JIS C 4306:2013

Introduction1 Scope2 Normative references3 Definitions4 Normal service conditions5 Unusual service conditions6 Classification by thermal class7 Ratings 7.1 Classification by rated power 7.2 Rated voltages 7.3 Tapping voltages 7.4 Rated power factor8 Performances 8.1 No-load current 8.2 No-load loss 8.3 Transformation ratio 8.4 Short-circuit impedance 8.5 Balance of single-phase 3-wire system 8.6 Voltage regulation 8.7 Efficiency 8.8 Limit of temperature rise 8.9 Dielectric strength 8.9.1 Applied potential withstand voltage 8.9.2 Induced withstand voltage 8.9.3 Lightning impulse withstand voltage 8.10 Partial discharge 8.11 Noise 8.12 Ability to withstand short circuit 8.12.1 Thermal ability 8.12.2 Mechanical ability 8.13 Variation in voltage and frequency 8.14 Resistance to cracking 8.15 Resistance to damp heat 8.16 Flame retardance 8.17 Tolerance9 Construction 9.1 Construction in general 9.2 Tap change-over terminals 9.3 Earth terminal 9.4 Connection of transformer 9.4.1 Single-phase transformer 9.4.2 Three-phase transformer 9.5 Terminal mark, polarity and phase displacement 9.5.1 For single-phase transformer 9.5.2 For three-phase transformer10 Tests 10.1 General matters relating to routine tests, type tests and special tests 10.1.1 Routine tests 10.1.2 Type tests 10.1.3 Special tests 10.2 Measurement of winding resistance 10.3 No-load current and no-load loss tests 10.4 Transformation ratio test, polarity test and phase displacement test 10.5 Load loss and short-circuit impedance tests 10.6 Test for balance of single-phase 3-wire system 10.7 Voltage regulation 10.8 Efficiency 10.9 Temperature rise method 10.9.1 Loading methods 10.9.2 Thermal equilibrium state 10.9.3 Methods for measurement and calculation of transformer temperature 10.9.4 Determination of reference ambient temperature 10.9.5 Temperature rise 10.10 Dielectric withstand voltage tests 10.10.1 Applied potential withstand voltage test 10.10.2 Induced withstand voltage test 10.10.3 Lightning impulse withstand voltage test 10.10.4 Repetitive discharge test 10.11 Partial discharge test 10.12 Noise test 10.12.1 Test method 10.12.2 Background noise 10.12.3 Measuring method of transformer noise level 10.12.4 Calculation method of transformer noise level 10.12.5 Correction for background noise 10.13 Test for ability to withstand short-circuit 10.13.1 General 10.13.2 Thermal ability 10.13.3 Mechanical ability 10.14 Test for resistance to cracking 10.14.1 Methods for heating and cooling in the test 10.14.2 Test method 10.15 Test for resistance to damp heat 10.15.1 Humidifying method in the test 10.15.2 Test method 10.16 Flame retardance test 10.17 Construction test11 Designation of product12 Marking

Defines transformers with a rated power not exceeding 500 kVA and a rated frequency of 50 Hz or 60 Hz in the category of 6 kV single-phase or three-phase indoor self-cooled encapsulated-winding transformers used for the purpose of general power distribution.

2013 [20/05/2013]2005(R2010) [01/10/2010]2005 [20/04/2005]99 [20/11/1999]91 [01/06/1992]