Voltage instrument transformers TMNT type


Voltage instrument transformers TMNT type

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

They are designed to be resistant up to 1,2 kV insulation level, molded in epoxy resin under vacuum. The mounting of transformer inside the panel, is realizing through the base metal plate with four screws.

Product catalog and referance price list up to 1,2 kV

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TNMT type voltage transformers are support 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, in cells and low voltage transformer stations, for insulation levels up to 1.2 kV.
The value of the secondary nominal voltages is 100 V, 110 V ,. The accuracy classes of the measuring secondary can also be 0.2, 0.5, 1, 3. For the measuring secondary, the required accuracy class is guaranteed in the range of 25% - 100% of the nominal load.
The operating limit voltage of these transformers is 120% of the rated voltage for continuous operation.
The number of secondary windings is a maximum of one.
The connections to the primary and secondary windings are made on the transformer, these being covered with two sealable covers having provided slots for passing the cables.
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 61869-3.
Metrological verification bulletins can be issued upon request.
For parameters that are not specified in this documentation, we expect you to contact us by e-mail or telephone.

Highest voltage for equipment: 0.72; 1.2 kV

Test with applied voltage 50 Hz - 1 min; 3; 6 kV

Lightning pulse test - 1.2 / 50 µs: -; - kV

Primary rated voltage - One: 230 ÷ 1000 V

Secondary nominal voltage - Us: 100: √3, 100; 110: √3; 110 V

Frequency: 50 Hz

Secondary winding power: 1 ÷ 30 VA

Accuracy class secondary winding measurement: 0.2; 0.5; 1; 3 %

Altitude: maximum 1000 m.

Ambient working temperature: - 5… + 40 ° C.

Storage transport temperature: - 25… + 40 ° C.

Standards: IEC 61869-1: IEC 61869-3

Instructions for connecting voltage transformers to the circuit for measurement,

type TNMT

Measuring voltage transformers, with two insulated (bipolar) TNMT type poles, used in three-phase or single-phase systems for measurement, are supplied with a primary winding marked 0 V-xxx V, and a secondary winding. The secondary windings used are marked with 0 V-xxx V.

When using two bipolar transformers, the installation in the three-phase system is done with the primary and secondary measuring windings connected in an open triangle.

For mounting three bipolar transformers in the three-phase system, the primary and secondary measuring windings must be connected in a closed triangle.

Making connections:

- One of the terminals of the secondary windings “0 V” They will be connected to earth


When using two bipolar isolated transformers connected to the “V” type connection (open triangle), it is mandatory that a terminal at one of the secondary windings of the two transformers be connected to earth. This is required to avoid a short circuit between the two transformers.

Instructions for handling, transport, storage and commissioning

of transformers tension for measurement, TMNT type



Type transformers TNMT 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 TNMT 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 TNMT 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 TNMT, 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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