RNTA device - what is it?What does the abbreviation RNTA incomprehensible to the ordinary man in the street mean? What is this device and how should it be handled? What are its main technical characteristics?

Answers to all these questions will be provided in this article. Perhaps the information that will be given below will help the specialists to get the information they need about the device they are interested in using the RNTA Y-35 / 125X1 as an example.


  • 1 A device designed to regulate the voltage type РНТА Y-35 / 125X1
  • 2 The structure of the symbol RNTA Y-35 / 125X1
  • 3 terms of Use
  • 4 Specifications
  • 5 Principle of operation
  • 6 Adjustment РНТА Y-35 / 125X1

A device designed to regulate the voltage type РНТА Y-35 / 125X1

How RNTA stands forRNTA type on-load tap-changers have a clear purpose, which is that with their help voltage regulation of transformers is carried out power in the presence of load. Regulation is carried out by the built-in step change of the transformation ratio of power and furnace step-down transformers with a power in the range from 1 to 6.3 kV * A at rated voltage equal to 35kV

In order to make it clearer, you should delve further into the nature of the device name itself. Transformer voltage regulation is essentially a change in the number of windings available. transformer.

The abbreviation RPN means "adjustment under load." This means that this type of switching implies quick switching, which is associated with a constant change in loads. Changing the value of the voltage factor directly to RPN depends on how much power and how much voltage the transformer has. Regulation can be carried out in two ways: automatically and manually when using the control room.

The structure of the symbol RNTA Y-35 / 125X1

You can go to the direct decryption device type RNTA Y-35 / 125X1. This will help to understand the functions of this device.

RNTA Y-35 / 125X1:

  • P - means "regulator";
  • Diagram of the device RNTA Y-35/125 X1H - as you can already guess, the designation of "voltage";
  • T - "three-phase";
  • A - this letter indicates the moment that the device has an active current-limiting resistor;
  • Y - windings are connected by a special scheme - “star”;
  • 35 - indicates the maximum voltage value, expressed in kV;
  • 125 - designation of the nominal current value, which is expressed in A;
  • X1 - performance climatic, as well as the category of accommodation.

terms of Use

The following are the conditions in which this device can operate. This is very important information that gives the user a better understanding of how an existing device works, as well as determine the best conditions for his work.

So, it should be remembered that RNTA Y-35 / 125X1 is able to work in the following conditions:

  • Dimensions RNTA Y-35/125 X1 shown in the diagram.Height above sea level may not exceed 1000 meters;
  • The temperature at which the device is capable of working should be in the following temperature range: from -60 to +50 degrees Celsius;
  • The temperature of the transformer condition can vary from -25 to 100 degrees Celsius, as well as at 60 degrees in the absence of switching.


You should also pay attention to the technical characteristics of РНТА Y-35 / 125X1. In the future, this may help with the operation of the device, as well as better identify the scope of the device.

Technical characteristics РНТА Y-35 / 125X1:

  • RNTA with thermal sensor in the process.The rated voltage of the device can be found by its name. It is 35 kV;
  • The rated current can be equal to 40, 104, 125 A;
  • The maximum value of the switching current is 250 A;
  • The rated voltage of the stage is 0.5 kV;
  • The number of steps is equal to 8 pieces;
  • The device has a limit of mechanical wear resistance, which is equal to 1500000 cycles;
  • There is also a measure of electrical durability at a certain power factor of 0.8. In this case, this indicator is equal to the following number of cycles: 750000;
  • The steady-state fault current is 2.5 kA;
  • The connection of the phases in the device is realized according to the “star” scheme, indicated by the letter “Y”;
  • There is a certain frequency of oil change. The number of cycles after which the oil should be changed is limited to 100,000 cycles.
  • The mass of the entire device is 160 kg. This is an indicator without taking into account the oil contained in the device.

Principle of operation

The RNTA Y-35 / 125X1 device considered in the article is made according to a special principle of load switching. It means that the functions of the contactor and voter are combined in one node, that is, in the contact device. Circuit RNTA is asymmetrical. Such schemes are used in the case of one, strictly defined power flow passing through a transformer.

Adjustment РНТА Y-35 / 125X1

Adjustment RNTA made before commissioning.Before you start working with this device, it is necessary to set it up. it will ensure the correct operation of the switch, and also avoidance of undesirable malfunctions and difficulties with the subsequent operation of the device.

Before adjusting, be sure to carefully check the availability of all necessary components, as well as in correct installation of the drive mechanism in accordance with all specified requirements in the factory documentation. To test the switching mechanism, simply scroll the forward and reverse control knobs on the whole range of regulation. If the mechanism is okay, then the user will be able to switch without making much effort. Switching should be smooth, without any perceived difficulty.

On all branches, the transformation ratio should be measured. This indicator should correspond to the attached factory data.

Pie chart device can be removed at those positions in which carry out their work contacts switch coarse regulation. These are the prescriptions specified in the factory recommendations.

RNTA scheme - how does the device work?A pie chart can be considered satisfactory if coarse regulation contacts work with a tolerance of no more than 20, ranging from -15 to +15 degreesand at the same time the angle of overlap between the operating contacts of coarse and fine regulation cannot be less than 62 degrees.

Also, the user can verify the correct operation of the contacts of the fine control switch, according to the angular diagram, which can be removed in accordance with the principles of removing the pie chart of the device.

The rotation angle is fixed according to the oscillation of the measuring instrument arrow, as well as in the case of the triggering of the marker, which is essentially the indicator instrument arrow. Counting angles is carried out according to the scale of the stationary limb relative to the arrow, which is attached to the rotor shaft.