The prime purpose of the digitally controlled KCM26x is basically identical to the "traditional" KCM16x Insulation Guard range. An auxiliary Measuring Input Loop Continuity Monitoring Facility has been added to notify the operator if a measuring loop disruption may cause the meter to read a too high insulation level.

An AC or DC auxiliary voltage is required for the unit, if powered from a separate source the network can also be monitored during standby conditions.

The unit has C/O relay outputs for Warning, Alarm and loop failure. The Alarm relay is 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.

Only ONE KCM26x can be connected to each IT-system. The ohmmeter and the triple-zone status LEDs give at a glance the clear safety message:

• ALARM
• WARNING
• HEALTHY

IDV MEASURING PRINCIPLE
Insulation is measured between the complete galvanically interconnected AC network and its protective earth. The signal flows to ground via the path of the insulation fault, the level of flow indicates the insulation resistance. The measuring accuracy is not influenced by any normal kind of load attached to the AC network, the processing time for KCM26x is approximately 400mS.

MEASURING LOOP ALARM
A sensing resistor is mounted at the furthest end of the monitored loop in a separate Loop Resistance Sensor Module (LRSM-1,4 or LRSM-5). There are no restrictions on distance from the sensing resistor to the KPM26x unit. There is a fixed delay of 60 seconds on the loop failure alarm.

The Loop alarm will notify the operator by activating LED LOOP FAILURE and trip relay 3. A disruption in the input measuring loop may cause the guard to falsely read a too high insulation level. The Measuring Input Loop Continuity Monitoring Facility is of special importance during lasting standby conditions (motors, lanterns etc).
MEGGER SAFE
When auxiliary power is OFF the unit input is automatically protected against "megger" test voltages up to 1.4kVDC, and incorrect measurements caused by the unit’s input impedance is avoided.

OUTPUTS
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.

SAFETY
When a voltage adapter (CHx) is used the signal to terminals 4 and 6 on KCM261x and KCM263x is limited to a safe level, avoiding any dangerous voltage exposure to personnel.