Document ID: chunk:federal_register_of_legislation:F2023L01526:body:0:p40
Version: federal_register_of_legislation:F2023L01526
Segment Type: other
Provision Reference: 
Character Range: 113271–116360

carried out, such as removal of the cover in order to reach the live parts, drawing of measurement lines, change in software, etc.

        In cases where the measured values are not stable due to the operation of the isolation resistance monitoring system, necessary modification for conducting the measurement may be carried out by stopping the operation of the device concerned or removing it. Furthermore, when the device is removed, a set of drawings will be used to prove that the isolation resistance between the live parts and the ground connection designated by the manufacturer as a point to be connected to the electrical chassis when installed on the vehicle remains unchanged.

        These modifications shall not influence the test results.

        Utmost care shall be exercised as to short circuit and electric shock, since this confirmation might require direct operations of the high-voltage circuit.

       1.1. Measurement method using DC voltage from external sources

       1.1.1. Measurement instrument

        An isolation resistance test instrument capable of applying a DC voltage higher than the nominal voltage of the Tested-Device shall be used.

       1.1.2. Measurement method

        An insulation resistance test instrument shall be connected between the live parts and the ground connection. Then, the isolation resistance shall be measured.

        If the system has several voltage ranges (e.g. because of boost converter) in a galvanically connected circuit and some of the components cannot withstand the working voltage of the entire circuit, the isolation resistance between those components and the ground connection can be measured separately by applying at least half of their own working voltage with those component disconnected.

       1.2. Measurement method using the Tested-Device as DC voltage source

       1.2.1. Test conditions

        The voltage level of the Tested-Device throughout the test shall be at least the nominal operating voltage of the Tested-Device.

       1.2.2. Measurement instrument

        The voltmeter used in this test shall measure DC values and shall have an internal resistance of at least 10 MΩ.

       1.2.3. Measurement method

       1.2.3.1. First step

        The voltage is measured as shown in Figure 1 and the operating voltage of the Tested-Device (Ub, Figure 1) is recorded. Ub shall be equal to or greater than the nominal operating voltage of the Tested-Device.

    Figure 1

       1.2.3.2. Second step

        Measure and record the voltage (U1) between the negative pole of the Tested-Device and the ground connection (Figure 1).

       1.2.3.3. Third step

        Measure and record the voltage (U2) between the positive pole of the Tested-Device and the ground connection (Figure 1).

        Fourth step

        If U1 is greater than or equal to U2, insert a standard known resistance (Ro) between the negative pole of the Tested-Device and the ground connection. With Ro installed, measure the voltage (U1') between the negative pole of the Tested-Device and the