IEC Vs NEC Hazardous Area Classification Comparison





















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Transformer Design - IEC Vs ANSI/IEEE

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    TRANSFORMERS DESIGN PARAMETERS IEC ANSI/IEEE For transformers up to 10 MVA, values of rated power roughly follow the R-10 series [3] given in ISO 3 (1997), preferred numbers : (…100, 125, 160, 200, 250, 315, 400, 500, 630, 800, 1000, 1250, etc.) Reference ANSI / NEMA C57 standard for power and distribution transformers, Standard ratings for different cooling methods OA / FA 55 / 650 C, and for standard impedance. Commonly International practice is to use Sealed tank transformers up to 1600 kVA and Conservator type for larger transformers American typical common practice in Petroleum & Chemical (P&C) applications is to use sealed tank transformers up to 15-20 MVA and conservator type for larger transformers. Shall be capable of sustaining a maximum of 105% rated Volts/Hz continuously without damage Shall sustain 110% Volts/Hz at no-load and shall be able to deliver rated power at 110% of the rated secondary vol...
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For Heat Tracing Design - Sample Heat Loss Calculation for 450 MM NB Pipe

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Formula: q = 2∏K x (Tm-Ta) / ln(D2/D1) q = Heat loss per unit length of pipeline (W/mtr.) Tm = Maintenance Temperature (deg. C) Ta = Minimum Ambient Temperature (deg. C) D1 = Diameter of pipe (mtr) D2 = Diameter of pipe including Insulation thickness (mtr) K1 = Thermal Conductivity of Insulation material evaluated at its mean temperature (W/m .deg.K) Sample Calculation: Pipe Size (OD) = 457.2 mm Maintenance Temperature (Tm) = 40 deg. C Min. Ambient Temperature (Ta) = -0.7 deg. C Insulation Material = Mineral Wool Thermal Conductivity of Insulation at mean temp. 65 deg. C (K) = 0.038 W/m. deg. C Insulation Thickness (t) = 45 mm Diameter of Pipe (D1) = OD of Pipe = 457.2 mm Diameter of Pipe including Insulation thickness (D2) = D1+2t = 547.2 mm Putting the above values in heat loss formula, we have Heat loss/mtr of pipeline (q) = 54.08 Watts Heat loss/mtr of pipeline with 10% design Margin = 59.5 Watts Hence to compensate the required hea...
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