Description

DEIF Multi-Differential Relay MDR-2

DEIF Multi-Differential Relay In order to protect generators from internal short circuits (leaking currents), the MDR-2 is a cutting-edge combination differential protection and short-circuit protection relay.

The MDR-2 provides an adjustable tripping characteristic function that corrects for uneven current readings, preventing fail trippings even in fail-tripping situations.

Direct access to all meetings and a chronological log of up to 150 past events/alarms are both provided by the MDR-2. All computed and measured values are displayed on the unit’s integrated LCD screen, which eliminates the need for additional meters or wiring and makes fault-finding during commissioning easier by pointing out where faults are.

A block (generator + step-up transformer) protection option as well as a short-circuit and over-current protection option are both available.

DEIF Multi-Differential Relay MDR-2

Application
The MDR-2 differential protection relay is a microprocessor-based control unit containing all necessary
functions for monitoring of the differential currents for a synchronous/asynchronous generator or motor (the object).
Via current transformers the MDR-2 measures each phase current on both sides of the object. The current transformers determine the limits of the protection area.
Any failure within these limits (2- or 3-phase short circuits or earth leaks) will be detected as an error Id: Differential currents, the currents flowing through the
two current transformers of the phase in question differ, and, if a preset limit value is exceeded, a warning will be given or a tripping signal transmitted.
The MDR-2 dynamic compensation curves for warning and tripping are defined by the user.
Should an error occur outside the limits of the protection area, the MDR-2 will not transmit a tripping signal, as the above-mentioned phase currents are equal. In
that way a selective protection is achieved.
Except for external measuring transformers the MDR-2 contains all necessary measuring circuits and presents all values on an LC display. Values and messages are presented in clear text (measuring values in engineering units).
The MDR-2 is a flexible and menu/PC-programmed unit, enabling the user to easily adapt the unit to the object in question. The programming procedures are password protected.
Standard functions
The unit is designed for differential current protection of a 3-phase generator/motor.
Inputs and outputs:
Inputs: – 6 currents via current transformers – 2 binary control inputs
Outputs: – 6 relay outputs (“SYSTEM OK”, 5 configurable relays)
Generator protective functions:- Differential current (3-phase) protection, with programmable dynamic compensation (pickup curves)
– Warning: Programmable value and delay
– Trip: Programmable value and delay