﻿[ 
  SG6 
  1 
  

  

  XCII. 
  Effect 
  of 
  Temperature 
  on 
  the 
  Hystereds 
  Loss 
  in. 
  Iron 
  

   in 
  a 
  Rotating 
  Field. 
  Bij 
  W. 
  P. 
  Fuller, 
  B.Eng., 
  and 
  

   H. 
  Grace, 
  B.Eng,'' 
  

  

  IT 
  was 
  shown 
  by 
  Professor 
  Baily 
  f 
  that 
  the 
  hysteresis 
  losses 
  

   due 
  to 
  a 
  rotating 
  field 
  in 
  iron 
  reached 
  a 
  maximum 
  value 
  

   with 
  an 
  induction 
  density 
  (B) 
  o£ 
  about 
  16,000 
  C.G.S. 
  units. 
  

   With 
  a 
  value 
  of 
  B 
  equal 
  to 
  20,000 
  the 
  hysteresis 
  was 
  ap- 
  

   proximately 
  2V 
  ^^ 
  the 
  value. 
  These 
  results 
  were 
  confirmed 
  

   by 
  Messrs. 
  Beattie 
  & 
  Clinker 
  J. 
  The 
  experiments 
  described 
  

   below 
  were 
  undertaken 
  in 
  order 
  to 
  determine 
  to 
  what 
  extent 
  

   the 
  results 
  attained 
  by 
  Professor 
  Baily 
  were 
  modified 
  by 
  

   variation 
  in 
  temperature. 
  

  

  In 
  these 
  experiments, 
  the 
  rotating 
  field 
  was 
  produced 
  by 
  

   means 
  of 
  two 
  phase-currents. 
  Fig. 
  1 
  shows 
  the 
  arrangement, 
  

   the 
  two 
  magnetizing 
  coils 
  carrying 
  the 
  two 
  phase-currents 
  

   being 
  marked 
  E, 
  D. 
  A 
  is 
  a 
  slab 
  of 
  plaster 
  2 
  cms. 
  thick 
  and 
  

   22 
  cms. 
  square, 
  having 
  a 
  circular 
  hole 
  8^ 
  cms. 
  diameter 
  in 
  

   the 
  centre. 
  At 
  the 
  top 
  and 
  bottom 
  of 
  the 
  hole 
  the 
  heaters 
  B 
  

   are 
  placed, 
  and 
  in 
  the 
  chamber 
  so 
  formed 
  the 
  iron 
  specimen 
  

   is 
  suspended. 
  Each 
  heater 
  was 
  made 
  by 
  winding 
  No. 
  40 
  

   s.w.G. 
  nickel 
  wire 
  zigzag 
  fashion 
  over 
  the 
  surface 
  of 
  a 
  

   circular 
  piece 
  of 
  mica. 
  Its 
  resistance 
  cold 
  was 
  13 
  ohms, 
  but 
  

   increased 
  rapidl}^ 
  with 
  temperature. 
  With 
  the 
  two 
  in 
  series 
  

   a 
  current 
  of 
  1*6 
  amps, 
  at 
  180 
  volts 
  produced 
  a 
  maximum 
  

   temperature 
  of 
  500° 
  C. 
  at 
  a 
  point 
  close 
  to 
  the 
  iron 
  disk. 
  The 
  

   specimen 
  used 
  was 
  a 
  circular 
  disk 
  of 
  iron 
  4 
  cms. 
  diameter, 
  

   •027 
  thick 
  : 
  it 
  was 
  attached 
  by 
  nuts 
  to 
  a 
  brass 
  spindle 
  C, 
  

   which 
  had 
  a 
  weio;ht 
  attached 
  to 
  one 
  end, 
  and 
  a 
  concave 
  mirror 
  

   at 
  the 
  other 
  for 
  indicating 
  the 
  motion 
  of 
  the 
  specimen. 
  The 
  

   whole 
  was 
  supported 
  by 
  a 
  bifilar 
  suspension, 
  the 
  sensitiveness 
  

   of 
  which 
  could 
  be 
  varied 
  by 
  altering 
  the 
  weight 
  or 
  by 
  varying 
  

   the 
  distance 
  apart 
  of 
  the 
  supporting 
  wires. 
  The 
  weight 
  of 
  

   the 
  whole 
  moving 
  part 
  was 
  285 
  grams. 
  

  

  The 
  two 
  magnetizing-coils 
  D 
  D, 
  belonging 
  to 
  one 
  phase, 
  

   are 
  each 
  made 
  by 
  winding 
  14 
  turns 
  of 
  7/14 
  asbestos-covered 
  

   cable. 
  The 
  two 
  coils 
  are 
  arranged 
  to 
  slide 
  over 
  the 
  plaster 
  

   slab 
  to 
  within 
  a 
  short 
  distance 
  of 
  each 
  other, 
  at 
  the 
  centre. 
  

   The 
  coils 
  for 
  the 
  second 
  phase, 
  E 
  E, 
  are 
  placed 
  so 
  as 
  to 
  produce 
  

   a 
  field 
  at 
  right 
  angles 
  to 
  that 
  of 
  D 
  D. 
  They 
  are 
  of 
  the 
  same 
  

   shape 
  as 
  D 
  D, 
  so 
  that 
  the 
  two 
  together 
  produce 
  a 
  close 
  ap- 
  

   proximation 
  to 
  a 
  uniform 
  rotating 
  field 
  at 
  the 
  centre 
  of 
  the 
  

   coils 
  where 
  the 
  specimen 
  is 
  placed. 
  The 
  large 
  coil 
  was 
  found 
  

  

  * 
  Communicated 
  bv 
  the 
  Physical 
  Society 
  : 
  read 
  May 
  14, 
  1909. 
  

   t 
  Phil 
  Trans. 
  1896. 
  

   I 
  * 
  Electrician/ 
  1890. 
  

  

  