With the growth of renewable energy sources and the general expansion of the power transmission network, more and more underground and undersea power cables are being installed. Testing these cables has, in the past, been costly and difficult, but this...

Past methods of testing power swing and out-of-step conditions have often involved a brute force approach of applying voltages and currents to simulate impudences seen by the relay. 

The transformer turns ratio (TTR) test is very important; it confirms that the transformer has the correct ratio of primary turns to secondary turns. Using this test correctly can help to identify shorted turns, open windings, incorrect winding connections...