RTF – (AVR) Automatic Voltage Regulator – IEC 61850

AVR – Automatic voltage regulation for up to 5 power transformers in parallel.

Parallel transformer regulation by master-slave, circulating current and negative reactance methods.

It also includes line voltage drop compensation.

AVR Key Features

  • Voltage Regulation. Maintains the transformer output voltage at the setpoint value, calculating the difference between the measured voltage and the setpoint voltage and comparing it with a threshold level to decide whether to send commands to the tap changer. The first tap change command has a time delay based on an inverse curve or a fixed time. Subsequent commands always have a fixed time delay.
  • Line Voltage Drop Compensation. A compensation based on the measured current and the voltage drop between the transformer and the load, that provides stable voltage under load. The compensation can be calculated by two methods: LDC-Z or LDC-R & X.
  • Parallel Transformers RegulationParallel transformer regulation can be achieved by the following methods:
    • Master / slave
    • Circulating current
    • Negative reactance

The first two methods in the list allow voltage regulation for up to 5 parallel transformers using GOOSE messaging (IEC 61850 ed 1 and 2).

  • Tap Indication and Monitoring.The active tap can be read by digital inputs (directly or in BCD code), by an analog current transducer or by a Resistor Chain. Tap monitoring permits to generate alarms corresponding to irregular or extreme tap positions and to failures after tap change commands.


General characteristics of the “ZIV e-NET flex family” protection relays:

  • Powerful programable logic. 9 2000 event log. Up to 100 oscillography seconds.
  • Alphanumeric or graphic display.
  • 160 DI, 80 DO, and 22 LEDs.
  • Bonding, RSTP, PRP and HSR Redundancy.
  • IEC 61850 Ed.2, DNP3.0, Modbus RTU and PROCOME Protocols.
  • Native process bus. Analog input cards operate as Merging Units for the CPU. Synchronized samples at 4800 Hz (as per IEC 61869-9).
  • Cybersecurity in accordance with IEC 62351, IEC 62443 and IEEE 1686-2013 standards. RBAC, secure keys, physical and logical port disabling, cybersecurity event log, securing of management protocols (PROCOME, HTTPS, SFTP, SSH), remote authentication (LDAP, RADIUS) and digital firmware securitization.
  • Time synchronization by IRIG-B, SNTP and PTP (Ordinary Clock / Transparent Clock).


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