Document ID: chunk:federal_register_of_legislation:F2023L01529:body:0:p31
Version: federal_register_of_legislation:F2023L01529
Segment Type: other
Provision Reference: 
Character Range: 86533–89648

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 (Vb, Figure 1) is recorded. Vb 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 (V1) 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 (V2) between the positive pole of the tested-device and the ground connection (Figure 1).

       1.2.3.4. Fourth step

        If V1 is greater than or equal to V2, insert a standard known resistance (Ro) between the negative pole of the tested-device and the ground connection. With Ro installed, measure the voltage (V1') 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*(Vb/V1' – Vb/V1) or Ri = Ro*Vb*(1/V1' – 1/V1)

        Figure 2

        If V2 is greater than V1, insert a standard known resistance (Ro) between the positive pole of the tested-device and the ground connection. With Ro installed, measure the voltage (V2') 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*(Vb/V2' – Vb/V2) or Ri = Ro*Vb*(1/V2' – 1/V2)

       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 1: 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