The relay whose operation depends on the phase difference of two or more electrical quantities is known as the differential protection relay. This video outlines the basic principles behind differential protection and is a sample of the full 2. Bus protection is an application that demands many sets of cts be connected to the relays. The relay which is used to checks the difference between the output and input currents for power system current in known as differential relay.
The principles of differential protection you must. It is also an application that demands the relay be able to operate with unequal ct. Applying sel differential relays introduction to transformer differential protection explain challenges of transformer differential protection understand need for tap, phase, and zerosequence compensation and how they work. Principle and operation of differential relay my tech info. Protection relays differential relays high impedance differential relay highimpedance differential relays are typically used for bus protection. Learn the basics of differential protection of transformers. Siprotec protection relays figure 1 shows a simple differential protection scheme, also known as a merzprice scheme. In this type of protection the electrical quantities entering and leaving the protected zone or area are compared by current transformers c. Operating time, sensitivity, dependability and security requirements are examined for typical applications. In the differential relay scheme circuit, there are two currents come from two parts of an electrical power circuit. Principles of differential relaying current balance high impedance. Current differential line protection setting consideration.
It works on the principle of comparison between the phase angle and the magnitude of the same electrical quantities. The differential relay is one that operates when there is a difference between two or more similar electrical quantities exceeds a predetermined value. The principles of differential protection you must understand on photo. Principle and operation of differential relay what is differential relays. Operational manual if the relay setup is carried out with use of pc, service settings is also available. Fault current through rscould lead to dangerous overvoltages voltage limiters are required. If the net difference equal zero, it means no fault exist. In this simple scheme, we can assume that under normal operating conditions, the current entering into the piece of equipment under protection is equal or in the case of a transformer, proportional to its exiting current. Easy method for testing transformer differential relays conference paper pdf available september 2009 with 14,350 reads how we measure reads. This paper summarizes the operating principle of a high impedance protection unit, its relay.
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