Current instrument transformers CTPU type


Current instrument transformers CTPU type

The instrument transformers type CTPU, are designed for indoor use in electric distribution panels, for measuring and protection.

They are designed to be resistant up to 0,72 kV insulation level, molded in epoxy resin. The mounting of transformer inside the panel, is realizing through the plastic case with four screws.

Product catalog and referance price list 0,72 kV

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Current transformers for CTPU type measurement are transition type transformers, dry, cast in resin, having the role of both electrical insulation and to ensure mechanical resistance. They are intended for indoor use, for measurement and protection, in cells and substations of medium voltage, for insulation levels from 0.72 kV, the corresponding insulation level for medium voltage being provided by the cables used.

The value of the secondary nominal currents is 5 A or 1 A, there is also the possibility to be combined. The accuracy classes of the measuring secondary can also be 0.2S, 0.2, 0.5S, 0.5, 1, 3, and for the protective secondary they are 5P and 10P. For measuring secondary, the required accuracy class is guaranteed in the range of 25% - 100% of the nominal load, and for protection secondary the accuracy class is guaranteed at 100% of the nominal load.

The working limit current of these transformers is 120% of the rated current. Upon request, the value of this current can be exceeded by an agreement between the manufacturer and the beneficiary, for example 200% of the rated current.

The maximum number of secondary windings is 2, depending on the accuracy class, power and the nominal primary thermal current.

Mandatory, one terminal of each secondary winding must be connected to earth, and unused secondary windings are short-circuited and also connected to ground.

Connections to the secondary windings are made using connection clamps.

The secondary windings are made on magnetic cores with oriented grains, made of different alloys, depending on the accuracy class required.

Transformers can be mounted in any position. The transformers are fixed with the help of four screws in the holes provided in their plastic housing.

The transformers are delivered with all the screws and accessories necessary for the connection in the circuit

Transformers are designed, made and tested according to standards IEC 61869-1, IEC 61869-2.

For parameters that are not specified in this documentation, we expect you to contact us by e-mail or telephone.

Highest voltage for the equipment: 0.72 kV
Test with applied voltage 50 Hz - 1 min; 3 kV
Lightning pulse test - 1.2 / 50 µs: - kV
Primary rated current - In: 50 ÷ 600 A
Secondary rated current - Is: 5 and / or 1 A
Possibility of reconnection in secondary: NO
Frequency: 50 Hz
Thermal current - Ith: max. 200 x In kA
Dynamic current - Idyn: 2.5 x Ith
Rated thermal current - Icth: 1.2 x In
Secondary winding power: 1 ÷ 10 VA
Accuracy class secondary winding measurement: 0.2S; 0.2; 0.5S; 0.5; 1; 3 %
Security factor - FS: 5; 10
Accuracy class secondary winding protection: 5P; 10P
Accuracy limit factor - ALF: 5; 10; 15
Insulation class: B
Altitude: maximum 1000 m.
Ambient working temperature: - 5… + 40 ° C.
Storage transport temperature: - 25… + 40 ° C.
Standards: IEC 61869-1: IEC 61869-2

Instructions for connecting circuit current transformers for measurement,

type CTPU


Current transformers for measuring type CTPU, executed and supplied with one or more secondary windings (1S1-1S2, 2S1-2S2).

Terminals “S2” of all secondary windings, must be connected to ground.

Attention! The product is delivered with secondary windings with shorted start and end terminals.

When only one secondary winding is used, but the second secondary winding is not used in the load, the start and end terminals of the unused secondary winding must be short-circuited and connected to ground. When it is desired to use the secondary in this situation, the starting terminal of the winding must be disconnected from the ground, following the diagram below.

Instructions for handling, transport, storage and commissioning

of current transformers for measurement, type CTPU



Type transformers CTPU they are not heavy objects in relation to their volume. Therefore, the handling and transportation of such products does not require special measures and can not cause injuries to the body of the maneuverer of any kind. The rules of labor protection regarding the handling of objects will be observed. Direct contact with the ground of the transformers will be avoided, especially in conditions of high humidity.



Transportation of type transformers CTPU it will be done in normal atmospheric conditions, avoiding contact with atmospheric precipitation and following the special specifications ("avoid rain", "attention to fragile object", "no overlaying", etc.) marked by a label on transformer package, where applicable.


Storage conditions:

Storage of type transformers CTPU it will be done in closed spaces with environments free of humidity, highly corrosive substances, chemically active substances, flammable or explosive vapors and without electrically conductive dusts.


Putting into service:

At the time of commissioning of the type transformers CTPU, their location in a space that respects the ambient temperature level will be considered in order to be included in the insulation class in which they were made, elements that are specified on the product label.

When commissioning, the corresponding circuit connection must be observed, in accordance with the markings on the transformer terminals and the connection instructions for these types of transformers. Only multi-wire (striped) cables, the section of which corresponds to the rated current specified on the product label, shall be used in electrically sized slippers.

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