What is the purpose of an out of step relay?
The principal application for the out-of-step tripping relay (Fig. 10) is to obtain tripping at desired locations during a loss of synchronism condition.
What is stable power swing?
Stable Power Swing: a power swing is considered stable if the generators do not slip poles and the system reaches a new state of equilibrium, i.e. an acceptable operating condition.
What is out of step protection?
Out-of-step protection functions detect stable power swings and out-of-step conditions by using the fact that the voltage/current variation during a power swing is gradual while it is virtually a step change during a fault.
What is an out of step generator?
Out-of-Step or Loss of Synchronism is a condition where a generator experiences a large increase in the angular difference of the Electro Motive Force (EMF) with other generators or portions of a system to which it is connected, usually following a major power system disturbance.
What are zones of protection?
“Zones of protection” is one strategy that can be used to provide the level of security demanded today. Protective relay engineers keep utility grids and equipment safe from faults and system unbalances by dividing the grid into zones, each with a unique protection scheme. Overlapping zones provide backup protection.
What is Idmt relay?
IDMT relay is inverse definite minimum time relay. It is one in which Time of operation is inversely proportional to magnitude of fault current near pickup value and becomes substantially constant slightly above the pickup value of the Relay.
What is RX diagram?
The R-X graph shows an apparent impedance which has a complex relationship to the actual Rf depending on the power system conditions. The fault position vs. true Rf graph can remove all of those effects and show the true performance no matter what the power system conditions are.
What are the types of protection scheme?
Protection Schemes
- Overcurrent Protection Scheme.
- Differential Protection Scheme.
- Distance Protection Scheme.
- Directional Protection Scheme.
What is meant by 3 zone protection?
The protective zone of the third stage is known as the third zone of protection. The setting of the third zone covers the first line, i.e. the protected line plus the longest second line plus 25% of the third line. The time-delay for the third unit is usually 0.4 s to 1 s.
What is Idmt and IDMT relay?
IDMT means the minimum minimum time spent. As the current increases, the relay requires a minimum time to stop the circuit. idmt meaning: Inverse means “a higher value of the current, less time required for the relay to activate the circuit”.
What is CDG relay?
Type CDG 11. Overcurrent and Earthfault Relay. General description. A non-directional heavily damped induction disc relay which has an adjustable inverse time/current characteristic with a definite minimum time. The relay has a high torque movement combined with low burden and low overshoot.