IEC 61557-9 Electrical Safety in Low Voltage Distribution Systems Between 1000V AC and 1500V DC - Part 9: Hardware for Insulation Fault Location in IT Systems

EUROLAB laboratory provides testing and compliance service within the scope of IEC 61557-9 standard. This part of the IEC 61557 standard also specifies requirements for insulation fault detection systems that localize insulation faults in any part of the system in ungrounded IT ac systems and ungrounded IT ac systems with galvanically connected dc circuits with rated voltages up to 1000V AC. As with ungrounded IT DC systems with voltages up to 1500 V DC, it must be independent of the measuring principle.

Insulation fault location equipment must be able to localize symmetrical and asymmetrical insulation faults in an IT system and provide a location warning if the insulation resistance in a portion of the installation falls below the response sensitivity.

If the insulation fault location equipment has a self-test function, the self-test should not generate an insulation fault in grounding.

Mandatory Functions Provided by IFLS

An IFLS should include a visual warning device that indicates whether an insulation fault has been detected or permits connection to such a device to indicate a fault. If externally connectable audio signal devices are provided, they can be fitted with a reset feature. In this case, an audible signal will be given when a new fault occurs after a fault is cleared or the device is reset. Location alert will be either local location alert or remote location alert or both.

Local Location Alert (LLW)

This function aims to give a warning signal when the insulation resistance between the system and ground falls below the response sensitivity. This function will include the localization of an insulation fault in an IT system, including symmetric and asymmetric isolation faults, an evaluation of this fault, and a local warning. A local warning must be made by visual indications or audible signals produced by the product that implements the function. Usually this functionality is provided by IFLS.

Remote Location Alert (RLW)

This function aims to give a remote warning signal if the insulation resistance between the system and ground falls below the response sensitivity. This functionality will include the localization of an insulation fault in an IT system, including symmetric and asymmetric isolation faults, an evaluation of this fault, and a remote warning. A relay contact output or electronic switching output or a data communication can be used to remotely signal the warning. The warning output can also be used for switching in some applications.

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