FAQ The alarm threshold of IM400 is set to 1Kohm, why the alarm dropout at more than 1.2-1.3Kohm?
With IM10/20 range and IM400 range an hysteresis principle is apply with threshold alarm and prealarm levels
the principle is :
alarm is activated when default is at the threshold value; alarm is desactivated when default is 20% higher than threshold value. This is to avoid on/off alarm switching when a default is closed to the threshold