Summation current transformers
Summation current transformers SSR-2 to SSR-9 are used to summarize secondary currents of several main c.t.`s in order to measure with one instrument only. The output current again constitutes a standardized quantity. That means the primary currents are not only added but also divided by the number of inputs.
If using unequal main c.t.`s the ratio of the lowest primary current to the highest one should not exceed 1:10. When ordering in case of unequal main c.t.`s the ratio of each of them has to be specified absolutely. Unused primary connections have to be open circuited as opposed to the short circuiting of secondary connections.