What are Central Protection Units and why do you need to know about them?

Did you know that in April 2017 the current converter standard, AS4777.1:2016 changed? It now mandates that commercial PV systems over 30 kVA use Central Protection Units. This is due to the high level of distributed grid connect PV systems, and a concern for safety risks posed by these systems.

What is a Central Protection Unit?

A Central Protection Unit is a device which provides protection functions for inverters and the grid. Outside of the inverter’s in-built protection. They will:

  • Minimise the impacts of fluctuations in voltage, frequency and other parameters on the electrical grid
  • Help prevent damage to the PV system caused by grid fluctuations
  • Ensure a safe, balanced distribution network
  • Maintain reliability of the grid
  • Help the grid with increased penetration of distributed generation systems.

Central Protection is therefore essential for most commercial PV systems over 30 kVA for compliance with both AS/NZS 4777.1 :2016 and the requirements set by the Distribution Network Service Providers (DNSPs).

When do you need a Central Protection Unit?

The Standard specifies central protection as a requirement for systems with a capacity above 30 kVA capacity on a 3-phase network. The local DNSPs may have their own system size limits as per their specific network conditions. This is generally intimated to the system designer at the time of application to connect.

Need help?

If you want to know more about them give us a call and we can help you out. We engineer, design, manufacture, commission and program control systems for renewable energy power generation projects, especially commercial solar PV. It is part of what we do.