METHOD FOR MEASURING INSULATION RESISTANCE AT DIRECT CURRENT CIRCUITS UNDER OPERATING VOLTAGE AND DEVICE FOR ITS IMPLEMENTATION Russian patent published in 2013 - IPC G01R27/18 

FIELD: measurement equipment.

SUBSTANCE: measuring loop is connected between one of the poles of the controlled circuit and an earth bus, the loop comprises a regulated addtional DC source forming unipolar two-stage voltage; in order to decrease measuring voltage of the additional source a pole of the additional source which is like the connected pole of the controlled circuit is connected to the earth circuit. The device comprises a measuring loop connected between one of the poles of the controlled circuit and the earth bus and consisting of a regulated additional DC source, limiting resistors and a current shunt, it also includes a microprocessor element, a precision element to regulate supply voltage at the analogous part of the microprocessor element, a unit to transfer the measurement data; herewith a circuit of zoom operational amplifiers connected in series is connected parallel to the current shunt, one more operational amplifier with input voltage divider is connected parallel to the additional source, outputs of the operational amplifiers are connected to the inputs of analogous-digital conversion of the microprocessor element, and the microprocessor element output regulating the additional source has the function of pulse-duration modulation.

EFFECT: improvement of accuracy and credibility of measurements.

2 cl, 1 dwg