MEG-1000 measures and controls the insulation resistance between phase and earth in a neutral insulated or impedance line (IT), with the use of relays. The insulation resistance can be displayed with a galvanometric indicator located on the front of the unit. To carry out the measurements, the unit applies a continuous voltage of 24 V between the phase and earth, measuring the leakage current circulating through the network insulation resistors. This current determines the insulation resistance. The unit has two timed output relays, one acts as the maximum (triggered when the insulation resistance is lower than a determined value). In both relays, the trip point and connection delay time can be adjusted with potentiometers located on the back of the unit. When the insulation resistor is within the maximum and minimum values defined with the potentiometers, the NORMAL LED will be lit on the front panel. When the resistor is out of the margins defined, either exceeding or not reaching the normal levels, the ALARM LED will be lit on the front panel.