Why use Mains protection?
With an increase in decentralised energy sources such as Diesel Generator Sets, Photovoltaic plants and other alternative sources, the distribution system becomes less stable. It becomes more common to see fluctuations in frequency, voltage and other parameters. To minimise the impact and disturbances to the electrical network it is essential that all Energy sources over a certain size (in most of Australia over 30kW) have mains protection.
When making an application to connect (if your system is above 30kW three phases or 10kW single phase) the Distribution Network Service Provider (DNSP) will insist on secondary protection to be provided. This will be in addition to the in built protection offered by AS4777 compliant inverters. They will insist that the protection relay shall be certified to IEC 60255, G59 or other product standards.