{}

Our Brands

Impact-Company-Logo-English Black-01-177x54

Welcome to the Schneider Electric Website

Welcome to our website.
How can we help you today?
What is the difference between "Sum 3I" and "Input Io" when setting the ANSI 50/51N protection in a Sepam relay?
When setting the ANSI 50/51N protection, the Sepam relay provides 2 different options for residual current type: "Sum 3I" and "Input Io".
ANSI 50/51N protection
The residual current type depends on the wiring of the current sensors to the relay. If, for example the relay is wired with a standard 3-phase current connection without wiring the Ir input of the CCA634 or using a CSH zero-sequence CT, the "Sum 31" option needs to be selected. The measurement of the 3-phase currents allows the "calculation" of residual current.
3 CT connection

Note: A 2-phase current connection will not calculate residual current.

If, for example, the CCA634 Ir input is wired or a CSH zero-sequence ct is used, the Sepam will "measure" the residual current and "Input Io" needs to be selected when configuring 50/51N.

Ir input is wired or a CSH zero-sequence CT

Schneider Electric India

Explore more
Range:
Articles that might be helpful Users group

Discuss this topic with experts

Visit our Community for first-hand insights from experts and peers on this topic and more.
Explore more
Range: