Electric Power Generation, Transmission, and Distribution

VS¼ 1 

N 2

N 1



Vl IL¼ 1 

N 2

N 1



IS (21:81)

VS¼aRVL IL¼aRIS (21:82)

aR¼ 1 

N 2

N 1

(21:83)

Equations (21.82) and (21.83) are the necessary defining equations for modeling a regulator in the raise
position.

21.1.4.2 Voltage Regulator in the Lower Position

Figure 21.16 shows the detailed and abbreviated drawings of a regulator in the lower position. Note in
the figure that the only difference between the lower and the raise models is that the polarity of the series
winding and how it is connected to the shunt winding is reversed.

ls

s R s

SL

L

SL

L L

ls N 2

VS

V (^1) V
N 1 L
V 2
l 2
lL lL
lS
VS
VL
I 1

• 
  


• 
  


• 
  
  
  
  • 
    
  
  
  
  


• 
  

  −
  −
  −−
  − −

  
  


• 
  

  FIGURE 21.15 Type B voltage regulator in the raise position.
  IS
  IS
  I 2
  V 2
  I 1
  V (^1) VL
  VS
  N 1
  N 2

  
  


• 
  


• 
  

  SL

  
  


• 
  

  s
  −
  −
  VL
  IS
  IL

  
  


• 
  


• 
  

  − −
  −−
  R
  L
  IL L
  L
  SL
  s

  
  


• VS
  FIGURE 21.16 Type B regulator in the lower position.