Overcurrent protection with four independent stages
Each stage can be switched ON or OFF

The type of each stage can be:
Definite time delay or Instantaneous overcurrent protection - ANSI 50/51/67
Inverse time delay overcurrent protection - ANSI 51/67TOC with selectable time delay characteristic according to IEC and ANSI standards

Directional or non-directional overcurrent protection stages:
All stages may be set independently from each other for directional or non-directional and combined according to the user's requirements
The maximum sensitivity angle can be configured for
overcurrent protection function in step 1°
Possibility for non-directional relays after remote or manual circuit breaker (CB) closing

Acceleration of overcurrent protection stages:
Possibilities for acceleration from Autoreclosing depending of the cycle
Possibilities for acceleration after remote or manual CB closing

Blocking:
Possibility for block or enable the action of the current elements of each stage separatelly, depending on pick-up of the under voltage relays of the respective phases of the Under voltage protection (UVP)
Possibilities for blocking of each stage separately from an external signal received by dedicated binary inputs
Possibilities for blocking of each stage separately at the different reclosing cycles of the Autoreclosing function
Possibilities for blocking the AR at the trip of each stage.

Overcurrent ground (earth) fault protection with three independent definite time delay stages - ANSI 50N / 51N / 67N;
Each stage can be switched ON or OFF

Directional or non-directional overcurrent earth fault protection stages
All stages may be set independently from each other “directional” or “non-directional” and combined according to the user's requirements
The maximum sensitivity angle can be configured for overcurrent ground fault protection in step 1 °
Possibility for non-directional relays after remote or manual circuit breaker (CB) closing

Acceleration of overcurrent ground fault protection stages
Possibilities for acceleration from Autoreclosing depending of the cycle
Possibilities for acceleration after remote or manual CB closing

Blocking
Possibilities for blocking of each stage separately from an external signal received by dedicated binary inputs.
Possibilities for blocking of each stage at the different reclosing cycles of the Autoreclosing function
Possibilities for blocking the AR at the trip of each stage

Inverse time delay overcurrent ground (earth) fault protection - according to ANSI;

51N/67N TOC with selectable time delay characteristic according to IEC and ANSI standards;

Directional or non-directional inverse time overcurrent ground fault protection:
The maximum sensitivity angle can be configured for both functions – the same max. sensitivity angle for inverse time and definite time ground fault protections
Possibility for non-directional relays after remote or manual circuit breaker (CB) closing

Blocking:
Possibilities for blocking of the ITGF from an external signal received by dedicated binary input;
Possibilities for blocking at the different reclosing cycles of the Autoreclosing function
Possibilities for blocking the AR at the trip of the ITGF

Evaluation of negative sequence component of the currents – ANSI 46;
In line protection, the negative-sequence protection permits detection on the high side of high-resistance phase-to-phase faults and phase-to-earth faults that are on the low side of a transformer. This provides backup protection for high-resistance faults beyond the transformer. To detect the unbalanced load, the ratio negative-sequence current/rated (nominal) current is evaluated;
A measured current element for the negative sequence current - I₂;
Timer activated at current measuring element pick-ups;
Possibilities for blocking of the NSOC from an external signal received by dedicated binary input.

Uses a thermal model of the line based on its heating and cooling time constants and an exponential law of alteration – ANSI 49;
Monitors the temperature state through the relative temperature which is connected with the squared current of the line;
In case of overload the protection picks-up with a delay which depends on the degree of overload;
The protection has two stages providing trip and pre-trip alarm outputs;
Possibilities for blocking of the TOL from an external signal received by dedicated binary input.

Capacitive power relay for insulated neutral networks or active power relay for compensated networks – ANSI 50Ns/67Ns;
Timer activated at power measuring element operation (pick-up);
Directional or non-directional protection – pick-ups only at positive values of the power (directional PGF) or at absolute values of the power (non-directional PGF);
Possibilities for blocking of the PGF from an external signal received by dedicated binary input.

Under voltage protection with two independent stages;
Selectable phase-to-phase or phase-to-neutral voltage relays – ANSI 27, 27S;
Three measured voltage elements;
Each stage can be switched ON or OFF;
Possibility for UV function blocking at voltages, beyond the setting range;
Possibility for UV function blocking through the dedicated binary input (at operation of instantaneous overcurrent protection or distance protection on 110 kV level for example.

Residual voltage earth fault protection – ANSI 59N;
A measured voltage element for the residual voltage 3Uo;
Timer activated at voltage measuring element pick-ups;
Possibilities for blocking of the NVD function from an external signal received by dedicated binary input.

