Summation current transformers

REDUR summation current transformers can do more than just add or distract 1 plus 1

Summation current transformers are used to add up secondary currents of multiple main current transformers in order to measure with one instrument only.

The output signal is again a standardised signal which is received by adding the input currents and divide the sum by the quantity of inputs. But is has to be differentiated between summation current transformers for equal or unequal main current transformers.
The ratios of the main unequal CTs have always been advised together with the order as the primary input current are always been accordingly weighted. The ratio of the primary currents should not be more than 10 : 1 (biggest to smallest primary current).
Unused primary terminals have to remain open and shall never be short-circuited in contrary to the secondary terminals.

The currents are always vectorially added under consideration of the amount and phase disposal of the current. The sum of the currents can add up to Zero e.g. in case of a differential current measurement. The standard application is the addition of currents of the same phase. With a reverse connection of the main current transformers it is as well possible to subtract currents.

For equal main current transformers it is independent where the input currents are connected. But in case of unequal main CTs each has its definded input slot.

Robust, powerful and configurable

REDUR differential current transformers feature numerous positive properties. Four of them are:

  • For up to 9 inputs currents
  • For equal or unequal main CTs
  • Break-prrof enclosure of ABS plastic, difficult to inflame (acc. to UL 94)
  • Protection class IP40 (enclosure)

Learn more about our other products.  Discover our innovative current transformers with integrated transducer or view all low-voltage current transformers from the REGULUS and IPNG series at a glance. Feel free to contact us if you have any questions. We will be glad to assist you. 


If you are interested in a differential current transformers, we would like to offer you a detailed consultation. Contact REDUR directly and we will get back to you as soon as possible. 

Interested in a Summation current transformers? Contact us!

* Required field