Medium-voltage instrument transformers
Current instrument supporting transformer
CTO 15
Current instrument supporting transformer CTO 15 is designed for measurement and protection of high voltage distributing equipment for outdoor design for nominal primary currents of 5-600 A and for the highest voltage of system of 25 kV.
The value of secondary current is 5 A or 1 A with the possibility of combination. The accuracy classes for the circuits of measurement are 0.2, 0.2S, 0.5, 0.5S, 1, 3, for the circuits of protection are 5P, 10P.
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Description
Current instrument supporting transformer CTO 15 is designed for measurement and protection of high voltage distributing equipment for outdoor design for nominal primary currents of 5-600 A and for the highest voltage of system of 25 kV.
The value of secondary current is 5 A or 1 A with the possibility of combination. The accuracy classes for the circuits of measurement are 0.2, 0.2S, 0.5, 0.5S, 1, 3, for the circuits of protection are 5P, 10P.
The transformers fulfill the required accuracy class at intervals from 25 % to 100 % of rated load. The terminal working current is 120 % IN, in case of the agreement of the producer and the customer it is possible to deliver also the other values, for example 200% IN.
Creepage length is 650 mm.
Transformers CTO 15 are constructed as transformers with single-turn or multi-turn primary winding. The construction of these transformers allows the switching on the secondary side.
The secondary winding is wound on a magnetic core made from grain oriented sheets, or alloys of nickel, iron and copper (permalloy).
The maximum number of cores can be from 1 to 2 according to the request of customer and according to the required parameters.
All active parts of transformers CTO 15 are compound-insulated with epoxy-mixture resistant to the external effects (UV radiation, humidity, etc.). This material performs both the electrical insulating and the mechanical functions.
The mounting position of transformers is vertical. Transformers are fixed by the means of four screws M12 in the holes in the basic frame. Primary terminals of transformers are equipped with screws M12. We recommend use terminal ends corresponding to the used cross-section of the conductor for attaching to the secondary outlets. The secondary terminal plate is equipped with the waterproof cover. The cover can be sealed. Inside, there is the set with jumpers and small screws for the possibility of earth connection and short circuiting of the wiring. (See “The Instructions for the mounting and operation”.)
In cases where the substitution for the older types of transformers (various producers) is required, we supply transformers CTO 15 with modified basic plates that have identical mounting spacing to spacing of the substituted types.
Current instrument transformers CTO 15 complied all the tests according to the IEC 61869-1, IEC 61869-2, GOST 1516.3-96, GOST 7746-2001.
As a part of customer service we may arrange an official calibration of the transformers carried out by official calibration bodies, including the issue of corresponding calibration protocols.
In agreement with the customer the parameters of the transformer may be modified according to the client´s particular wishes.
Parameters
- Highest voltage for equipment: 24/25 kV
- Power frequency test voltage: 50 kV
- Lightning impulse test voltage: 125 kV
- Nominal primary current: 5–600 A
- Nominal secondary current: 5 A or 1 A
- Rated short-time thermal current, Ith: max 31.5 kA/1s
- Rated dynamic current, ldyn: max 80 kA
- Rated continuous thermal current, Icth: 120 % In
- Accuracy class – measurement: 0.2S, 0.2, 0.5S, 0.5, 1, 3
- Overcurrent factor – measurement: FS 5, FS 10
- Accuracy class – protection: 5P, 10P, PX
- Overcurrent factor – protection: 5, 10, 15, 20, 25, 30
- Nominal power: 5–60 VA
- Nominal frequency: 50 Hz
- Length creepage: 650mm
- Weight: 26 kg
- Thermal insulation class: E
- Operation conditions: corresponds to temperature class -40/40 according to IEC 61869-1
- Standard: IEC 61869-1, IEC 61869-2, GOST 1516.3-96, GOST 7746-2001
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