• For grounded or non-grounded live networks in land, marine and sub-sea installations

• True r.m.s. measurement not affected by heavily distorted Waveforms
  

• Non-resistive earth current offset function

• Restricted or Unrestricted earth fault detection

• Highest up meter reading on KPM362x, Pathfinder function identifies highest channel

• Analogue output proportional to meter reading (F-version)

Application
The digitally controlled KRM162x (1 channel) monitor flow of earth current between a non-grounded (IT) or grounded TN network and its protective earth. Unit can be used for either Restricted or Unrestricted earth fault detection.

The unit reads the level of earth leakage directly in mA. The standard range is 0-150mA. Larger scale values are available, typically 500mA, 1A, 2A, 5A and 10A.

An AC or DC auxiliary voltage is required for the unit. Start of monitoring function is inhibited when auxiliary power is switched on (default 2secs delay). In this way false tripping during power up, caused by initial charging of network spread capacitance, is avoided.

The meter and the triple-zone status LEDs give at a glance the clear safety message:

• NORMAL

• WARNING

• ALARM

General
RCD MEASURING PRINCIPLE
Ground current is measured by one (KRM162x) IG-transformers (Core Balance Current Transformer (CBCT). The measuring technique is based on the principle that the sum of the phase currents in a fault free circuit is zero. If a ground present, the sum of the phase currents is not zero. This current differential produces a signal from the IG transformer, which is proportional to the earth current. All loaded wires shall go through the CBCT.

OUTPUTS
The unit has C/O relay outputs for Warning and Alarm. The Alarm relays are fail to safety configured. A trip LED flashes when the trip level is passed, the relay trips when the delay has elapsed. The timer resets if the fault is removed during countdown. Offset, trip levels and delays are settable on unit rear.

All F versions have an isolated analogue output proportional to meter reading. If output is used for remote meter reading, we recommend 0-1mA for the slave indicator.

OFFSET FUNCTION
Only the resistive (ohmic) earth leakage current is a measure for the insulation condition between the AC supply and its protective earth. Any reading of leakage current in a fault free network will be caused by the networks spread capacitance. An offset potentiometer on the rear allows normal reactive (capacitive) currents to be ignored.

“PATHFINDER” FUNCTION
The flashing pattern of the Warning or Alarm LED on the KRM362x identifies the highest-up channel producing the trip.