239.  A wattmeter uses
A. D' Arsonval movement
B. electro-dynamometer movement
C. hot-wire principle
D. none of the above

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240.  What is the phase relationship between line currents in a delta system?
A. 300 between each line current
B. 600 between each line current 1200 between each line current
C. 450 between each line current
D. none of the above

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241.  All a.c. equipment is rated in kVA because
A. kVA > kW
B. kVA < kW
C. of temperature rise limitation
D. none of the above

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242.  When the p.f. is improved, lagging reactive power supplied to the load
A. decreases
B. increases
C. remains unchanged
D. none of the above

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243.  If wattmeter is normally phased and it indicates reverse reading, the current and voltage are
A. more than 900 out of phase
B. less than 90? out of phase
C. insufficient data
D. none of the above

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244. A balanced A-connected load is converted to equivalent balanced Y load. Then
A. Zy = ?3 ;
B. ZY
C. Zy = 3Z6
D. none of the above

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245. The line currents in a 3-phase, 4-wire system are 9 L ? 60?A, 15 L 40?A and 12 L 130?A. The neutral wire current is
A. 13.8 L 53-1?A
B. 6.8 L ?43.5?A
C. 36 L 110?A
D. none of the above

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