A low cost microprocessor based relay for ground fault protection

This paper presents the design and implementation of a microcontroller based multi-functional relay that can protect the equipment against over-current, over-voltage & under voltage. Provision for settings of over voltage, over current and under voltage limits is provided. Simulations are carried out using proteus eight (SP4) platforms and hardware prototype with ATMega328 as core controller is built to validate the operation of the microcontroller as multifunctional numerical relay. Index Terms--Arduino Uno board, ATMega328, faults, micro controller, over current relay, proteus 8 professional). I. INTRODUCTIONhe reliability and security electrical supply is an important factor in modern society. However increasing complexity of power systems makes it difficult for protection operation to achieve these objectives. Nevertheless, numerical relays are able to improve the protection operation significantly. The relays are capable of performing complex processing faster and with higher accuracy [1].Protection relay is a device which by means of measuring power system quantities (currents and voltages) and processing them through its internal logic, has the capacity to control the operation of a circuit breaker. The internal logic allows the relay to initiate a tripping sequence when anomalous conditions arise within the power system. With regard to their construction three types of relays can be distinguished: electromechanical, static and digital. In electromechanical relays, the actuating force is created by electromagnetic interaction. Static relays are based on analogue electronic components such as diodes, transistors, capacitors, etc. whereas numerical relays have their logic implemented in software and microprocessor technology. Some relay designs combine the static and digital technology. This paper concentrates on the analysis of digital relays. A digital relay consists of the following main parts: microcontroller, analogue input system, digital output system and independent power supply [2]. Figure 1 presents a simplified block diagram of a digital relay. The National Electrical Code defines over current as any current in excess Gandi ramarao ,Sateesh K Telagamsetti, PG students, V S Kale, Associate Professor are with the

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“…"+/-12V supply is designed for amplifier LMP8601". A single 5v dc power source is necessary to run the electronics on the board [10].…”

Section: Regulated Power Supplymentioning

confidence: 99%