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Capacitive Voltage Transformers

Oil Immersed Voltage Transformers


Capacitive Voltage Transformers

Capacitive Voltage Transformers (CVTs) have been widely used within transmission power systems for applications ranging from high-voltage to ultra high-voltage. CVTs are primarily used for voltage measurement, providing voltage signals to metering units, protection relay devices, and automatic control devices.

EMEK manufactures oil/paper insulated instrument transformers up to 550kV nearly 100.000 units since 1969.

Features of this design and contraction include:

· Hermetically Sealed Construction

· High Seismic Performance

· Stainless Steel, Aluminium and/or Hot deep galvanized metal parts

· Durability in extreme weather conditions

· Long life time expectancy

Frequency: 50Hz, 60Hz

Standards: TSE, IEC, ANSI, GOST, BS&AS and other standards upon request

Insulators: Porcelain or Composite Polymer Insulators

Insulating Oil: Mineral oil in conformity with standards in EMU and synthetic in capacitor unit.

Maintenance: Maintenance free

Spare Parts: No special tools, no serviceable parts or spare parts are required

Highest System Voltage72,5 kV123 kV145 kV170 kV245 kV300 kV362 kV420 kV
One minute power frequency voltage140 kV rms230 kV rms275 kV rms325 kV rms460 kV rms460 kV rms510 kV rms630 kV rms
Lightning impulse voltage325 kV Peak550 kV Peak650 kV Peak750 kV Peak1050 kV Peak1050 kV Peak1175kV Peak1425kV Peak
Rated frequency50/60 Hz50/60 Hz50/60 Hz50/60 Hz50/60 Hz50/60 Hz50/60 Hz50/60 Hz
Short time thermal current50kA/3sec50kA/3sec50kA/3sec50kA/3sec50kA/3sec50kA/3sec50kA/3sec50kA/3sec
Dynamic withstand current125kA, peak125kA, peak125kA, peak125kA, peak125kA, peak125kA, peak125kA, peak125kA, peak
Total Creepage Distance25/31mm/kV25/31mm/kV25/31mm/kV25/31mm/kV25/31mm/kV25/31mm/kV25/31mm/kV25/31mm/kV
Technical Details
Type Tests


  • 50 Hz, 60 Hz

Secondary Voltage -100/√3, 110/√3, others on request.

Rated Voltage Factor 1.2xUm cont/1.9 for 30s – 1.9 for 8h – 1.5 for 30s


  • Oil impregnated paper, high dielectric strength, low dielectric losses.

Insulating Oil

  • The insulating oil is mineral oil in conformity with IEC 60296.
  • Before impregnation, moisture and gases are removed from the oil by special processes.
  • Drain plug for taking samples and oil refilling facilities are provided on request.
  • Floating type oil level indicator is standard supply.

Oil Impregnation

  • Heat and vacuum are applied to the fully insulated windings after assembly of the voltage transformer for drying purposes, followed immediately by the oil impregnation procedure.

Hermetic Seal

  • Oil volume variations are compensated with stainless steel or PTFE capacitor stack bellows placed in the. With this facility there will be no contact between air and oil in the transformers.
  • The dielectric strength will remain unchanged for the life time of the CVT.


  • Brown, Grey glazed porcelain or polymer.

Primary Terminals

  • Primary terminals are made from tin plated brass, capper or aluminium.
  • Vertical and horizontal primary terminals are available.
  • Stud, nema pad or clamp type primary terminals are available.


  • Grain oriented silicon steel is used.
  • Enamelled electrolytic copper wire is used for Secondary winding. Secondary winding in EMU.


  • All bracelets used on transformers are made from aluminium alloy.


  • Every housing is subject to pressure and vacuum test before assembly.

EMU Tank

  • Tank of the transformers are fabricated from steel and galvanised.

Name Plate

  • Name plates are stainless steel.

Secondary Terminal Box

  • Hinged type boxes are used and are sealable on request. They are made of galvanized steel.
  • Clamp type secondary terminals are used. Other secondary terminals are available on request. Earthing
  • Earthing terminals are located on the tank of the transformers.
  • Clamp type terminals are available on request.


  • External surface of the transformers, which are already corrosion protected, are additionally painted grey. Other colours are available on request.

Earthquake Design

  • Standard design is up to 0.6g.

Ambient Temperature

  • Standard design is suitable for temperature range -50 °C to +50°C. Other ranges on request. Mechanical Strength
  • Applied load to the primary terminal in horizontal and vertical is in conformity with related IEC standards.


  • Standard design is suitable up to 1000 m above sea level.

Optional Accessories

  • PLL accessories
  • Steel support structure
  • Primary connectors
  • Marshalling box


  • Maintenance free, simple recommendations;
  • Clean the porcelain bushing at regular intervals depending on the degree of pollution.
  • Ensure that there is no oil leakage.

Spare Part & Special Tools

  • There are no user serviceable parts, therefore no spare parts or special tools are required for maintenance.


  • Before the assembly, following visual checks should be made;
  • There are no oil leaks,
  • The porcelain is not damaged,
  • There is no damage on the primary terminals,
  • The oil level indicator indicates sufficient oil level.


  • The transformers are packed in rugged wooden crates which are suitable for overseas transportation.
  • The transformers are encapsulated in polyethylene covers to keep them from environmental effects.
  • Wooden crates can be lifted by either a fork lift or by a crane with slings.
  • Other technical specifications may be available upon request.
Balıkhisar Mahallesi, Köyiçi Kümeevleri No: 574, Akyurt, 06750 Ankara - Türkiye
(+90) -312 -398 -0181
(+90) -312 -398 -0474
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About Us

Emek is a labor-independent, internationally operating manufacturer of instrument transformers.

Its reliable and high quality products have been repeatedly tested in local and international laboratories. Its experience has been strengthened with transformers working in the system for half a century, it has improved and renewed itself every day.

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