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					                     AUTOMATIC VOLTAGE REGULATOR (AVR)
                              TRANSFORMATOR




I. TIMER VOLTAGE
The voltage regulator (Voltage Regulators) are used to regulate the output voltage from
the transformer to keep the output voltage remains constant, Voltage Regulators There
are two types of induction and the type of step-type regulators. In today's era of step
type regulator has replaced the type of induction.
Step type voltage regulator is basically an autotransformer with a tap or step in a series
of turns. In high voltage transformers Voltage Regulators step type can generally be
operated in a condition known as unburdened and On Load Tap Changer (OLTC).
It is very important regulator designed to correct the phase voltage from 10 percent
raise (boost) to 10 percent lower / against (buck) (+10 percent) in 32 steps, with 5 / 8
percent change in voltage per step. Note that the voltage regulation fully with the range
of 20 percent, in other words, if 20 percent of full range of regulation by 32 steps, then
found 5 / 8 percent per step regulation.
II. (LINE-DROP COMPENSATION)
 Voltage Regulators at the substation is used to get a transformer secondary voltage
 remains constant despite fluctuating voltage on the primary side of an imaginary setting
 or set point value regardless of the size (magnitude) or the employment factor (power
 factor) of the load.
 The point of regulation (regulation point) are usually chosen at a location between the
 regulator and at the end of the feeder (the end of the feeder). This will be maintained
 automatically by the dial settings by setting the element resistance and reactance of the
 unit called a line-drop compensator.
 At zero load condition determining the value of resistance between the regulator and
 the regulation point. R dial settings on the line drop compensator can be determined
 from:
                                            CTP
                                   Rset        xReff V
                                            PTs


 Keterangan :
         CTp = rating dari besaran primer CT
         PTs = Potential transformer’s turns ratio : Vpri/Vsec




                                                                                              Primary lateral

                                                                                     Feeder
    Gardu Induk
                                                                                     point
                  Transformator
                                          IL
                                                                   RL         XL


          OLTC                            CT                         Feeder

                                                                  Voltage
                            PT       RL        XL                 Regulator                      To first customer
                                  Vreg              VVRR          Relay

                                                            VRR




                                                      Vreg

                                                                                   ILXL

                                               VVRR

                       θ
                                                     ILRL
                           IL
Gambar 1 Schematic Diagram Sederhana dan Phasor Diagram dari Rangkaian Kontrol
         dan Rangkaian Line-Drop Compensator dari Suatu Step atau Induksi Voltage
         Regulator

   Reff = resistance value (resistance) is effective conductor of the feeder substation
   up to the point of regulation (regulation point)
                              I  Sl
                  Reff  re x        
                                2
          When:
          Re      =     resistance    of     conductor     feeder station regulation
          up to the regulation point, Ώ / mi per conductor
          Sl = length of the three phase conductors of the feeder between
          regulation station to the substation
          l = length of feeder, mi

   Juga, nilai X dial setting dari line-drop compensator dapat ditetapkan dari :

                               CT p
                   X set              xX eff V
                               PTs

          dimana: Xeff = nilai reaktance efektif konduktor feeder dari GI
                        sampai dengan titik pengaturan (regulation point),Ώ

                                      I  Sl
                   X eff  X l x             
                                        2

          dimana : XL = reaktansi induktif dari konduktor feeder, Ώ/mi

   If the value of R and X are set to the total connected load, is more than just to a group
   of customers, the value of resistance and reactance determined from:
                                                    n

                                                   V      DR I
                                          Reff    I 1
                                                                  
                                                          IL

      dan :
                  n

                 V
                 I 1
                         DR         I L.1 .ra.1 xl1  I L.2 ra.2 xl2  .......... .....  I L.n ra.n xln
                               I


      dimana :
                 VDR I = voltage drop from one feeder line resistance between the
                         regulator station to the regulation point, V / section
                 n

                  V DR = The total voltage drop of Resistance of Feeder Line between
                 I 1      I

                            the regulator station with the regulation point, V
                 I L.1    The amount of load current on the feeder section one, A
                 ra1 = resistance dari konduktor feeder section satu,Ώ/mi
                  l1 = feeder section of the conductor length, mi

      Juga untuk nilai X dial setting dari the line-drop compensator ditetapkan dari :
                                                          n

                                                         V      DX I
                                               X eff    I 1
                                                                        
                                                                IL

     dan :
                       n

                  V I 1
                                 DR        I L.1 .xa.1 xl1  I L.2 xa.2 xl2  .......... .....  I L.n xa.n xln
                                      I




     dimana :
                VDR I = drop tegangan dari line reactance satu feeder diantara regulator
                                      station dengan regulation point, V/section
                 n

                V
                I 1
                            DR
                                     = Total drop tegangan dari Line Reactance dari Feeder diantara
                                 I

                               regulator station dengan regulation point,V
                     I L.1    Besarnya arus beban pada feeder section satu,A
                  xa1 = reactance dari konduktor feeder section satu,Ώ/mi
                 l1 = panjang konduktor feeder section satu,mi




