What are the test items of current transformer and potential transformer, and what are their standards?
Dielectric loss tangent test. Dielectric loss tangent test CT requirements: 1) the measurement of dielectric loss of primary windings and capacitance value, is then measured using dielectric loss measurement instrument; end screen of dielectric loss and capacitance value of the test voltage is 2000V,, reverse connection measurement using dielectric loss meter, current transformer for high voltage terminal shielding line; 2) dielectric loss value comparison should not change significantly with the calendar year;3) of oil immersed: 500kV: transfer of not more than 0.5%; pre test is less than 0.7%; 220kV: transfer of not more than 0.6%; pre test is less than 0.8%; 110kV: transfer of not more than 0.8%; pre is not greater than 1%; 35kV pre test according to 110kV standard, but the transfer is not greater than 2.5%; dielectric loss value should be less than 2%. 4) added to the standard: filling grease transfer silicone oil dry type current transformer is not greater than 0.5%
Dielectric loss tangent test CT measurement points: 1) the main insulation test voltage is TG Delta 10kV, delta TG end screen of the test voltage is 2kV. 2) oil paper capacitor TG delta is generally not the temperature conversion, when the TG value or a test value have more obvious growth and factory value, should be comprehensive analysis of TG delta with temperature and voltage, when the temperature changes or TG delta test voltage from 10kV up to Tg, more than 8 increment 0.3% (0.2% over, capacity 0.5%), should not continue to run.
Insulation resistance test:Insulation resistance test requirements: use 2500V megohmmeter, winding insulation resistance and the initial value and historical value comparison should not change significantly, and not less than 1000 mu Omega, end screen of insulation resistance of not less than 1000 m, if the end screen of the insulation resistance of less than 1000 M, the tan should be measured.
