MRM3

Productomschrijving

The motor protection relay MRM3-2 offers reliable protection for LV and MV motors which are either operated via power contactors or power circuit breakers.

The following functions are integrated into this relay:
• Overload protection acc. to IEC 255-8 in consideration of the initial load factor (thermal image)
• Definite undercurrent protection
• Definite time over current protection (DMT)
• Inverse time over current protection (IMT) with select-able trip characteristics
• Short-circuit protection
• Load unbalance supervision with definite or inverse trip characteristics
• Earth-fault detection with suppression of harmonics

The MRM3-2 recognizes the “Start-Up“ and “Motor Running“ phase. Motors with a limited number of starts can be controlled by the start limiting function of the relay. The earth-fault supervision is either realized in Holm-green connection or by means of a core-type current transformer. The motor can be stopped in delayed or undelayed mode via digital inputs.
The MRM3-2 is available with rated currents of 1A or 5A.

Features
• Microprocessor technology with self-supervision,
• Measuring of phase currents as RMS value,
• Digital filtering of the earth current with discrete Fourier analysis, by which the influence of interference signals, such as harmonics and transient DC components during an earth- fault are suppressed.
• Two sets of parameters,
• Operating hour meter,
• Complies with the requirements of IEC 255-8, VDE435, part 301-1 for overload relays,
• Definite time undercurrent protection,
• Selectable protective functions : Definite time over-current protection (DMT) and inverse time over current protection (IMT)
• Selectable IMT trip characteristics of IEC 255-4:
– Normal inverse (Type A)
– Very inverse (Type B)
– Extremely inverse (Type C)
– Special-purpose characteristics
• Reset mode for DMT/IMT trip characteristics is selectable,
• Definite element for short-circuit high-speed trip
• Single-step earth fault supervision,
• Load unbalance protection with inverse or definite trip characteristics (NPS),
• CB failure protection,
• Display of the measuring values as primary quantities,
• Measuring of the phase currents during short-circuit free operation,
• Blocking of the individual protective elements or the trip elements can be set freely,
• The protective functions can be freely allocated to the output relays. (Relay Matrix),
• Suppression of an LED indication after activation (LED flash),
• „Manual/Automatic“ reset function of the trip elements adjustable via the configuration matrix,
• Saving of trip values and the switch-off times (tCBFP) of 25 fault events (voltage fail-safe)
• Recording of up to 8 fault events with time stamp,
• Display of date and time,
• Trip via digital inputs,
• Rack mounting, with self-acting short-circuit mechanism for CT circuits,
• Possibility of serial data exchange via the RS485 interface, optionally with SEG Electronics RS485 Pro-Open-Data Protocol or Modbus Protocol.