indications & Beeper

Although we are using here a LCD display to display the information but it is still requirement of a system that it should create the special attention of user to read same specific information on LCD this is done by this block. It generates a beeping sound on over loading mode. So that user need not to read the LCD frequently (when not required).

J)  Relay & tripping unit

To disconnect the supply when tripped.

The post Heavy electrical device protector first appeared on Student Projects.

Pin configuration of a seven segment display:

LED’s are basically of two types:

1. Common Cathode (CC)
   All the 8 anode legs uses only one cathode,  which is common.
2. Common Anode (CA)
   The common leg for all the cathode is of Anode type.

For the discussion purpose, we use CC LED, where by just reversing the logical voltages we can implement the same for CA LED also.

In a CC LED, all the 8 legs (‘a’ through ‘h’) are of anode type and the common cathode will be connected to the GND of the supply. By energizing any of the legs with +5 Volts will lead to switch the correspondent segment ON. In the microprocessor binary system, 0Volts will be considered as Binary 0, and 5Volts will be considered as Binary1. Considering these two condition, we can make an arrangement as the microcontroller gives OUT the 0s and 1s through its ports, which is connected to the 8 legs of the LED. Of course, we can control the Port Output; implicitly we can Switch-ON required legs of the display.

There 2 methods of interfacing LED with the Microcontroller Intel 8051/8951.

1. Using lookup table. This uses 7 output pins of microcontroller
2. Using 7447 decoder. This method uses 4 output pins of microcontroller

The difference between the two main methods is simple and clear. In both the cases, microcontroller communicates with external world through its ports. But, in the 1st case, we connect all the 8 pins of the port directly to the LED and control the voltage through the ports manually to display the desired number.  But, in the second case, we send the BCD of the number that we wanted to display to a middleware IC 7447, the BCD to LED code converter, which by itself gives out the correspondent 7 segment codes to the LED.

Here we explain using lookup table. Click here for the method “using 7447 decoder”

Using Lookup Table:

As we discussed, this method uses the port of the microcontroller to display the desired number. The common cathode pin is connected to GND by external wire, if it is the CC LED and in the case of the common Anode LED, the Anode pin is connected to +Vcc. Here, other pins of the LED are connected to Port 2 of 8951. A table will be prepared which relates the BCD code to the LED display code (pattern). We call it as Lookup table. The table below explains how we construct the Lookup table. Circuit diagram is given below.

Circuit diagram for Common Anode 7-Segment Display:

Circuit diagram for Common Cathode 7-Segment Display:

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The idea is whenever any engine observes a red signal on its track it will start decreasing its speed gradually and stops automatically at some distance from the signal pole. After then when it gets green signal the driver can manually start the train and go on. In the mean time when train has not stopped yet and a red signal becomes green then it crosses the signal pole with low speed and then driver can slowly increase the speed.

So now before the driver observes the red signal the engine itself observes it and automatically starts decreasing speed and then stops. The driver can feel relax in driving because he doesn’t have to take care about red signal. Even if he forgets to take any action on red signal then also we can avoid accidents by the implementation of this idea.

General description:

What we have to do is we have to attach a transmitter with signal pole which will start transmitting signals only when the red light is on. If there is green light no transmission. The engine has a receiver which catches these transmitted signals and takes desire actions.

Both the transmitter and receiver are of RF type with minimum range of 2 Km. so that train can get enough time to decrease its speed and stop before the signal pole with minimum swapping distance of 100-200 mt.

Here in our project we have used IR transmitter and receiver instead of RF for demo purpose. But same idea can be easily implemented with RF also with a little more cost.

Lets first discuss the demonstration model.

Demonstration Model:

The train engine runs on 24V DC motor so that we can easily vary its speed by varying applied voltage. The switching voltage is applied in step of 18 V, 15 V, 12 V and 9 V (min speed). The 230 VAC is step-down to 24 VAC by 12-0-12, 2 Ampere step down transformer. As shown in figure this 24 VAC line runs parallel with track at the top of the train. Movable tapping are taken from this line and fed to the internal circuit of engine. These tapping slides as the train runs on the track and give continuous supply to circuit. The IR sensor is placed at the top of the engine, senses the signals transmitted by IR transmitter attached to signal pole. Train track is straight and 20 ft long. Signal pole is placed at the end of track and train starts from farther end.

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The control panel, i.e. the main control unit of the system which consists of the primary control switches, pump indicator, siren and level indicators. The visual example of how switches And the indicators can be placed as shown the figure below.

In the figure shown above there are total of nine LEDs, four of which indicates the water level in the tank, another four indicates the water level in the sump and one LED indicates whether the pump is ON/OFF. It also consists of three switches.

1. Switch 1 is the main power switch which is used to activate the system.
2. Switch 2 is used to select whether to operate the pump in AUTO or MANUAL mode.
3. Switch 3 comes to picture only when the system is operated in MANUAL mode. It controls the direct activation of the pump.

Description :

This system is built around an 8951 microcontroller and the circuit diagram is as given below.

As you can see in the above diagram, port 0 is exclusively used as an input port which takes the information regarding the water level in the sump as well as in the overhead tank.

Port 1 is used as output port which is connected to the indicator that indicates the water level in both the tanks.

