The AS/NZS 4777.1:2024 standard introduces new definitions for supply types, aiming to simplify understanding and application. These big changes clarify how various power systems interact with the grid and manage supply. Here’s a breakdown of the new definitions:
Normal Supply
The “Normal Supply” is the normal grid power controlled through the main switch. It feeds most systems their normal source of electricity in order to ensure a reliable supply under normal conditions.Supplementary Supply
Supplementary supplies complement the normal grid supply and can’t operate in its absence. Whenever the grid power is disconnected, the related inverter shutdowns. These systems complement the grid but rely on the grid for their operation and don’t generate any power of their own.Alternative Supply
Alternative supply systems switch to an alternative source when the grid supply fails and can be implemented by:Changeover Switch
A switch, manual or automatic that changes over between the grid and a back-up generator.Inverter Backup Function
Some inverters have backup ports – normally known as the EPS (Emergency Power Supply) or UPS (Uninterruptible Power Supply).Inlet Plug
Plug for connection to a back-up generator or similar source.Multimode inverters can also operate in both complementary and alternative supply modes. During grid-connected operation, they support the grid, but once the grid fails, they switch to an alternative supply to continue feeding some loads.
Independent Supply
This was previously known as “stand-alone” supply. It is a system where the installation can be completely independent of the grid. The grid may only play a role in terms of charging, and there is no export power to the grid. Such systems would have to comply with the conditions of Appendix M of AS/NZS 4777.2. Part 2 of the new standard provides consistency in terms as used in Part 1 of AS/NZS 4777.1.Substitute Supply
The substitute supplies should be a kind of system which powers only one socket outlet upon an outage in the grid, rated not higher than 15A. Systems like Fronius PV Point already exist for that purpose. It needs to be assured that such systems offer the definition of substitute supply according to the revised standards.These new definitions in AS/NZS 4777.1:2024 aim to reduce confusion and enhance clarity regarding different power supply types. Understanding these distinctions helps in selecting and implementing the right system for various energy needs.
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