EC&M’s Electrical Calculations Handbook - Chapter 9 docx

... Fig. 9- 1 2 on p. 278. A sample calculation using this table is shown in Fig. 9- 1 3 on p. 2 79. Transformers 273 Figure 9- 9 The transformer output voltage can be adjusted by switching to dif- ferent ... coil. 272 260 Figure 9- 1 0 Table replicating part of NEC Table 45 0-3 (a), overcurrent protec- tion of transformers over 600 V. 274 Figure 9- 1 2 Table replicating part of NEC Ta...

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... Selection 170 Chapter 5. Short-Circuit Calculations 1 79 Sources of Short-Circuit Current 182 The Ability of the Electrical Utility System to Produce Short-Circuit Current 183 Short-Circuit Contributions ... On-Site Generators 184 Short-Circuit Contributions of Motors 185 Let-Through Values of Transformers 187 Let-Through Values of Reactors 188 Let-Through Power Values of Cables 1 89...

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... Volt, 3-phase 4-wire wye Note 5 460 Volt, 3-phase 3-wire delta Note 4 600/347 Volt, 3-phase, 4-wire wye 2400 Volt, 3-phase, 3-wire delta 2400 Coltm 3-phase, 4-wire wye 4160/2400 Volt, 3-phase, 4-wire ... = (180) 2 + (104) 2 Minus Phase b voltage - (120 120 ° = - 120 -6 0 ° ) = -( -1 20 COS 60 -j 120 SIN 60) = -[ (-1 20)(5) -j (120)(.866)] = -[ -6 0 +j 103 .92 ] Phase...

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... VECTOR 180 - 37.4° AMP 20 .9 -1 6.6 +j 12.7 (-X, +J) (+X, +J) (-X, -J) (+X, -J) Step 3. Draw the resultant vector. +X +J -J (-X, -J) NEW RESULTANT VECTOR -1 6.6 +j 12.7 180 ° - 37.4 ° AMP 20 .9 (-X, ... voltages is Institute of Electrical and Electronics Engineers (IEEE) Standard 51 9- 1 99 2 (sometimes listed as IEEE 51 9- 1 99 3 because it was completed in 199 2 and i...

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... DEG. F 60 75 90 2 1-2 5 7 0-7 7 1.08 1.05 1.04 2 6-3 0 7 8-8 6 1 1 1 3 1-3 5 8 7 -9 5 0 .91 0 .94 0 .96 3 6-4 0 9 6-1 04 0.82 0.88 0 .91 4 1-4 5 10 5-1 13 0.71 0.82 0.87 4 6-5 0 11 4-1 22 0.58 0.75 0.82 5 1-5 5 12 3-1 31 0.41 0.67 ... REMARKS 31 0-1 6 OR 31 0-1 7 31 0-1 6 OR 31 0-1 7 UNDERGROUND FEEDER CABLE 31 0-1 6 OR 31 0-1 7 MOISTURE AND HEAT R...

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... electrical systems against damage during short-circuit conditions is required by the National Electrical Code (Secs. 11 0 -9 and 11 0-1 0). Short-Circuit Calculations 181 For example, in a three-phase ... 30-MVA generator 3. The 5000-hp motor 4. The motors connected to the 480-V bus Short-Circuit Calculations 191 Figure 5-1 Electrical power system one-line drawing for short-ci...

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... 50 Generator Sizing Calculations 199 Figure 6-1 Solve for generator site rating given load, temperature, and altitude. tection devices requires unique methodologies. The genera- tor kilowatt rating ... motor is still running. For 196 Chapter Six tem voltage at the terminals of the motor being started and around 90 percent of the normal system voltage at the genera- tor switchgear bus...

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... such as a 460-volt (V), three-phase, three-wire delta system, an arc- ing fault that repeatedly restrikes can cause voltage “jack- ing” of up to six times the normal system phase-to-neutral voltage. ... enough equipment-grounding conductors, as shown in Fig. 7-4 . Since system grounding is done at the service-disconnect- ing means, the equipment-grounding conductor and the neu- tral (“groun...

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... necessary to use the point-by-point method. The Point-by-Point Method How to make point-by-point calculations Later in this chapter, lighting calculations within areas hav- ing reflective surfaces, ... footcandles from the second luminaire. Sample point-by-point lighting calculations Refer to Fig. 8-1 for sample point-by-point lighting calcula- tions for both the nadir point and a po...

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... 5. 59 G 5.6 5 .94 5 6. 29 H 6.3 6. 695 7. 09 J 7.1 7.545 7 .99 K 8 8. 495 8 .99 L 9 9. 495 9. 99 M 10 10. 595 11. 19 N 11.2 11.845 12. 49 P 12.5 13.245 13 .99 R 14 14 .99 5 15 .99 S 16 16 .99 5 17 .99 T 18 18 .99 5 19. 99 U ... compensated for, Motors 2 89 300 Figure 1 0-8 : Continuous-duty motors driving a continu- ous-duty load (pp. 300 and 301) Figure 1 0 -9 : Continuous...

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