Port 2 is used as in/out port, it takes the input from switch 2 and switch 3 and gives the output which is connected to pump indicator, siren and the relay which controls the switching of the pump.

Working of the system:

There are two modes of working for the system

1. Manual mode
2. Auto mode

Which is controlled by switch 2 (refer control panel diagram)

Manual mode:

When the system is active and in manual mode, it only indicates the water levels in the tanks and it doesn’t control any working of the pump. To activate the pump in manual mode switch 3 is used.

In this mode the operator should manually control the working of the pump. As in case  if the tank is full, operator should switch of the pump which is not the case when compared to auto mode.

Auto mode:

When the system is active and in auto mode, it only indicates the water levels in the tanks and it controls the working of the pump.

The post Water level indicator cum controller first appeared on Student Projects.

Introduction to Programmable number lock system:

The system has three units, namely:

1. Keyboard unit.
2. Display unit.
3. Control unit.

The keyboard unit consists of 9 number keys, 1 unlock key and 1 lock key. These are all push button switches. This unit is used to select the desired device and to enter the codes into the system. It is also used to request the system to lock/unlock the selected device.

The display section contains 5 seven segment display. This unit displays the device number and the code entered. This section is detachable. If detached it does not affect the working of the whole system. This unit also contains password reset button and an LED to indicate the error when the device is   already locked and user wants to lock the device again. The error indicator also indicates an error when the system is already unlocked and the user tries to unlock the same.

The control unit  is the heart of our system. It contains the necessary circuitry for the control of the device .This unit controls 9 devices, which is lock/unlock  by selecting it using the keyboard and entering the password. If the code entered to unlock the device is wrong, then a silent alarm is triggered .The keyboard unit and the display unit are connected to this unit.

All these three units are merged together to form the whole system.

Block diagram of Programmable number lock system:

Working of the system:

When the system  is initially installed the reset button is pressed. This key is present in the control unit. This unlocks all the devices. This is to avoid undesired functioning of the system.

To lock a particular device the device number is selected using the keyboard. Once the device is selected the user has to press the lock key present in the keyboard. Now the device waits for the user to enter the the code. The user can enter a 4 digit number using the keyboard as per his desire. Once all the 4 digits are entered the system electronically locks the selected device.

In the same manner to unlock a particular device, the device number is entered using the keyboard. Once the device number is selected the code for the selected device is entered. If the entered code matches the code that had been entered while that particular device was locked then the selected device will be activated (unlocked). If the codes do not match each other a silent alarm will be triggered (a LED placed in the control section. Shown in figure 3).An error indicator (placed in the display section) is provided if any user tries to lock a device which has already been locked or vice versa.

If the user is half way entering the code or has done an error while entering the code and wants to start over all again then a reset button is provided in the display section. By pressing this button the user can start from entering the device number and so on.

The number of devices which the system can control can be increased by addition of a few components in the control unit. More security can be achieved by increasing the number of digits in the code. This can be done by minor changes in the program. The system uses the internal RAM of the 8051 to store the code and hence puts a lower limit to the number of digits in the code and also the number of devices the system can control. Once the system is installed only the display unit and keyboard unit will be accessible to the user. Access to the control unit should be provided only to an official personal since it contains the system  reset button.

The post Programmable number lock system first appeared on Student Projects.

1. Arithmetic instructions
2. Logic instructions.
3. Data transfer instructions.
4. Boolean variable manipulation instruction.
5. Program and machine control instruction.

We have listed all the instructions of  microcontroller with description, Bytes, Cycle. Each instructions are explained in the next pages one by one.

All instructions are explained in the next pages.

The post 8051/8951 microcontroller Instruction Set first appeared on Student Projects.

A Brief Description:

This a simple project with efficient hacking prevention from Brute Force etc. The basic user lock is of 5 Digits and Master Lock is of 10 digits so its not easy for an intruder to break the lock unless you keep the code simple.

The input is taken from a 4×3 Keypad (please see the schematic for more information) and Display the user input on a 2×16 LCD. A pin is assigned as output for activating and deactivating the lock. For demonstration i have connected an LED to that pin.

From user side:
The user has two options either he/she can use its own 5 digit code or use the default 5 digit code. If user has to do setup his own code, then he has to enter “12345” and press ‘#’. After this.. controller will ask for 10 Digit master password which is preprogrammed in the controller. Entering master lock, user can enter the new 5 digit code for the lock and press ‘#’ to save it.

Using the Keypad:
Keypad has 12 keys (4×3) starting from 1,2,3,4,5,6,7,8,9,*,0,# (please see the schematic for layout). Numeric keys are used for entering numbers. ‘*’ is used as the Cancel key and ‘#’ is used as the Enter key.

Circuit Diagram:

Download File Information:

1. LCD.C – 4-Bit LCD Drivers
2. LCD.H – LCD function prototypes and other declerations
3. Lock.C – code for lock functioning
4. LOCK.H – lock function declarations
5. KEYPAD.C – Keypad drivers
6. KEYPAD.H – Function declarations
7. DELAY.C – Delay Functions
8. DELAY.H – Function Prototypes only
9. MAIN.C – Main function!
10. Digital Code Lock Schematic – PDF file of orcad schematic

Download the source codes by clicking here

By Ajay Bhargav
http://rickeyworld.info

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