18 Dielectric Voltage Withstand Tes

18 Dielectric Voltage Withstand Test18.1 This test is an evaluation of the electrical spacings and insulation at hazardous voltage circuits within the electric energy storage system.18.2 Circuits exceeding 42.4 V peak or 60 Vdc shall be subjected to an electric strength test in accordance with the Standard for Information Technology Equipment Safety – Part 1: GeneralRequirements, UL 60950-1, Clause 5.2.Exception: Semiconductors or similar electronic components liable to be damaged by application of the test voltage may be bypassed or disconnected.18.3 The test voltage is to be applied between the hazardous voltage circuits of the DUT and non-current carrying conductive parts that may be accessible.18.4 The test voltage is also to be applied between the hazardous voltage charging circuit and the enclosure/accessible non-current carrying conductive parts of the DUT.18.5 If the accessible parts of the DUT are covered with insulating material that may become live in the event of an insulation fault, then the test voltages are applied between each of the live parts and metal foil in contact with the accessible parts.18.6 The test voltages shall be applied for a minimum of 1 min with the cells/modules disconnected to prevent charging during application of the voltage. Technologies that are required to be at an elevated operating temperature in order to be active, such as sodium-beta chemistries, shall be in a hot state prior to disconnection and applying the test potential.18.7 There shall be no evidence of a dielectric breakdown (breakdown of insulation resulting in a short through insulation/arcing over electrical spacings) as evidenced by an appropriate signal from the dielectric withstand test equipment as a result of the applied test voltage. Corona discharge or a single momentary discharge is not regarded as an dielectric breakdown (i.e. insulation breakdown).18.8 If the EESS contains hygroscopic materials that may affect spacings, this test is repeated with the DUT or with the subassembly of the DUT containing the hygroscopic materials subjected to humidity conditioning of the Standard for Information Technology Equipment Safety – Part 1: General Requirements, UL 60950-1, Clause 2.9.2. As a result of this testing, there shall be no dielectric breakdown as outlined in 18.7.