Line to-line sustained short-circuit test
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This document provides instructions for performing a line-to-line sustained short-circuit test on synchronous machines to determine the negative sequence reactance (X2) and resistance (R2). The test involves short-circuiting any two line terminals and measuring quantities like short-circuit current, voltage, and active power at various excitation levels up to 0.3 times the rated current. Precautions are outlined to prevent overheating or excessive vibration during the test. Deviations from nominal test values require a nonconformity report. The document is the property of PNG Power and not to be shared with third parties.
Line to-line sustained short-circuit test
- 1. Line to line sustained short circuit test Table of Content: 1 Objective........................................................................................................ 2 Scope............................................................................................................. 3 Referenced Documents................................................................................. 4 Definitions and abbreviations........................................................................ 5 Line to line sustained short-circuit test.......................................................... 5.1 Connection (see diagram) ...................................................................... 5.2 Machine condition................................................................................... 5.3 Measured quantities .............................................................................. 5.4 Evaluation .............................................................................................. 5.5 Problems ................................................................................................ 6 Proceeding in case of deviations.......................................................................... 7 Copyright ............................................................................................................... 1 Objective Determination of negative sequence reactance X2 and negative sequence resistance R2. 2 Scope All synchronous machines of all kinds, tested in the work shop or at site. 3 Referenced Documents IEC 34-4, 48-49 IEEE 115, 10.5.4 Method 3 EN 60034-4 4 Definitions and Abbreviations None 5 Line to line sustained short-circuit test 5.1 Connection (see diagram) Short-circuit any two line terminals by inserting ampere meter and wattmeter (current circuit) Note: It is recommendable to perform this test immediately after the three-phase sustained short-circuit test, removing the short-circuit between two line terminals. Connect voltmeter between open line terminal and one of the short-circuited terminals 5.2 Machine condition Machine is driven at rated speed by turbine or motor resp. Note: When a prime mover is not available, this test can also be performed by retardation 8/24/2005 7:36 a8/p8 Page 1 of 3
- 2. method, measuring when the decelerating machine passes through nominal speed. Set excitation level to several values of the short-circuit current up to max. 0,3 In and take readings. 5.3 Measured quantities Short-circuit current (I) and field current (If) voltage between open line terminal and short circuited terminals (U) active power of short-circuit (P) Note: Measurement of reactive power (Q) is not considered necessary. A special VAr- meter would be required for measuring Q. 5.4 Evaluation 5.5 Problems - danger of overheating solid parts should higher current levels than 0,3 In be stipulated in the contract restrict test duration to time required for reading of instruments - danger of excessive vibration for non-salient pole machines limit armature current in any case to 0,5 In 6 Proceeding in case of deviations Any nominal value, minimum value, maximum value, tolerance etc given in an instruction intended to serve for quality control purposes only. In the case of deviations, a nonconformity report has to be written according to PNG Power Standard. 8/24/2005 7:36 a8/p8 Page 2 of 3
- 3. 7 Χοπψριγητ This Document is properly of PNG Power internal use only and must neither be copied. Neither is it to be handed over nor in other way communicated to a third party. Infringement will lead to prosecution. 8/24/2005 7:36 a8/p8 Page 3 of 3