Terminal blocks

For short-circuiting current transformers and for the purpose of for recurring comparative measurements, special terminal strips for the DIN rail are recommended. These consist of a cross-disconnect terminal with measuring and Measuring and testing device, insulated bridges for earthing and short-circuiting the Transformer terminal.

Under no circumstances should the current transformer secondary circuit be be opened when current is flowing in the primary circuit.

The output of the current transformer is a current source. With increasing load, the output voltage therefore increases (according to the relationship Relationship U = R x I) until saturation is reached. Above Saturation, the peak voltage continues to rise with increasing distortion and reaches its maximum value with an infinitely large load, i.e. open secondary Secondary terminals. High voltage peaks can therefore occur with open transformers which are a danger to people and can destroy the transformer and measuring device can be destroyed when reconnected.

This means that open operation should be avoided and unbonded transformers must be short-circuited.