How does a microprocessor relay work?
Microprocessor-based relays, also called digital relays, typically consist of an ac signal data acquisition system, a microprocessor, memory components containing relay algorithms, contact inputs to control the relay, and contact outputs to control other equipment.
What is the working principle of relay?
Relay works on the principle of electromagnetic induction. When the electromagnet is applied with some current it induces a magnetic field around it.
How do protection relays work?
Protective relay work as a sensing device, it senses the fault, then known its position and finally, it gives the tripping command to the circuit breaker. Such relays sense the fault and send a signal to the proper circuit breaker to trip and clear the fault.
What is relay and its application?
Relays are used for isolating a low voltage circuit from high voltage circuit. They are used for controlling multiple circuits. They are also used as automatic change over. Microprocessors use relays to control a heavy electrical load. Overload relays are used for protection of motor from overload & electrical failure.
What is the advantage of microprocessor-based relay?
The main advantage of this relay is that it is programmable. The program can handle the online calculations and make the decision accordingly. Another important advantage of the microprocessor-based relay is that a microprocessor unit can perform the retransmission operation of several systems.
What is microprocessor-based distance relay?
The characteristic of a distance relay is realised by comparing voltage and current at the relay location. The ratio of voltage (V) to current (I) gives the impedance of the line section between the relay location and the fault point.
Are relays AC or DC?
General Purpose Relays are electromechanical switches, usually operated by a magnetic coil. General purpose relays operate with AC or DC current, at common voltages such as 12V, 24V, 48V, 120V and 230V, and they can control currents ranging from 2A-30A.
What is the disadvantage of microprocessor based relay?
The electromechanical relays suffer from several drawbacks such as high burden on instrument transformer, high operating time, contact problem etc. The static relays also suffer from a number of disadvantages such as inflexibility, inadaptability to changing system conditions and complexity.
How does a microprocessor-based relay work?
Figure shows the block diagram of the microprocessor-based relay. The output of the CT line is given to the input receiver block where the signal is processed. Signal processing includes overvoltage protector, rectifier, smoothing filters, auxiliary CT, etc., depending on the requirements. This signal is an analog signal.
How inverse over current relay is implemented in microprocessor?
Inverse over current relay is implemented using 8 bit 8085 microprocessor. Integrated type and look up table based time-current characteristics is realized using function generator program of microprocessor [1]. Field programmable gate array based on over current relay is developed for 360 km long transmission line.
What is the logic of relay logic?
Relay logic is very important to understand the microprocessor-based relay. The relay can be ON or OFF, that is, it has two stable states. Similarly, the output of a logic function is activated, that is, high or deactivated, that is, low. The three basic logical functions are: AND, OR and NOT functions.
Can overcurrent relays be used for TK-85 programming?
A proposed scheme of overcurrent relays dealing with programming of the single-board microcomputer TK-85, built by NEC around Intel’s 8-bit 8085 microprocessor, is described. Experimental results with better relay characteristic performances and high flexibility for implementing the desired value of n, including noninteger values, are obtained.