What is a microprocessor-based relay?
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 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 are the types of overcurrent relays?
An overcurrent relay is a type of protective relay which operates when the load current exceeds a pickup value. It is of two types: instantaneous over current (IOC) relay and definite time overcurrent (DTOC) relay.
What are the principles of over current relays?
Construction and working principle of instantaneous over current relay is quite simple. Here generally a magnetic core is wound by a current coil. A piece of iron is so fitted by hinge support and restraining spring in the relay, that when there is not sufficient current in the coil, the NO contacts remain open.
What are the advantages of microprocessor relays IEDs compared to electromechanical relays?
Today’s IEDs are much more reliable than legacy electromechanical relays, and they perform a better job of ensuring power system stability by clearing and isolating faulted components much faster, while providing power system real-time information.
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.
What are the main advantages of microprocessor based relay compared to electro mechanical relay?
Microprocessor-based relays offer many advantages over schemes using discrete components. The overall scheme takes up less panel space. The number of components is greatly reduced. The design and wiring is simpler and less costly to implement.
What is meant by overcurrent relay?
Definition: The overcurrent relay is defined as the relay, which operates only when the value of the current is greater than the relay setting time. It protects the equipment of the power system from the fault current.
What are the types of overcurrent?
Types of Overcurrent. The three major categories or types of overcurrent are overload, short-circuit, and ground-fault.
What do overcurrent relays protect?
Overcurrent protection protects electrical power systems against excessive currents which are caused by short circuits, ground faults, etc. Overcurrent relays can be used to protect practically any power system elements, i.e. transmission lines, transformers, generators, or motors.
What are the three common types of over current relays?
Based on the relay operating characteristics, overcurrent relays can be classified into three groups: definite current or instantaneous, definite time, and inverse time.