EP-3: Electrical procurement – transformers course


Course Description:

This course is intended to prepare the target persons with the ability to understand and recognize different types, components and accessories of transformers. 

The target Persons:

Design engineers, new graduate engineers, under graduate engineering students, site field engineers, maintenance engineers and electrical technicians.

Skills Development:

On completion of this course the target person will be able to:

  • understand transformer terms and definitions
  • recognize different types, components and accessories of  transformers
  • specify correctly any type of transformer for procurement phase

Course outline

2-Transformer design:
·        Core
·        Windings
·        Tank
·        Insulation materials


A-According to transformed voltage level:
·        Step up transformer
·        Step down transformers

B-According to construction:
·        Core type
·        Shell type

C-According to application
·        Power transformers
                               -  Generatorstep-up transformers
             -  Step-down transformers
             -  System intertie transformers:
                               - Phase Shifting Transformers
                               - HDVC Transformers
             -  Industrialtransformers:
                               - Furnace Transformers (Part One) (Part Two)
                               - Convertor Transformers
             -  Traction transformers
·        Distribution transformers
·        Instruments transformers
·        Rectifier transformers
·        Earthing transformers
·        Pole mounted transformer
·        Furnace transformer
·        Regulating transformer (Auto transformer)
·        Isolation Transformers

D-According to insulation and cooling materials
Oil immersed transformers
Askral transformers
Silicon fluid transformers
Dry type transformers:
Normal type
Cast Risen type
Gas filled type

E-According to number of phases
·        Single phase
·        Three phase

F-According to windings connection methods
·        Star-Star
·        Delta-Delta
·        Star-Delta
·        Delta-Star
·        3-Windings Star-Delta-Star
·        Scott Transformers
·        Zig-Zag Transformers
·        Tap-Changing Transformers


4-K-factor transformer

5-Transformer components:
A.     Terminals
B.     Bushings:
·        Low voltage
·        Condenser
·        High current
C.     Cable connection box
D.     SF6 connection
E.      Coolers:
·        Radiator
·        Corrugated tank
·        Fans
·        Heat exchangers
·        Oil-water coils
·        Oil pumps

F.      Voltage regulating equipments:
·        Off circuit tap changer
·        On load tap changer


6-Transformer accessories:
a.       Thermometer
b.      Built-in current transformer
c.       Dehydrating breathers
d.      Oil preservation tank (conservator tank)
e.       Oil level indicator
f.        Pressure relief devices
g.       Sudden Pressure relief devices
h.       Over voltage protection devices:
·        Internal
·        External
i.         Combustible gas detector
j.        Flow indicator
k.      Transport wheels/skids
l.         Drain valve

  7-Transformer paralleling:
·        Single phase paralleling
·        Three phase paralleling

    8-Transformer protection:
·        Protective devices installed on tank
·        Bockholtz relay

    9-Transformer ratings:
·        Single phase transformers
·        Single phase transformers

   10-Transformer nameplate data

11-Transformer testing:
a)      Routine tests:
·        Winding resistance
·        Voltage ratio and check of phase displacement
·        S.C impedance and load losses
·        No-load losses and current
·        Dielectric routine tests
·        Tests on load tap changers
b)      Type tests:
Temperature rise test
Dielectric type test

12-Transformer troubleshooting

13-Transformer dictionary 

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