Modern petrochemical plants are always at the risk of fire since lot of toxin inflammable gases are often present, the temperature is also high . These are normally ums class
(unmanned machionery space). Supervisory rooms are always away from the actual plant. All light fixures are explosion proof.
Little spark can cause great fire. Normal fire sensors can not be used. Special designed sensors are used. In case smoke enters into the sensor & sensor get activated ,
The following action will take place
1) Sounds an fire alarm to attract attention .
2) If the reset SW is not pressed within 30 seconds, the projects takes further action,
3) Shut down the plant,
4) Start sprinkling,and
5) Make an emergency call to , deliver an emergency message .
6) It will call five times at the interval of one minute and again check for the smoke, if smoke is still present it will continue to do so otherwise start monitoring again.
This project is based on 8051 microcontroller.(IC2)
IC3 is 74245 and is used as buffer.
IC4 P89021 is a one time programmable(otp) chip where messages are stored. This is 21 second speech ic where total of 12 messages can be recorded on eight different locations, but total duration should not be more than 21 seconds. recorded messages can be played back by setting the trigger pin 10 & 11 high, making these pin low will stop the message, Setting these pin high will repeatedly replay the same message.
Ic Lm 386(IC5) is an audio amplifire . Audio output from speech IC4 pin 7 cout is coupled to this ic on pin 3 through VR2 volume control and C10. Amplified output from pin 5 drives the speaker through capacitor C14. R14 and C13 are for tone correction.
C16 and C17 couples the audio message to telephone line .
C11 connected to pin no 6 of IC5 is filter and C12 is noise suppressor.R26 is current limiting resistor. C15 is for noice rejection
IC4 needs 3.3v operating voltage .R9 is a voltage dropping resistor, D7 is 3.3v zener diode and C7 iS a filter capacitor. These components will always maintain the voltage to3.3v at pin 9,12 of IC4. capacitor C8 is a feed back capacitor.,C9 and R13 connected to pin no 7 of IC 4 are tone corrector.R12 along with the VR1 variable resistor performs the sampling rate adjustment. R10 and R11connected to pin26 and pin 27 of the microcontroller are current limiting resistors.
R15 and R16connected to the base of transister Q1 and Q2 are voltage dropping resistors. Transistors Q1 & Q2 drives the relays, when to set high logic by microcontroller. Q1 Drives the dial relay RL1and Q2 drives the off-hook relay. RL2.
RL3 is a plant ON/OFF relay and RL4 is sprinkle relay. Q3 drives the RL3 through resistor R28 and Q4 drives the sprinkle relay through R29 resistor.
IC3 acts as buffer, R3 TO R8 are current limiting resistors and drives indication leds LD2 TO LD7 when PORT1 pins are set to low logic.
4×3 matrix keyboard is connected to PORT3 .keyboard is used to store the emergency telephone number .
PORT0 has open source internally so we have connected 4.7kX8 SIL,pullup resister to make them digital i/0 pins .This port is used as input port all the sensors are connected to this port.
PGM SW is connected to p2.0 pin(21) of PORT2 is input pin this switch is used to store the telephone number. SW1 is alarm stop switch connected to pin22 (p2.1)of the microcontroller,used as input pin. Port2,pin number 24,25,26 and 27 are used as output pins
All the input PORT pin logic state is normally high and they are active low.
All the output PORT pin logic state is normally low and thay are active high pin.
Port1 pins are normally high and they are active low;.
Circuit is driven by 9v 1 ampere transformer connected to PCON1
Diode D1-D4 forms bridge circuit C1 ,C2 are filter capacitors,C3 is for noise filter.
Ic 7805 is 5v regulator ic to give stablised supply to microcontroller. Ld1 is a power indication led R1 is current limiting resistor.
Crystal X1 along with C5 and C6 gives the necessary clock to microcontroller.
Capacitor C4 and R2 gives the required reset pulse to microcontroller.RST SW is master reset switch.
Resistances connected to indication leds are current limiting resistors
Resistances R18 to R25 are current limiting resistors.