Document ID: chunk:federal_register_of_legislation:F2023L01526:body:0:p41
Version: federal_register_of_legislation:F2023L01526
Segment Type: other
Provision Reference: 
Character Range: 116115–119070

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 ground connection (see Figure 2).

       Calculate the electrical isolation (Ri) according to the following formula:

       Ri = Ro*Ub*(1/U1' – 1/U1)

    Figure 2

        If U2 is greater than U1, insert a standard known resistance (Ro) between the positive pole of the Tested-Device and the ground connection. With Ro installed, measure the voltage (U2') between the positive pole of the Tested-Device and the ground connection (see Figure 3).

        Calculate the electrical isolation (Ri) according to the following formula:

        Ri = Ro*Ub*(1/U2' – 1/U2)

    Figure 3

       1.2.3.5. Fifth step

        The electrical isolation value Ri (in Ω) divided by the nominal voltage of the Tested-Device (in volts) results in the isolation resistance (in Ω/V).

        Note : The standard known resistance Ro (in Ω) should be the value of the minimum required isolation resistance (in Ω/V) multiplied by the nominal voltage of the Tested-Device plus/minus 20 per cent (in V). Ro is not required to be precisely this value since the equations are valid for any Ro; however, a Ro value in this range should provide good resolution for the voltage measurements.

Annex 6

Confirmation method for the function of an on-board isolation resistance monitoring system

       The on-board isolation resistance monitoring system shall be tested using the following procedure:

       (a) Determine the isolation resistance, Ri, of the electric power train with the electrical isolation monitoring system using the procedure outlined Annex 5A.

       (b) If the minimum isolation resistance value required in accordance with paragraphs 5.1.3.1. or 5.1.3.2. is 100 Ω/V, insert a resistor with resistance Ro between either side of the high voltage bus that exhibit lower value in U1 or U2 measured in accordance with paragraph 2.2.3. of Annex 5A and the electrical chassis. The magnitude of the resistor, Ro, shall be such that:

        1/(1/(95xU) – 1/Ri) ≤ Ro < 1/(1/(100xU) – 1/Ri)

        where U is the working voltage of the electric power train.

       (c) If the minimum isolation resistance value required in accordance with paragraphs 5.1.3.1. or 5.1.3.2. is 500 Ω/V, insert a resistor with resistance Ro between either side of the high voltage bus that exhibit lower value in U1 or U2 measured in accordance with paragraph 2.2.3. of Annex 5A and the electrical chassis. The magnitude of the resistor, Ro, shall be such that:

        1/(1/(475xU) – 1/Ri) ≤ Ro < 1/(1/(500xU) – 1/Ri)

        where U is the working voltage of the electric power train.

Annex 7A

Verification method for testing authorities confirming document based isolation resistance compliance of electrical design of