Hardware Implementation of Digital Over current relay on Arduino

Date : Sep 2016 - Dec 2016

Over current protection:  A relay that operates or picks up when it’s current exceeds a predetermined value (setting value) is called Over Current Relay.  Over current protection protects electrical power systems against excessive currents which are caused by short circuits, ground faults, etc. Over current relays can be used to protect practically any power system elements, i.e. transmission lines, transformers, generators, or motors.  For feeder protection, there would be more than one over current relay to protect different sections of the feeder. These over current relays need to coordinate with each other such that the relay nearest fault operates first. Use time, current and a combination of both time and current are three ways to discriminate adjacent over current relays. Over Current Relay gives Protection against:  Over current includes short‑circuit protection.  Short circuits can be protected.  Phase faults.  Earth faults.  Winding faults. Short‑circuit currents are generally several times (5 to 20) full load current. Hence fast fault clearance is always desirable on short circuits. Motor Protection:  Used against overloads and short‑circuits in stator windings of motor.  Inverse time and instantaneous over current phase and ground  Over current relays used for motors above 1000kW. Transformer Protection:  used only when the cost of over current relays are not justified  Extensively also at power‑transformer locations for external‑fault back‑up protection. Line Protection:  On some sub transmission lines where the cost of distance relaying cannot be justified.  primary ground‑fault protection on most transmission lines where distance relays are used for phase faults Distribution Protection:  Over Current relaying is very well suited to distribution system protection for the following reasons:  It is basically simple and inexpensive Very often the relays do not need to be directional and hence no PT supply is requi