IN TODAY’S INDUSTRIAL WORKPLACE THE PROLIFERATION OF SOLID STATE DEVICES LIKE LIGHTNING BALLASTS,MOTOR DRIVES AND CONTROLS,COMMUNICATION EQUIPMENT HAS CREATED A MAJOR PROBLEMS.THE NON LINEAR NATURE OF THESE SMPS GENERATE HARMONIC CURRENT THAT CAN CAUSE TRANSFORMER AND SYSTEM NEUTRAL TO OVER HEAT AND DESTROY THEMSELVES.
“K-FACTOR” IS THE WEIGHING OF HARMONIC CURRENT ACCORDING TO THEIR EFFECTS ON TRANSFORMER HEATING.THE HIGHER THE K-FACTOR GREATER THE HARMONICS HEATING EFFECT.
WHEN A NON LINEAR LOAD IS SUPPLIED FROM TRANSFORMER IT IS SOMETIMES NECESSARY TO DERATE THE TRANSFORMER CAPACITY TO AVOID OVERHEATING AND SUBSEQUENT INSULATION FAILURE.
THE PERFORMANCE ANALYSIS OF A TRANSFORMER IN HARMONIC ENVIRONMENT REQUIRES FOLLOWING KNOWLEDGE
- LOAD MIX
- DETAILS OF LOAD CURRENT HARMONIC CONTENT
- TOTAL THD
THE ADDITIONAL HEATING EXPERIENCED BY TRANSFORMER DEPENDS ON THE HARMONIC CURRENT ON THE LOAD CURRENT.K-RATED TRANSFORMERS ARE DESIGNED WITH DIFFERENT DESIGN TECHNIQUES LIKE
- PARALLEL CONDUCTORS,LOW FLUX DENSITIES AND STATIC SHIELD
- DOUBLE THE SIZE OF NEUTRAL TO WITHSTAND THE TRIPLEN HARMONICS
- CLASS ‘H’ INSULATION