Power Theft Detection via PLC By, Shashanka B (1RV08EE047) Ravi S Gokavi (1RV08EE041) Chandrashekar C (1RV07EE016)
POWER THEFT Electrical power by altering, slowing, resetting, swapping, or disconnecting an electric meter. Theft also may occur by rewiring circuits to avoid an electric meter, or by tapping into another customer’s electrical lines. The fraudster might use devices to program the theft of power only during certain periods of the day or week. A fraudster may rewire their property to illegally use power from cheaper sources of power, or from meters that are billed at lower rates. To minimize power theft PLC’s can be installed.
PLC (Programmable logic controller) It is a digital computer used for automation of electromechanical process. The PLC’s are designed for multiple input and multiple output. Program to control machine operation are typically stored in non volatile memory. It is an example of a hard real time system since output results must be produced in response to input conditions within bounded time.
Programming of PLC Early PLC’s were programmed by using specific purpose programming terminals. The programs were stored in cassette tape cartridges. Facilities of printing and documentation were very minimal due to the lack of memory. The very old PLC used non-volatile magnetic core memory.
Continued….. Recent PLC’s are programmed using application softwares on personal computers. Computer is connected to PLC through RS-232, RS-485 or RS-422. The software provides the facilities of debugging and troubleshooting the PLC software. Modern PLC’s use EEPROM or EPROM as a memory.
PLC features The main difference from other is that PLC’s are armored for severe conditions and have the facilities for extensive I/O arrangements. It can be connected to sensors, actuators. They also read limit switches and analog process variables. They can operate electrical motors, pneumatic or hydraulic cylinders, magnetic relays etc.
PLC INSTALLATIONPower meters with PLC modules will be installed near the top of the power polls.Meters installed in high places will send data of the used amount to each household through power lines.Homeowners can then check the amount used on the displays installed in each house.This means that the measurement function and the display function of the meters will be separated.Power theft is prevented by installing HD-PLC-mounted power meters on a high position on power polls, while the amount of power used in each household can still be checked.
Each power meter is connected to an optical fiber network, and information of the amount used by each household is sent to the power companies.If the power companies find that a payment is delinquent, they can remotely stop the power supply by controlling the meters through the optical fiber network.The waste of power can also be reduced, another big advantage.Furthermore, wide spread use of the power meters with HD- PLC modules is expected to reduce regional disparities in information, or the ‘digital divide’.
Methods Of Illegal Electricity UsageUsing the mechanical objects: A subscriber can use some mechanical objects to prevent the revolutionof a meter, so that disk speed is reduced and the recorded energy is alsoreduced.Using a fixed magnet: A subscriber can use a fixed magnet to change the electromagnetic fieldof the current coils. As is well known , the recorded energy proportional toelectromagnetic field.Using the external phase before meter terminals: This method gives subscribers free energy without any record.Switching the energy cables at the meter connector box: In this way ,the current does not pass through the current coil of themeter, so the meter does not record the energy consumption.Although all of the methods explained above may be valid for electromechanicalmeters, only the last two methods are valid for digital meters.
The components involved in PLC are, 1. Power Line Carrier Unit which provides signal transmission and reception. 2. There is a Coupler used for “clamping” around a live wire thus injecting the communication signals into the power line. 3. PLC modem
The monitoring system mainly has the following functions1. Remote meter-reading2. Data acquisition3. Thread PLC transmissions are synchronized to the zero crossing point of the AC power line. It should be transmitted as close to the zerocrossing point i.e. within 200 μs. Square wave with amax Delay of 100 μs from the zero crossing point Themaximum delay between signal envelope input and120KHz output bursts is 50 μs. Therefore, it should bearranged that outputs to the within 50 μs.
CODE TRANSMISSION A Binary 1 is represented by a 1 ms burst of 120 KHz. The zero crossing point and a Binary 0 by the absence of 120 KHz. Therefore only the 1 ms "envelope" need be applied to their inputs. These 1 millisecond bursts should actually be transmitted three times to coincide with the zero crossing points of all three phases in a three phase distribution system.
DEFINITION ON AMRAMR(AUTOMATIC REMOTE READING) Automates the process of measurement through digital communication techniques. Bring “intelligence” into the revenue cycle and manage it. The revenue cycle includes metering, billing operating, customer and the services.
ADVANTAGES1. Smart automated process instead of manual work.2. Accurate information from the network load to optimise maintenance and investments.3. Customized rates and billing dates.4. Streamlined high bill investigations.5. Detection of tampering of Meters.6. Accurate measurement of transmission losses.7. Better network performance and cost efficiency.8. Demand and distribution management.9. More intelligence to business planning.10. Better company credibility.
Companies manufacturing PLC’s VIPA art of Automation Unikom-Ug – metering Alstom ABB utility communications ADD group Motorola Delta PLCEtc……