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Continuous and Alternating Current Machinery Problems
     

Continuous and Alternating Current Machinery Problems

by William Thomas Ryan
 
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This is an OCR edition with typos.
Excerpt from book:
CHAPTER VIII THE TRANSFORMER 1. A Certain 10-kva. transformer requires 0.088 ampere when the high-tension side is connected to 2200-volt mains, and the secondary is open

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Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free.
This is an OCR edition with typos.
Excerpt from book:
CHAPTER VIII THE TRANSFORMER 1. A Certain 10-kva. transformer requires 0.088 ampere when the high-tension side is connected to 2200-volt mains, and the secondary is open circuited. The hysteresis and eddy-current losses are 110 watts. Required the magnetizing current. Note. The no-load primary current, In, is the resultant of the iron loss component, /, and the magnetizing component, Iw is equal to the iron losses in watts divided by the primary voltage. la, is in phase with the primary voltage and Im is in quadrature. 2. What would a watt meter read if it were placed in the primary circuit specified in problem 1? What is the angle of phase displacement between the impressed primary voltage and /o? 3. There are 1200 turns on the primary of the above transformer, and 120 turns on the secondary, (a) What will the secondary voltage be with no load on the secondary? (6) A sufficient number of incandescent lamps, unity power factor, are connected to the secondary of the above transformer to cause 40 amperes to flow in the secondary. Required the current and its phase displacement in the primary. Note. Since the ratio of transformation is 10 to 1, 40 amperes in the secondary will cause an increase of 4 amperes in the primary, and since the power factor is unity it will be in phase withthe primary voltage, therefore in phase with 7W and in quadrature with Im. 4. The area of the magnetic circuit of a certain 15-kva. transformer is 12 sq.ins. The mean length of the magnetic circuit is 36 ins. The maximum flux density is 50,000 lines per square inch. A fair value for the permeability at this density would be 2650. There are 1000 turns on the primary. Required the magnetizing current. Note. The formula, t =QAirNIiA/l applies, but it must be remembered that 7 is the m...

Product Details

BN ID:
2940024377956
Publisher:
J. Wiley & sons, inc .; [etc., etc.]
Sold by:
Barnes & Noble
Format:
NOOK Book
File size:
60 KB

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