Current transformer (CT) is used for measurement of Current & protection of major components and to provide continuity of operation in power system. When current in a circuit is too high to directly apply to measurement or protection relays, a current transformer produces a reduced current accurately proportional to the current in the circuit, which can be conveniently connected to measuring and recording instruments. Current transformer also isolates the measuring instruments from what may be very high voltage in the monitored circuit. It commonly used in metering and protective relays in the electrical power industry.
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
Maintenance : Maintenance free
Spare Parts : No special tools, no serviceable parts or spare parts are required
|Highest System Voltage||72,5||123||145 kV||245 kV||420 kV||550 kV|
|One minute power frequency voltage||140||230||275kV rms||460 kV rms||630 kV rms||680 kV rms|
|Lightning impulse voltage||325 kV Peak||550 kV Peak||650 kV Peak||1050 kV Peak||1425kV Peak||1550kV Peak|
|Rated frequency||50/60 Hz||50/60 Hz||50/60 Hz||50/60 Hz||50/60 Hz||50/60 Hz|
|Short time thermal current||63kA/1sec||63kA/1sec||63kA/1sec||63kA/1sec||63kA/1sec||63kA/1sec|
|Dynamic withstand current||157,5kA, peak||157,5kA, peak||157,5kA, peak||157,5kA, peak||157,5kA, peak||157,5kA, peak|
|Total Creepage Distance||25/31mm/kV||25/31mm/kV||25/31mm/kV||25/31mm/kV||25/31mm/kV||25/31mm/kV|
|Primary Current||'Upto 4000A & higher currents can also be supplied on request'||Upto 4000A & higher currents can also be supplied on request||Upto 4000A & higher currents can also be supplied on request||Upto 4000A & higher currents can also be supplied on request||Upto 4000A & higher currents can also be supplied on request||Upto 4000A & higher currents can also be supplied on request|
Thermal and Dynamic Ratings
Continuous Thermal Current
Oil impregnated paper, high dielectric strength, low dielectric losses.
Graded layers with well rounded edges enable a uniformly distributed field over the whole unit.
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 volume variations are compensated with stainless steel bellows placed in the head of the transformers. 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 CT.
Primary terminals are made from tin plated copper or aluminium.
Vertical and horizontal primary terminals are available.
Dimensions depend on rated primary current.
Stud, nema pad or clamp type primary terminals are available.
Grain oriented silicon steel is used.
The core shapes are toroidal with or without air gap.
Electrolytic copper suitable to withstand rated continuous current and short time thermal current is used for primary winding.
Enamelled electrolytic copper wire is used for Secondary winding.
The housing head is fabricated from corrosion protected aluminium.
Every housing is subject to pressure and vacuum test before assembly.
Secondary Terminal Box
Hinged type boxes are used and are sealable on request. They are made of galvanised steel stainless steel.
Clamp type secondary terminals are used. Other secondary terminals are available on request. Earthing
Earthing terminals are located on the base of the transformers.
Clamp type terminals are available on request.
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.
Steel support structure
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
Before the assembly, following visual checks should be made;
There are no oil leaks,
The porcelain is not damaged,
The aluminium protective cover on the bellows 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.
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.