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DC Protection Relays and Transducers for the Railway Industry

T.EL.FER. develops a wide range of multifunctional direct-current (DC) protection relays, and current and voltage transducers for the DC traction market for trains, metros, tramways and trolleybuses.

We also produce low-power, low-voltage, ultra-high insulation DC/DC converters, voltage and current recorders, minimum voltage relays and thermal image relays.

Our products are approved by Rete Ferroviaria Italiana (RFI) and we have a quality system that meets UNI EN ISO 9001: 2008 standards.

DC traction protection relays for railway operations

T.EL.FER’s TF-RP21 high-performance DC protection relay comprises two 32 bit processors and a digital signal processor (DSP), in order to quickly detect failures and effectively protect rail lines.

The optional integrated programmable logic controller (PLC) allows the implementation of customised automatisation functions. The device allows direct fibre-optic connection with our current and voltage transducers.

Our DC protection relay implements a wide range of protection thresholds such as current and voltage levels, overhead line temperatures, maximum current variations, and switchboard or cable earth faults.

The TF-RP21 is also able to record a wide range of values with a one-minute resolution for up to three months, including supplied and input energies, as well as maximum and minimum voltages and currents.

The device can store up to 60 three-second, oscilloperturbographic recordings with a 125-microsecond resolution of both analogue and digital signals, allowing a deep analysis of any event, with an accurate time-relationship between all signals.

The TF-RP21NM can record currents and voltages with resolutions from 1ms to 499ms, or current, voltage and energy levels with resolutions ranging from 500ms to 10s onto a 32GB USB.

Relays for DC traction protection on rail lines

Our TF-RP1X three-analogue channel protection relay is available in several firmware versions to enable several protection function combinations.

All models offer:

  • Measurements of line voltage and current or other relevant parameters
  • Oscillographic event recordings
  • A self-diagnostic, Modbus interface
  • A user-friendly interface
  • An alphanumeric display with two lines of 16 characters to clearly display values and events
  • Capture and visualisation capabilities of oscilloperturbographic recordings
  • A continuous self-test function with remote signalling of malfunctions

DC current / voltage transducers

T.EL.FER’s TF-LP optical fibre transducers and TF-CONV receivers are designed to operate together in order to achieve a compact, affordable and economic measurement system.

They can measure either / both current and voltage levels on 1,500V lines or 3,000V lines. Devices are easily configurable on-site and the large power supply range (from 80VDC to 260VDC, or between 24VDC to 56VDC) makes them simple to install and operate.

TF-CONV receivers convert measurements received from optical fibre to current loop informations and display them on a six-digit high-brightness display.

TF-LP transducers can be connected directly through optical fibre to the TF-RP21 traction protection relays.

High-reliability current and voltage transducers for rail operations

The TF-PROBE I and V transducers feature 16bit resolution and redundant measurement channels with real-time congruency checks for 3,000V lines.

The PROBE-I also offers protection against overvoltage applied on shunt terminals up to 6kV. The transducers have optical fibre output and can be directly connected to a TF-RP21 relay or a TF-CONV receiver.

Thermal image relays for line test resistors

The TF-IT thermal image relay measures the current flowing into a load resistor through a Hall sensor. It also calculates the temperature reached by the resistor and signals when a programmable threshold has been passed.

It features programmable physical characteristics of the resistor and is equipped with an environment temperature sensor.

Ultra-high insulation DC/DC converters for railways

Our TF-UI 0505 DC/DC converter is a new proprietary technology that allows high insulation levels in a small, lightweight device.

Features and capacities include:

  • A 1.7W DC/DC converter
  • Input: between 4.85VDC and 6.5VDC
  • Output: 5VDC +/- 1%
  • Insulation: 25kVAC RMS


Via Soprasasso 8/2
38121 Trento

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