AC Power Systems: Single Phase vs Three Phase, Study Guides, Projects, Research of Electrical and Electronics Engineering

Download AC Power Systems: Single Phase vs Three Phase and more Study Guides, Projects, Research Electrical and Electronics Engineering in PDF only on Docsity! Basic Type of AC Power Systems Types Single Phase 120/240 volt, 1 phase, 3 wire Application Any load up to 400 A, then should consider 3 phase. Motors 7.5 HP maximum. Most equipment available 120- 240-Volt. This is the most standard system. Individual unit heaters are limited to about 10 KW max. Three Phase Three Phase 120/208 V, WYE, 3 phase, 4 wire Any application from 200A up, allows motors larger than 7.5 HP and has 120 volts available from all legs to neutral. Must have 208 Volt rated motors and heaters. Easy to balance 120 Volt loads From each phase to neutral. 240 Volt heaters used on 208V will supply only 75% of heat. All three phase systems provide 1.73 times as much power as a single phase system of same 120 V, 1 phase, 208V 1 phase and ampacity for only about 1.25% 3 phase loads can be used. the cost. More economical. All panel spaces can be used. No wild leg. 6/20/02 Chapter 2: Basic Types of Ac Power Systems 1/3 120/240 Volt, 3 phase, 4 wire Delta Application Used mainly in shops where 240V 1 phase equipment exists and where 120V single phase is a minor part of the load. Usually used with a 120/240V single phase panel because L2 is a wild leg. If one line, either L1 to neutral is loaded up to ampacity on 120 volt loads, no other 3 phase loads may be placed on the system. Line 2 to neutral is 208 volts to neutral. “Wild leg” can’t use 1/3 of panel space for 120 volt loads because every 3rd pole is 208 volts to ground. (120V, 1 phase, 240V loads 1 phase and 2 phase can be used). Hard to Balance 120 and 240V, 3 phase and 1 phase equipment easy to obtain. Should not use if 120V load is more than 25% of load. 6/20/02 Chapter 2: Basic Types of Ac Power Systems 2/3