AS ISO 6469.3:2014 – Electrically propelled road vehicles—Safety specifications Part 3: Protection of persons against electric shock
AS ISO 6469.3:2014 – Electrically propelled road vehicles—Safety specifications Part 3: Protection of persons against electric shock.
7.3 Protection under single-failure conditions
7.3.1 Potential equalization
As a general rule, exposed conductive parts of voltage class B electric equipment, including exposed conductive barriorsonclosures, shall be bonded to the electric chassis for potential equalization in accordance with the requirements in 7.9.
7.3.2 isolation resistance
The voltage class B electric circuits intended to be not conductively connected to the grid shall have sufficient isolation resistance in accordance with the requirements in 7.7.
It the minimum Isolation resistance requirement of such circuits cannot be maintained under all operational conditions and over the entire service life, one of me following measures shall be applied:
— monitonrig of the isolation resistance periodically or continuously: an appropriate warning shall be provided if loss of isolation resistance is detected: the voltage class B system may be deactivated depending on the operational state of the vehicle or the ability to activate the voltage class B system may be limited;
double or reinforced insulation instead of basic insulation;
— one or more layers of insulation, barriers andor enclosures in addition to the basic protection:
— rigid barriersenclosures with sufficient mechanical robustness and durability, over the vehicle service lila.
Requirements on isolation resistance for voltage class B electric circuits intended to be oonductively connected to the grid are given in 7.10.2,
NOTE 1 IsolatIon resistances below the required mirmum values can occur due to detenoration of fuel cel fFC) systems’ coolmg llqeds or of certain battery types.
NOTE 2 Coordination between multiple isolation monitoring systems can be necessary, e.g. during charging.
NOTE 3 The dalton resistance Is approximately zero for a voltage class B electric orcuit conductively connected to the grid.
NOTE 4 Additional layer(s) of insulation and double or reinforced insulation include, but are not limited to. those for voltage class B wiring.
NOTE 5 The rigid bamersencloswes irrJe. but are not limited to, power control enclosures, motor housings, connector casings and housings, etc They can be used as single measure instead of basic barriersenclosures to meet both basic and single-failure protection requirements.
7.3.3 CapacitIve couplings
18.104.22.168 Capacitive coilings between a voltage class B potential and electric chassis usually result from V capacitors. used for electromagnetic compatibility (EMC) reasons, or parasitic capacitive couplings.
22.214.171.124 For d.c. body currents caused by discharge of such capacitive couplings when touching d.c. class B voltage, one of me following options shall be fulfilled:
– energy of the total capacitance between any energized voltage class B live part and the electric chassis shall be <0,2 J at its maximum working voltage; total capacitance should be calculated based on designed values of related parts and components: alternative mechanical or electrical measures for d.c. voltage class B electric circuits: see 126.96.36.199. 188.8.131.52 For ac. body currents caused by such capacitive couplings when touching a.c. class B voltage one of the following options shall be fulfilled: ac. body current shall not exceed 5 mA when measured in accordance with IEC 60950-1; alternative mechanical or electflcal measures for a.c. voltage class B electric circuits; see 184.108.40.206. 220.127.116.11 Altemative elecirical or mechanical measures include the following: — double or reinforced insulation instead of basic insulation: — one or more layers of insulation, barriers and/or enclosures in addition to the basic protection: rigid barriers.enckjsures with sufficient mechanical robustness and durability over the vehicle service life, 7.3.4 De-energization The voltage class B electric circuit in question may be de-energized as a protection measure. The monitoring of faults within the circuit or the detection of events may be used to tn9ger the de-energization, One of the following conditions shall be met for the de-energized circuit. The voltage shall be reduced to less than 30 V a.c. (rms) for a.c. circuits and 60 V d.c. for d.c. circuits. — The total stored energy of the circuit shall be <0,2 .J. The transition time to reach the dc-energized state shall be specified by the manufacturer in accordance with expected failures and operating conditions, 7.4 Alternative approach for protection against electric shock As an altemative to 7.3, the vehicle manufacturer shall conduct an appropriate hazard analysis and establish a set of measures which give sufficient protection against electric shock under single-failure conditions. 7.5 Requirements for Insulation If protection Is provided by insulation, the live parts of the electric system shall be totally encapsulated by Insulation that can be removed only by destruction. The insulating material shall be suitable to the maximum working voltage and temperature ratings of the vehicle and Its systems (see also Clause 4). The insulation shall have sufficient capability to withstand the usual voltage. Compliance shall be tested in accordance with 8.3.