Netz- und Anlagenschutz (NA-Schutz): Funktion, Vorschriften und Bedeutung für Energieanlagen

Grid and Plant Protection (GPP): Function, Regulations, and Importance for Energy Systems

January 28, 2026

The grid and plant protection (NA protection) is a central safety element of modern power generation plants.

It ensures that in the event of disruptions in the public power grid, a plant automatically, quickly and in accordance with standards disconnects from the grid.

For electricians, PV installers, electrical retailers and companies in the energy sector, NA protection is an indispensable component for the successful grid approval by the grid operator.

Why is grid and plant protection indispensable today?

A standard-compliant NA protection ensures that:

There is no reimbursement in the event of grid faults
Maintenance and troubleshooting work can be carried out safely
Damage to the grid infrastructure is avoided
All legal and grid operator requirements are met.

“Without NA protection, grid approval is not possible. NA protection is not a voluntary safety measure, but a mandatory requirement by grid operators to prevent backfeeding in the event of grid failures, enable maintenance work, and avoid personal injury and property damage.”
(Thomas Gregorn, owner of JaunaTronic)

How grid and plant protection works

NA protection operates according to a clearly defined sequence and reacts within fractions of a second:

Monitoring: The protective relay continuously measures the grid voltage and frequency. Special relays monitor the grid parameters directly at the plant's feed-in point.
Detection: In the second step, the deviation is evaluated. Small fluctuations within tolerances → no action. Exceeding limit values → activation of NA protection. Permissible limit ranges: Frequency: 47.5 – 51.5 Hz; Voltage: 80 – 115 % of nominal voltage
Triggering: After a short, standardized time, the protective relay trips the associated coupling switch.
Disconnection: A coupling switch or contactor safely disconnects the plant from the public grid within a maximum of 0.2 seconds. The plant then no longer feeds electricity into the grid and operates in island mode or switches off completely, depending on the configuration.

Requirements for NA protection in Austria

For specialist companies, a correctly designed and tested NA protection is a prerequisite for every successful plant acceptance!

In Austria, the OVE guideline defines central safety requirements for stationary electrical energy storage systems (ESS) that are permanently connected to fixed installations and to the low-voltage grid. It provides clear guidelines for the safe planning, installation, setup and accommodation of storage systems and supplements existing standards where these do not cover certain aspects.

Click here for the OVE Guideline R 25: https://www.austrian-standards.at/de/shop/ove-richtlinie-r-25-2020-03-01~p2514254

Both when drawing electricity and feeding it in, all technical and organizational conditions for grid connection must be met.

From 30 kVA: external central NA protection required
Smaller systems: often integrated protection in the inverter

NA protection is justified for:

Photovoltaic systems
Combined heat and power plants
Wind power plants
Hydropower plants

Important factors when choosing NA protection

Fail-safe principle: NA protection must trip immediately in the event of auxiliary voltage failure. This is achieved through a two-channel design, integrated self-monitoring, and continuous function control.
Coupling switch – safe grid disconnection: In practice, two contactors connected in series with electrical and mechanical monitoring are usually used. This redundancy significantly increases operational safety.
Standard conformity – a mandatory requirement: Only standard-compliant devices are accepted by grid operators.