Delivery quality is an umbrella term that encompasses both delivery reliability and voltage quality. Delivery reliability indicates how often one has access to electrical energy, while voltage quality reflects the usability of that electrical energy.
For electrical energy to be usable, the voltage must meet certain standards of quality; otherwise, it can potentially lead to electrical appliances experiencing a shorter lifespan or being damaged.
The Norwegian Water Resources and Energy Directorate (NVE) has established regulations on delivery quality in the power system. These regulations provide more detailed provisions on the quality of the voltage that network operators must deliver to their customers.