13-02-2013, 04:39 PM
POWER TRANSFORMER OVER-CURRENT PROTECTION BY
MICROCONTROLLER BASED RELAY
POWER TRANSFORMER OVER.pdf (Size: 409.56 KB / Downloads: 64)
INTRODUCTION OF PROJECT:-
The Project Entitled “POWER TRANSFORMER PROTECTION USING
MICROCONTROLLER-BASED RELAY” designed with Peripheral Interface
Controller (PIC 16F877A). Utility companies have enormous amounts of money
invested in transformers of all types, including distribution and power transformer.
Operating, maintaining, and inspecting all power transformers are not an easy work.
In order to reduce burden on maintenance of such transformers a new idea has been
discovered.
This project is mainly used to protect the transformer from getting worn out due
to electrical disturbances. The electrical parameters like current, voltage of the
transformers are fed as base values, using a keypad to the Peripheral Interface
Controller and the output signal is provided to operate a relay by comparing the base
values with the operating electrical parameters. The application consists of a board of
electronic components inclusive of a PIC 16F877A microcontroller with
programmable logic. It has been designed to work with high accuracy. The electrical
parameters of the power transformer such as voltage and current are fed to the
Peripheral Interface Controller as base values. The voltage and current value during
the operation of the power transformer is monitored and fed to the controller. These
values are monitored using a LCD display. By comparing these values the Peripheral
Interface Controller produces a trip signal which operates the relay and in turn the
connectivity between main supply and the power transformer is cut off, thus
protecting the power transformer from malfunctioning.
OBJECTIVES OF PROJECT:-
The objectives of this project are;
I. To design and fabricate over current protection relay using PIC micro
controller which can operate on the permissible conditions by setting the
over current value.
II. To test unwanted conditions (over current) and when such conditions
arise to isolate the fault condition in the shortest time possible.
PROTECTION SYSTEM OF TRANSFORMER
INTRODUCTION:
The protection system of transformer is inevitable due to the voltage fluctuation,
frequent insulation failure, earth fault, over current etc. Thus the following automatic
protection systems are incorporated.
Over current relays:
An over current relay, also called as overload relay have high current setting and are
arranged to operate against faults between phases. Usually provides protection against phase -
to-phase faults and overloading faults.
TRANSFORMER – DEFINITION
A device used to transfer electric energy from one circuit to another, especially a pair
of multiple wound, inductively coupled wire coils that affect such a transfer with a change in
voltage, current, phase, or other electric characteristic.
THE UNIVERSAL EMF EQUATION
If the flux in the core is sinusoidal, the relationship for either winding between its
number of turns, voltage, magnetic flux density and core cross-sectional area is given by the
universal emf equation (from Faraday’s Law):