IEC 60076-15:2008 pdf free download Power transformers – Part 15: Gas-filled power transformers
13.2Gas tightness
IEC 62271-1 gives general rules to the gas tightness of high-voltage switchgears.This rulecan be applicable to the gas-filled transformers.
The tightness characteristic shall be consistent with a minimum maintenance and inspectionphilosophy.The tightness for gas is specified by the relative leakage rate Frel-
For sulfur hexafluoride-filled transformers,the relative leakage rate of SF。 shall not exceed0,5 percent per year. For transformers filled with the mixture,consisting of SF。 and othergases, the relative leakage rate of the mixture shall not exceed 0,5 percent per year.
14General requirements for tests
New transformers shall be subjected to tests as specified below.
Tests shall be made at any ambient temperature between 10 °C and 40 °C.For water cooledtransformer, tests shall be made at any water temperature not exceeding 25 °C.
Tests shall be made at the manufacturer’s works，unless otherwise agreed between thesupplier and the purchaser.
All external components and fittings that are likely to affect the performance of thetransformer during the test shall be in place.
Tapped windings shall be connected on their principal tapping, unless the relevant test clauserequires otherwise or unless the supplier and the purchaser agree otherwise.
The test basis for all characteristics other than insulation is the rated condition，unless thetest clause states otherwise. Dielectric tests shall be performed in guaranteed minimum gaspressure.
All measuring systems used for the tests shall have certified，traceable accuracy and besubjected to periodic calibration,according to the rules of 7.6 of iso 9001.
NOTE Specific requirements on the accuracy and verification of the measuring systems are under consideration(see lEC 60076-8).
lf test methods are not prescribed in this standard,or if tests other than those listed in thisstandard are specified in the contract, such test methods are subjected to agreement betweenthe supplier and the purchaser.
15 Measurement of winding resistance (routine test)
The test described in lEC 60076-1 applies.
16 Measurement of voltage ratio and check of phase displacement (routine test)
The test described in IEC 60076-1 applies.
17 Measurement of short-circuit impedance and load loss (routine test)
The test described in IEC 60076-1 applies.
The reference temperature of the short-circuit impedance and load loss shall be
– 75 °C for an insulation system temperature of 1 05 °C;
– average winding temperature-rise plus 20 °C for other average winding temperature-rise.
NOTE Reference temperature with an insulation system of class 200 or above shall be subjected to agreement between the supplier and the purchaser.
When a transformer has windings of different insulation system temperatures, the reference temperature relating to the winding having the higher insulation system temperature shall be used.
18 Measurement of no-load loss and current (routine test)
The test described in IEC 60076-1 applies.
19 Tests on on-load tap-changers (routine test)
The test described in IEC 60076-1 applies.
20 Measurement of zero-sequence impedance(s) on three-phase transformers (special test)
The test described in IEC 60076-1 applies.
21 Measurement of the harmonics of the no-load current (special test)
The test described in IEC 60076-1 applies.
22 Separate-source AC withstand voltage test (routine test)
The test described in IEC 60076-3 applies.
23 Short-duration induced AC voltage test (ACSD) (routine or special test)
The test described in IEC 60076-3 applies. Routine or special test is in accordance with IEC 60076-3.
IEC 60076-15:2008 pdf free download
