Transformer Automatic Voltage Regulator
ARN-T 9 is freely programmable device which by: light indicators on front panel, LCD display and set of relay outputs monitors and regulates the voltage on transformer terminals. The controlled voltage value is measured by the voltage transformer of rated secondary value 100 V AC. The device compares the voltage value to expected value. The value of primary voltage is also presented on the display. The device supervises number of tap changer posistion by binary inputs. The tap changer position can be coded in BCD, binary or Gray code. Tap changer posistion as well as the voltage value are constantly sent to the supervision system. The tap changer is controlled by use of independent relay contacts. The position of tap changer can be coded in BCD, binary or Gray code and sent to other devices of the other value of the control voltage. There is also set of logical nodes to which any pair of contacts can be assigned. Example signals are: minimum and maximum position of tap changer or alarm of close to position close to maximum or minimum. The device offers also functionality of blocking by maximum or minimum voltage, overcurrent, tap changer motor overload. Lack of auxilliary voltage is indicated by the AL contact. All signals can be grouped as ALARM or Failure signals. 7 inch touch screen allows to monitor the operation of the device, preview of inputs and outputs, change the language, preview of real time, preview the event recorder data, preview the analog values.

Manuals, diagrams, technical details


Product description

ARN-T automation device is dedicated to be installed on unmanned substations for power transformer tap changer control purposes. If the voltage on MV side of transformer exceeds set limit, the regulator sends the command to tap changer after set time delay. The time characteristic is voltage dependend. If the exceeding of the voltage limit is higher – the shorter time of tap change runs until the command is sent. There are 5 possible time characteristic to be chosen by the user. Time charactestic can be set independaly for upper and down voltage exceeds. ARN-T is ready to control 2-windigs or 3-windings transformer. ARN-T can also regulate the voltage with auto-compensation of the voltage drop on feeding line. In that case, the stabilised voltage is the voltage in the point of supply. Indication of failures provides the crucial information in quick and precise way. The device provides also the event recorder functionalitty. Data stored in the event recorder can be transferred to the supervision system by fiber-optic link, RS485 or Ethernet connection. Available communication protocols are: ZEG, IEC60870-5-103 and optionally MODBUS, DNP-3 or IEC61850.

Main features:

cassette enclosure of dimensions 19’’/4U/160

  • programmable touch screen 7’’ which allows to control and change the settings
  • 32 programmable RGB LED diodes
  • detachable front panel allowing to be installed in any place
  • programmable insulated binary inputs
  • relay contacts to control the tap changer and indicate failures – programmable
  • insulated measuring inputs: 2 x voltage and 2 x current
  • ALARM relay contact to indicate lack of auxilliary voltage or power supply failure
  • two independent fully redundant power supplies
  • regulation in day, week, month or year intervals
  • voltage dependent time of regulation (5 characteristics)
  • in/out modules equipped with 16-pin screw terminals
  • multiprocessor based decision making system
  • possibility to upgrade by extra functionalities
  • possibility to block signalling with “Alarm ON/OFF” button
  • „Alarm C” button to confirm signalling
  • function buttons F1-F6 for settings bank change
  • 8 communication ports of multiple types: RS232, RS485, ST-fiber-optic
  • software-chosen communication protocol: IEC60870-5-103/ZEG


Rated supply voltage 110-230V DC/AC
or other on request
Burden in power supply <30VA
Number of binary inputs 29
Burden in binary inputs 0,3W/input
Insulation optical
Number of 4U cassettes 1
Input control voltage

220V DC/AC

or other value on request

Settable time delay of voltage regulation 0-25 min
Time resolution 1ms
Communication channels

fiber-optic ST/IEC 870-5-103




Weight 5 kg
Ambient temperature -5÷40 °C

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