Hardware Structure of Automatic Generator Protection FYP
Details Of Parts:
Potential Transformer (PT):
Potential transformers are instrument transformers. They are used to increase the range of voltmeters in electrical substations and generating stations. The potential transformer always used in parallel with the given source.
There are a large number of primary turns and only few secondary turns so that the voltage is stepped down from the high voltage. Which is used in generator protection circuit for a low voltage actually being measured.
Potential transformer diagram:
What will be happen when voltage is over from reference value?
Generator voltage step down by the potential transformer, controller observe it and shows voltage on LCD,
If voltage increase above the reference value controller observes it and operates the relay then load is cutoff from the generator hence generator is relaxed and over voltage display on LCD.
Current transformer (CT):
Current transformer (CT) is used for measurement of electric current and it is always connected in series.
Current transformers are commonly used in metering and protective relays in the electrical power industry.
What will be happen when current is over from reference value?
When load is apply current flow through the load CT measures the current and send the value of current to the controller and controller display on the LCD.
As load is increase the value of current also increase and vice versa.
When current increases above the reference value controller observe it and operate the relay then load is cutoff from the generator hence generator is relax and overload display on LCD.
Frequency counter (Opto-coupler)
Optocoupler is a device that use a short optical transmission path to transfer an electronic signal between elements of a circuit, typically a transmitter and a receiver, while keeping them electrically isolated since the electrical signal is converted to a light beam, transferred, then converted back to an electrical signal, there is no need for electrical connection between the source and destination circuits.
Why optocoupler is used?
There are two purposes of using optocoupler
- Protect the circuit from the Main supply of the generator.
- Frequency counting of the generator.
LM-35 is used as a temperature sensor in transmitting unit. It gives the analogue output in terms of varying voltage as the temperature changes.
What will be happen when temperature is over from reference value?
When Body temperature of generator increase above the reference value controller observe it and operate the relay then load is cutoff from the generator ,so generator is relax and over temperature display on LCD.