The current transformers for tariffs with a primary current range from 25 A up to 3000 A with accuracy classes of 0.2s, 0.2, 0.5s, 0.5 have the national certificates of Germany as well as of other European countries.
The transformers have been approved by the Physikalisch Technische Bundesanstalt (PTB) Braunschweig (an authorized German testing laboratory) and can be recognized by a stylized S on the label.

An ‘E’ is placed before the usual type mark.

The calibration of the transformers is documented by an official lead seal as well as an additional affixed yellow calibration stamp. The fees for the calibration are calculated with the applicable official regulation.

The calibration of the transformers is performed upon request at the ‘Staatlich anerkannte Prüfstelle für Messgeräte für Elektrizität EA90’ (State Approved Testing Laboratories for Measuring Appliances for Electricity EA90).