tsm%20363%20exam 2

tsm%20363%20exam 2 - Agricultural and Biosystems...

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Agricultural and Biosystems Engineering Dept. Iowa State University 1 01 1 9/06 SKW Nme e TSM 363 - Exam 2 Part 1 - Formula sheet (8 %" x 1 I", one-side, anything) Multiple Choice and Short Answer:. 2 points each (40%) 1) Materials which are good insulators a) have many free electrons. @ have few fiee electrons. c) have no electrons d) must have no resistance. e) have atoms which are positively charged 2) Duplex convenience outlets in the dining room would be served by this circuit: 15 A general purpose circuit supplying dining room lights 30 A appliance circuit 20 A appliance circuit 3) This is an advantage of 3-phase power, compared to single-phase power: a) larger wire size required b) greater safety because of no current-carrying neutral 0 simple and low-cost motors will operate with one wire disconnected 4) A voltage of 208 Volts is measured between two wires on a 3-phase wye load, connected to a 3-phase wye service. This is a @ line voltage b) phase voltage c) both phase and line d) neither phase or line e) can't tell fiom info given 5) This type conductor is suitable for direct burial @ USE b) SE Page 1 of 6
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6) Phase current and line current on a 3-phase load a) are always equal b are never equal d are equal on a wye load d) are equal on a delta load 7) A farm shop has a 35-A, 230-V welder, 12 lighting and convenience outlets and a 3kW electric heater. The building demand at 230 V would be calculated to be about 57 amps 12x 1.5 = 18/2 = qA c) 66 amps -= d) 63 amps 13.W = 13A 230 V e) none of the above + 35A 8) A wild phase is present on this type of service: 53A :::a c) both wye and delta d) neither wye nor delta 9) Voltage drop determines wire size for: a) very short distances @ very long distances c) heavy loads d) branch circuits e) aluminum conductors 10)
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tsm%20363%20exam 2 - Agricultural and Biosystems...

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