     Because of the above methods only describe to determine the effective value of R
     and X are quite troublesome. Suggested an alternative and practical method to
     measure the current (IL) and the voltage regulator in a location and set point
     (regulating point). The difference between the two voltages is the total voltage
     drop between the regulator and the set point, which can also be defined as:
                           VD  I L .Reff .Cos  I L . X eff .Sin ....V

From the value of Reff and Xeff can be easily determined when the work factor of the
load feeder and the average ratio r / x ratio of feeder conductors between the regulator
and the regulating point known
Figure 2 below provides an example to determine the voltage profile for the peak load
and normal load. basic value of the feeder primary voltage is 120-V base.
                                        Voltage Regulator


                                                                                     Primary Feeder




                                                  First distributor
                                  130               transformer
Primary Voltage (120 volt base)




                                  128
                                                                                                      Peak load profile
                                  126

                                  124

                                  122

                                  120

                                  118                             Regulation point              (a)
                                                                                                                          Light load profile
                                  116


                                              0             1          2             3          4              5            6             7    8

                                                                           Feeder length beyond regulator,mi

                                                                                              (b)

            Figure 2 Example One-line diagram in Feeder Voltage Profile


            One-line diagram and voltage profile of a distribution feeder with a load under a
            voltage regulator, the location of: (a) one-line diagrams, and (b) peak and light load
            profile point for regulating visible shadow line drop compensator settings.


            The assumption that the size of the conductor between the voltage regulator to the
            nearest distribution transformer is <2 / 0 Cu conductor dg 44-in flat spacing R and X
            values are 0.481 and 0.718 Ώ / mi. PT and CT ratio: 7960:120 and 200:5, the distance
            regulating point 3.9 mi. Line-drop compensating settings are:


                                                           Rset = 200x(120/7960)x0,481x3,9 = 5,656 
                                                           Xset = 200x(120/7960)x0,718x3,9 = 8,4428 
                                                           Voltage-regulating relay setting adalah = 120,1 V
                                                       Subtransmission


                                           Base Vst = 69 kV

                              OLTC

     ST = 15 MVA
                                     Distribution substation
   ZTp.u = (0+j0,08) pu              transformer


                                           Base Vp = 13,2 kV


                                                               S1



                                    S=0                                           SRP           S=l

                                                   Feeder regulator station




              Gambar 3 One-Line Diagram Gardu Induk dengan Feeder 13,2 kV


  Figure 3 illustrate the elements of a distribution substations supplied from a duct
  system      subtransmisi   with     loops       and          radial    feeder    supplying   some
  OLTC Transformer substation can be used to set the primary side voltage distribution
  (Vp) bus, although subtransmisi voltage (VST) and voltage drop (IZt) Transformer
  influenced by the load but remain constant Vp


MR TYPE AVR MK 30
MR voltage regulator electronics brands, type MK 30 automatic control of the
transformer serving the motor controller on-load tap changer.
Control system follows the principle of step-by-step, single control pulse to operate the
tap changer from one tap position to tap the other positions.
OLTC drive motor unit without the function of the step-by-step control pulse received
continuously, the which is also available.
In two cases RAISE or LOWER control signals generated by the voltage regulator and
motor drives Whenever rumored to measure the voltage deviation from the conditions
outside the specified settings.
Load affects the voltage drop occurs on the line impedance, for example on a single
feeder line between the transformer with the load, can be compensated by raising the
Desired value either by means of the incorporated resistive and inductive line network
simulation (Line-Drop Compensator) or with the apparent resistance drop compensation
(Z-Compensation)
Voltage level may drop lower in the sense required the release of the load (load shedding)
there is load shedding facilities with a three-step programming choices through the relay
contacts or switches.
Trouble free operation is ensured by the incorporated largely under-voltage and
overcurrent blocking functions and the overvoltage monitoring.
          7                  9             10          12        5       13   6




                                                                                                               3
                                                                                   KV
                                                                                   V
                                                                                                               4
                                                                                   %
                                                                                    X
                      BASIC FUNCTION
                                                                                                SCROLL
    TIME 1                  TIME 1        VOLTAGE                             I>
                                                       U<            U>
    TIME 2                 TIME            LEVEL                              K
8                          2
                                                             MONITORING

    lin         Int          Local        Remote

                                                                                                                   2
            LINE DROP                                        LOADSHEDDING
          COMPENSATING


          U<                U>            ADJUST
                                            kV         1             2        3
    VOLTAGE                LIMIT


                                      V          KV
          LDC          Z-COMP


                                                                                           MODE OF OPERATION


                                                                                                   AUTO
                                                                                          MANUAL
                      16             18     19
                                                      21    20                            OFF

                                                                                                               1




          MK 30
          VOLTAGE CONTROL                                                               MR MASCHINENFABRIK
                                                                                           REINHAUSEN
          MADE IN WEST GERMANY




     Gambar 3 Elemen Kontrol dan Indikator dari panel depan AVR MK30

				
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posted:10/2/2011
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