Factory Test of Power Transformer ( I )
1, Routine (Factory) Test Project
The factory test of power transformer can be divided into three types: routine (factory) test, type test and special test. Routine test is a test project for each transformer factory should be carried out, usually referred to as factory test; type test is to test items in one type of product chouce 1~2 transformer to carry out; the special test is made by the user, with the consent of the pilot project and in consultation with the manufacturer.
The transformer windings are checked according to the highest operating voltage Um and the corresponding insulation level. The following is the national standard GB1094.3 – 2003 insulation test item stipulated in the third parts of the power transformer: insulation level, insulation test and external insulation air gap.
(1) measuring the DC resistance of windings: measurement on all the lead end of the split.
(2) variable ratio measurement: measurement at all split positions.
(3) connection test: test at the rated location.
(4) measurement of insulation resistance, absorption ratio and polarization index: 220kV and above transformers only measure the polarization index.
(5) test of tanδ and capacitance of windings: 35kV and above transformers should be measured by tanδ.
(6) casing tanδ and capacitance measurement: 66kV and above capacitive bushing should be tested for tanδ and capacitance
(7) transformer oil test: oil analysis, insulation strength, tanδ, chromatographic analysis and other items. 750kV and above transformer also need to carry out particle size test in oil. Furthermore, the analysis of oil and the chromatographic analysis of oil should be repeated during the whole process.
(8) measurement of no-load loss and no-load current: test under rated voltage connection.
(9) measurement of load loss and short circuit impedance: test under rated voltage connection.
(10) partial discharge test: discharge quantity inaction assessment, only as a reference for high voltage test.