Download ONLOAD TAP CHANGER OF THE TRANSFORMER

ONLOAD TAP CHANGER
The block diagram consists of the potential transformer, precision rectifier,
ADC, micro controller, display, triac array and transformer.
Higher KVA transformers will measures the output voltage according to the
voltage it will switch on triac array and maintain constant voltage. First the voltage of the
secondary of the transformer is measured with the help of a potential transformer. This
potential transformer will step down the power supply voltage (230Vto 440V) level.
Then the secondary of the potential transformer will be connected to the precision
rectifier, which is constructed with the help of op–amp. The advantages of using
precision rectifier are it will give peak voltage output as DC; rest of the circuits will give
only RMS output.
Then the rectified output will be given to the micro controller through Analog to
digital converter. ADC will convert the analog voltage into digital data and then it will be
given to the micro controller, the ADC is an eight channel eight bit ADC. Then the
appropriate thyristors will be switched ‘on’ or ‘off’ to get exact voltage. Here we are
using the triac array circuit. The triac array is used to select the required voltage of the
transformer. Based upon this selection, we will get the required voltages in the output
circuit
TRANSFORMER:
A transformer changes (transforms) an alternating voltage from one value to
another. It consists of two coils, called the primary and secondary winding, which are not
connected electrically. The windings are either one on top of the other or are side by side
on an iron, iron-dust or air core.
RECISION RECTIFIER:
An absolute-value circuit, or full-wave precision rectifier, can be implemented by
summing the output of a half-wave rectifier and its input with the proper phase and
amplitude relations.
ANALOG TO DIGITAL CONVERTER:
The ADC represents the analog to digital converter, which can very easily be
interfaced with any of the micro controller. This type of converter changes the analog
voltage input V in to an 8-bit digital output (D7-D0). A pulse applied to the ADC’s
START conversion terminal initiates the conversion process. The completion of
conversion takes an amount of time depending upon the method of conversion time can
be as large as 100ms for some ADC.
Display
Potential
transformer
Precision
rectifier
ADC
Micro
controller
Transformer
Triac array