Fig 9 THD Make Watt PF Ct(%) 1 3.7 183 0.45 2 9.4 154 0.50 3 10.7 166 0.50 4 29.7 35 0.94 5 22.4 35 0.93 6 14.8 6 0.96 Table 5 3.4 Quality Standard for Utility Supply A very useful standard for practical applications is - EN 50160:2000 Voltage “BS characteristics of electricity supplied by public distribution systems”. The limits and tolerances of important phenomena that can occur from supply side are summarized in 6. Supply voltage Acceptable Measurement Monitorin Acceptance phenomenon limits Interval g Period Percentage 49.5Hz to 50.5Hz 95% Grid Frequency 10 S 1 Week 47Hz to 52Hz 100% Slow voltage changes 230V 10% 10 min 1 Week 95% Voltage Sags or Dips 10 to 1000 10 ms 1 Year 100% per year (under ( 1 min) 85% of nominal) Short Interruptions 10 to 100 times 10 ms 1 Year 100% per year (under ( 3 min) 1% of nominal) Mostly 2% but Voltage unbalance 10 min 1 Week 95% occasionally 3% 8% Total Harmonic Voltages 10 min 1 Week 95% Harmonic Distortion (THD) Table 6
Fig 9 Make Watt THD Ct(%) PF 1 3.7 183 0.45 2 9.4 154 0.50 3 10.7 166 0.50 4 29.7 35 0.94 5 22.4 35 0.93 6 14.8 6 0.96 Table 5 3.4 Quality Standard for Utility Supply A very useful standard for practical applications is “BS - EN 50160:2000 Voltage characteristics of electricity supplied by public distribution systems”. The limits and tolerances of important phenomena that can occur from supply side are summarized in 6. Supply voltage phenomenon Acceptable limits Measurement Interval Monitorin g Period Acceptance Percentage Grid Frequency 49.5Hz to 50.5Hz 47Hz to 52Hz 10 S 1 Week 95% 100% Slow voltage changes 230V 10% 10 min 1 Week 95% Voltage Sags or Dips ( 1 min) 10 to 1000 per year (under 85% of nominal) 10 ms 1 Year 100% Short Interruptions ( 3 min) 10 to 100 times per year (under 1% of nominal) 10 ms 1 Year 100% Voltage unbalance Mostly 2% but occasionally 3% 10 min 1 Week 95% Harmonic Voltages 8% Total Harmonic Distortion (THD) 10 min 1 Week 95% Table 6
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