What are the types of differential protection?
There are mainly two types of differential relay depending upon the principle of operation.
- Current Balance Differential Relay.
- Voltage Balance Differential Relay.
What is cable differential protection?
In this cable/line design, cable differential protection provides reliable discrimination between faults in the cables and on overhead lines. They exchange current phasor information to determine if a fault is on the cable (In-Zone) or on the overhead line (Out-of-Zone).
What are disadvantages of differential protection?
The differential scheme described suffers from the following drawbacks: Unmatched characteristics of CTs. Ratio change as a result of tapping. Magnetizing inrush current.
Which CT is used for differential protection?
The PS class CTs are used for differential protection. The differential protection is also called the zone or unit protection.
How a differential protection scheme operates?
Definition: The relay whose operation depends on the phase difference of two or more electrical quantities is known as the differential protection relay. It works on the principle of comparison between the phase angle and the magnitude of the same electrical quantities.
What is busbar differential protection?
The scheme of busbar protection, involves, Kirchoff’s current law, which states that, total current entering an electrical node is exactly equal to total current leaving the node. Hence, total current entering into a bus section is equal to total current leaving the bus section.
What is partial differential protection?
Partial-differential Protection is a modified version of current differential protection . It is suitable for the only double ended substation which means two incoming circuit breakers with tie circuit breaker.
How is differential protection work in a transformer?
Transformer Differential Protection Scheme works by using two separate quantities calculated from the primary current (IW1C) and secondary current (IW2C). SEL787 and SEL 387/587 Transformer differential relay is used for this discussion. Other similar relays use similar concepts through the actual terminology could be different.
What is differential protective relay?
Differential protection relay is the one that operates depending upon the difference between two or more similar electrical quantities exceeds a predetermined value. It is very commonly used relay for protecting transformers and generators from localised faults.
What is differential ground fault protection?
Modified Differential Ground Fault Protection Systems. A system intended to provide protection of equipment from damaging line-to-ground fault currents by operating to cause a disconnecting means to open all ungrounded conductors of the faulted circuit.