1. VOLTAGE & FREQUENCY
MONITORING THROUGH LCD
Under The Guidence of :
V.Chatanya Prasad(M-Tech) Presented By:
Asst.Prof. EEE Department oK. Hari Kishore 08MP1A0229

2. ABSTRACT OF VOLTAGE &
FREQUENCY MONITORING
 The abstract of this project is to monitor the voltage
and frequency in single phase environment and
display it on display module.
 This is achieved with the sequential operation of the
micro controller AT mega8 and potential
transformers.
 We step down voltages with the help of instrument
transformers so that the ADC within the micro
controller can sample them.
 For frequency measurement we are using an external
circuit which produces a continuous sine wave and we
are feeding this output to MC-ADC pin then it will
calculate appropriate frequency.

3. INTRODUCTION
Embedded System
Microprocessors
Microcontrollers

4. BASIC LAYOUT OF
MICROCONTROLLER

5. BLOCK DIAGRAM OF
VOLTAGE & FREQUENCY
MONITORING

6. AT MEGA 8
MICROCONTROLLER
 The ATmega8 is a low-power CMOS 8-bit microcontroller
based on the AVR RISC architecture
 This is high-performance, Low-power AVR 8-bit
Microcontroller
 8K Bytes of In-System Self-programmable Flash program
memory – 512 Bytes EEPROM
 1K Byte Internal SRAM
 Two 8-bit Timer/Counters with Separate Prescaler, one
Compare Mode
 Operating Voltages 2.7 - 5.5V (ATmega8L) – 4.5 - 5.5V
(ATmega8)
 Power Consumption at 4 MHz, 3V, 25ºC
 Active: 3.6 mA
 Idle Mode: 1.0 mA
 Power-down Mode: 0.5 µA

7. PIN DIAGRAM OF AT
MEGA 8

8. PIN DESCRIPTION OF AT
MEGA 8
 VCC
 Digital supply voltage.
 GND
 Ground.
 Port B (PB7..PB0)
 8-bit bi-directional I/O port with internal pull-up
resistors
 Pins are tri-stated when a reset condition becomes
active, even if the clock is not running.
 PB6 can be used as input to the inverting Oscillator
amplifier
 PB7 can be used as output from the inverting Oscillator
amplifier.

9. PIN DESCRIPTION OF AT
MEGA 8
 Port C (PC5..PC0)
 It is a 6-bit bi-directional I/O port with internal pull-up
resistors
 The Port C pins are tri-stated when a reset condition
becomes active, even if the clock is not running.
 Port D (PD7..PD0)
 It is an 8-bit bi-directional I/O port with internal pull-up
resistors
 pins are tri-stated when a reset condition becomes
active, even if the clock is not running.
 RESET
 A low level on this pin for longer than the minimum
pulse length will generate a reset, even if the clock is
not running.

10. ANALOG TO DIGITAL
CONVERTER
 The ATmega8 features a 10-bit successive approximation
ADC.
 The ADC is connected to an 8-channel Analog Multiplexer
which allows eight single-ended voltage inputs constructed
from the pins of Port C.
 The ADC contains a Sample and Hold circuit which
ensures that the input voltage to the ADC is held at a
constant level during conversion.
 The ADC has a separate analog supply voltage pin, AVCC
which must not differ more than ± 0.3V from VCC
 The ADC converts an analog input voltage to a 10-bit
digital value through successive approximation.

11. POTENTIAL
TRANSFORMER
 The primary winding of the P.T. is connected across the
line carrying the voltage to be measured and the voltage
circuit is connected across the secondary winding.
 The design of a potential transformer is quite similar to
that of a power transformer but the loading of a potential
transformer is always small, sometimes only a few Volt-
amperes.
 The secondary is designed so that a voltage of 9 volts is
delivered to the instrument load.

12. CURRENT TRANSFORMER
 Current transformers measure power flow and provide
electrical inputs to power transformers and instruments.
 A current transformer (CT) is a type of instrument
transformer designed to provide a current in its secondary
winding proportional to the alternating current flowing in
its primary.
 The current transformer safely isolates measurement and
control circuitry from the high voltages typically present on
the circuit being measured.

13. CONNECTIONS OF CT & PT

14. INTERFACING OF LCD TO
ATMEGA 8

15. JHD 162A LCD PIN
CONFIGURATION

16. APPLICATIONS
 Frequency information can be used in many
areas of power system analysis, operation, and
control.
 The voltage metering is used in wide range of
applications not only for measuring but also for
controlling.
 The project constantly monitors voltage and
frequency indicating potential improper polarity
and ground wiring.
 The RMS voltage and frequency readings are
ideal for monitoring modified sine waves such as
solid-state generators, inverters and
Uninterruptible Power Supply (UPS) products.

17. CONCLUSION
 Frequency dynamics is one of the most important
measures of an electrical power system status. To
better understand power system dynamics, an
accurately measured frequency is needed.