ISO 6469-3-2021 pdf free download – Electrically propelled road vehicles — Safety specifications — Part 3: Electrical safety.
An electric circuit may consist of sections with voltage class B1 and sections with voltage class A.Inthis case the following conditions shall apply.
– At a single fault in this circuit the voltage of the voltage class A sections shall not exceed the limits
specified for voltage class A.
— The voltage class A sections shall be classified as voltage class A.NOTE A failure of an electronic switch is an example for a single fault.6.1.3 General requirements for voltage class B2
Protection against electric shock for voltage class B2 shall be comprising:-provisions for basic protection according to 6.2; and
– provisions for fault protection according to 6.3.
The provisions for protection shall meet the requirements as described in 6.2.and 6.3.Provisions for fault protection shall include 6.3.1,6.3.2 and 6.3.3.
6.2 Basic protection
For basic protection, the requirement of basic insulation shall be fulfilled.The protective provisions in 6.4 shall apply.
Different measures to provide basic protection may be used for different sections of a circuit.
6.3 Fault protection and additional measures
6.3.1 Equipotential bonding
Exposed conductive parts of voltage class B electric equipment that can be touched by a test fingeraccording to IPXXB(see ISo 20653) after removing all other parts that can be removed without usingtools,shall be bonded to the electric chassis to achieve equipotentiality.
All components forming the equipotential bonding current path shall withstand the maximum currentit will be exposed to in the event of a single insulation fault between a voltage class B live part and anexposed conductive part or between a voltage class B live part and the equipotential bonding currentpath.
lf de-energization in case of such a single insulation fault is not implemented, provisions shall be takento avoid risk of harmful electric shock in the event of two insulation faults, each between a voltage classB live part and an exposed conductive part or between a voltage class B live part and the equipotentialbonding current path, existing simultaneously.
NOTE1 The fault current originated from an insulated voltage class B electric circuit (i.e. a voltage class B2electric circuit or a voltage class B1 electric circuit which is not conductively connected to the electrical chassis)is low in the event of such a fault and de-energization is not imperative.
EXAMPLE1 The equipotential bonding current path is designed to withstand a short-circuit current until de-energization is achieved.
EXAMPLE2 The isolation monitoring according to 6.3.2.2 is used to deactivate and de-energize (see6.3.4) thevoltage class B2 system depending on the operational state of the vehicle and the ability to activate the voltageclass B2 system is limited if the minimum isolation resistance requirement is violated.
NOTE2 Currents caused by electromagnetic interference (EMI) and currents from voltage class A and voltageclass B1 systems using the equipotential bonding path as a conductor contribute to the maximum currentthrough the equipotential bonding current path.
The resistance of the equipotential bonding path between any two of these exposed conductive partsof the voltage class B electric circuit that can be touched simultaneously by a person shall not exceed0,1Q2.
Conformance shall be tested in accordance with 10.2.
NOTE3 Parts that are separated by a distance of more than 2,5 m are normally considered not to besimultaneously accessible.
NOTE4 A physical barriers is a means that can prevent simultaneous access to exposed conductive parts.
6.3.2 lsolation resistance
6.3.2.1 General
The voltage class B2 electric circuits shall have sufficient isolation resistance.
The isolation resistance, divided by the maximum working voltage, shall have a minimum value of100 Q/V for DC circuits and a minimum value of 500 Q/V for AC circuits.ISO 6469-3 pdf download.