﻿148 
  Dr. 
  Prysdale 
  on 
  the 
  Use 
  of 
  SJiunts 
  and 
  Transformers 
  

  

  path, 
  a 
  its 
  area 
  of 
  cross 
  section, 
  and 
  I 
  s 
  the 
  total 
  secondary 
  

   impedance 
  (reduced 
  to 
  1 
  turn), 
  we 
  have 
  

  

  -A. 
  

  

  Effective 
  core 
  E.M.F. 
  e 
  = 
  ^?f 
  = 
  °? 
  P 
  volts 
  per 
  turn; 
  

  

  10 
  8 
  */2xl0 
  8 
  l 
  

  

  Secondary 
  ampere 
  turns 
  A„ 
  = 
  ■=- 
  = 
  /-> 
  ^ 
  , 
  

   \ 
  l 
  " 
  I. 
  ^2xl0 
  8 
  L 
  

  

  from 
  which 
  

  

  f> 
  = 
  y/2 
  x 
  10 
  8 
  I,A, 
  ^7) 
  

  

  op 
  

  

  Assuming 
  the 
  core 
  loss 
  to 
  be 
  tjB 
  c 
  ergs 
  per 
  c.c. 
  per 
  cycle 
  : 
  — 
  

   Total 
  core 
  loss 
  

  

  Wm= 
  juF 
  ' 
  

  

  and 
  the 
  core-loss 
  ampere 
  turns 
  

  

  A. 
  = 
  & 
  = 
  «^,l 
  J- 
  ySx-KWA 
  l^ 
  . 
  . 
  ( 
  2 
  8) 
  

  

  e 
  ic 
  \ 
  ap 
  J 
  

  

  For 
  the 
  magnetizing 
  current 
  

  

  a 
  _ 
  10 
  B/ 
  

  

  4:7T 
  yLt 
  

  

  A, 
  = 
  filA 
  (29) 
  

  

  These 
  relations 
  are 
  sufficient 
  to 
  enable 
  the 
  magnetizing 
  and 
  

   core-loss 
  currents 
  to 
  be 
  calculated 
  when 
  the 
  total 
  secondary 
  

   impedance 
  is 
  known. 
  The 
  resistances 
  are 
  of 
  course 
  readily 
  

   calculable, 
  while 
  the 
  equivalent 
  inductance 
  of 
  the 
  whole 
  

   transformer 
  for 
  a 
  single 
  primary 
  and 
  secondary 
  winding 
  may 
  

   be 
  calculated 
  from 
  the 
  following 
  formula, 
  deduced 
  from 
  that 
  

   given 
  by 
  Prof. 
  Kapp 
  : 
  

  

  l 
  = 
  c 
  tSle 
  2(3KS+T) 
  • 
  • 
  • 
  • 
  (*>) 
  

  

  P 
  being 
  the 
  mean 
  perimeter 
  of 
  the 
  coils 
  in 
  inches, 
  

   L 
  the 
  length 
  of 
  gap 
  from 
  iron 
  to 
  iron, 
  parallel 
  to 
  

  

  insulation 
  between 
  coils, 
  

   S 
  the 
  thickness 
  of 
  the 
  insulation 
  in 
  inches, 
  

   K 
  the 
  number 
  of 
  sections 
  per 
  coil, 
  

   T 
  the 
  length 
  of 
  the 
  winding 
  space, 
  

   and 
  C 
  a 
  constant 
  given 
  as 
  44 
  for 
  core 
  and 
  55 
  for 
  shell 
  

  

  type 
  transformers. 
  

  

  