Over voltage protection with two independent stages – ANSI 59;
Each stage can be switched ON or OFF;
Selectable phase-to-phase or phase-to-neutral voltage relays;
Three measured voltage elements;
Timer activated at voltage measuring element operation (pick-up);
Possibilities for blocking of the OV function from an external signal received by dedicated binary input.

Evaluation of negative sequence component of the voltages – ANSI 47;
A measured voltage element for the negative sequence voltage U2;
Timer activated at voltage measuring element pick-ups;
Possibilities for blocking of the NSOV from an external signal received by dedicated binary input.

Frequency protection with two independent stages;

Each stage can be switched ON or OFF;

The type of each stage can be:
Under frequency protection - ANSI 81U
Over frequency protection – ANSI 81O

The function is blocked when the measured voltages are very low;

Possibilities for blocking of the FP from an external signal received by dedicated binary input.

Autoreclosing function acc. ANSI 79AR;

Up to 6 shots;

Starting condition:
At the circuit breaker and control switch position discrepancy• at the circuit breaker and control switch position discrepancy
At tripping command: from internal protections; from external protections - by binary inputs; from internal or external protections.

The breaker failure protection function monitors the reaction of a circuit breaker to a trip signal from of any integrated (internal) and external protections – ANSI 50BF;

Breaker failure detects the tripping command issued. The tripping command can be issued by follow:
Internal relay protection function (activation of the configured binary outputs for tripping);
External relay protection function (activation of a dedicated binary input);

If after a programmable time delay, the circuit breaker has not opened, breaker failure protection issues a trip signal via a super ordinate circuit breaker.

Trip circuit supervision – ANSI 74TC;
One or two binary inputs can be used for monitoring the circuit-breaker trip coils including the connecting cables.
An alarm signal is issued if the circuit is interrupted.

Visualization of the circuit breaker’s phase life time;
Signalization of CB run out of resource;
Possibility for describing of the CB life time curves;
Possibility for editing the CB’s life time value for each phase;


The RFI 401 device has 4 selectable setting groups including all protection and automation functions. Commutation between the separate groups can be achieved locally, remotely or via dedicated binary inputs.

The device receives processes and archives the following information: :
Change of state of the double-positioned equipment
Alarms from the protection system
Warning alarm for exceeding of limit values
Alarms from external protections and automatics
Alarm at not executed command and at activating of inhibited commands

The information is transferred to the work station PC having it's date and time and it is available on the RFI 401 display.

The device can be connected to Work Station in SCADA-system by means of local network. The network is based on RS485 or fiber optic – the respective interface connector is used. The communication protocol is IEC 60870-5-103 (option IEC 61850). The device’s data acquisition and remote control functions are performed by means of work station – measuring, signaling, remote control (opening or closing command to the circuit breaker, disconnecttors, earthing switch).
Additionally by work station facilities the device can be configured its settings parameters, can be read and corrected and all stored into unit’s memory data can be archived. Also all data stored by means of “Disturbance recorder” and “Event recorder” functions can be transferred and archived into WS for farther analysis.

Device’s HMI interface is situated on the front panel. It consists of:
LCD display – 2 rows, 16 characteristics each. The display has back light illumination (option: graphical monochromatic display)
Indication zone of 9 LED’s (green LED “READY” and 8 red colored S1 – S8 which are free configurable)
Screen blinkers (7 pcs) free configurable
Functional keypad comprising 10 push buttons
PC optic interface zone for positioning of specially designed connection cable

The MMI program is a 32-bit application intended to work under WINDOWS® operational system. The connection between the device and PC running MMI software is done trough RS232 interface by means of specially designed connection cable. The PC interface cable can be connected to PC COM port or to USB port through RS232-USB converter. The connection is fully isolated.
The PC interface cable can be connected to the device in one of two ways: by the serial port CANON 9 type positioned on the left side of the device or by the serial port positioned on the front side of the device (by means of magnet – optical head).
The PC based MMI program is designed to make the configuration and setting of the relay easier. It can fulfill the following functions:
Reviewing, changing, saving and setting of the relay configuration and settings;
Reviewing and saving of information from event recorder and disturbance recorder;
Remote commands such as: changing of the working setting group; synchronizing of the real time clock; LED indicators acknowledgment; clearing of the events stored into the device’s memory; changing the CB life time ect.;
Remote control of the main measuring possibilities of the relay – analogue and binary outputs and LED indicators ;
Analysis and documentation of system faults;
Printing of the setting parameters, configurations, recorded events and distur-bance data saved into the relay memory.

Download MMI program