New Earth Leakage Relay DER3B series

The DER3B, differential relay with separate toroid our is a protective device that determines, by using actuators such as coils shunt or undervoltage release, the interruption of the power line if it detects a leakage current to ground type AC, AC pulsating or continuous higher than set threshold.

They can be used on LV networks up to 1000V DC (with a pole to ground), AC (type TT, TN) or mixed.

Choose the adequate protection for your plant is an essential element at security purposes. In this perspective, every designer and installer must be particularly careful in choosing and then implementing the necessary measures to give more efficiency to the protection against indirect contact of machines and installations.

Reference Standards

The DER3B, fully comply with regulations in force CEI EN 60947-2:2007 Annex M 8 edition (extract of the Official Journal of the European Union, publication of titles and references of harmonized standards under the Directive 2008 / c 28/01).

This last, imposed by legislator, has normative standards very strict in order to achieve greater safety in the installations, avoiding the dangers arising from indirect contacts of installations and machinery.

The respect of the standards in question is a mandatory element in the choice to be made for a correct design and application of the differential protection.

Features :

- Reading of current TRMS

- High immunity to disturbances and the consequent reduction of untimely tripping

- Wide range of auxiliary power supply (48 to 400 VAC or 24 to 240 VDC)

- LCD dot matrix able to change color to ease use (green : supervision, light blue: set-up, red : alarm)

- Intuitive set-up

- Display and storage of the maximum current intervention

- Display of diagnostic messages

- Continuous monitoring of the correct operation of the coil opening or minimum voltage coil

- Continuous monitoring of the connection with the toroidal transducers to ensure the protection

- Large selectivity adjustment of current intervention threshold

- Large selectivity adjustment of intervention delay

- 2 thresholds with 2 output contacts (250V 5A)

- Standard serial output RS485 ModBus RTU.

- Ease interfacing with datalogger Dossena model Multilog-Eth, without dedicated software is able to historicize parameters, measurements and events.

Application Tips

The differential relays type DER3B, since recognize any DC component of the fault current, are recommended for use in lines with Inverter, UPS, machine tools, three phase frequency converters, PV systems, lifts, testing equipment in laboratories, means of production at construction sites, battery charging stations for forklift trucks, cranes, welding machines or arched, lathes, milling machines, etc..

Installation Tips

The correct application of the protection device requires the installation of 2 separate toroidal transducers for each differential relay DER3B.

- toroid type D to measure the differential currents of alternate type and alternate pulsating (D series for Class A / AC).

- toroid type B to measure the differential currents of continuous type (series B for Class B).

The toroidal current transducers must be installed upstream the lines or loads to be protected and monitored. Inside the transducer must pass all the conductors (phases and neutral if distributed) of single and three phase lines. In case of you decide to use homopolar protection to earth is necessary pass only the earth conductor.

It is important centre the cables in the toroidal transducer. Choose the toroidal transducer according to the characteristics of the rated current / permissible, also the diameter is about 2 times larger than the diameter of the cables.

Concern the connection between differential DER3B and toroidal transducers, it is recommended to use twisted and / or shielded conductors. These have to pass as far away possible from the power cables to avoid interference problems. We recommend using a minimum diameter of 1 mm² for distances of less than 20m and 2.5 mm ² for longer distances.