RED521 1MRK002003-BA 数值差分保护端子RED 521

REL561

The numerical Differential Protection Terminal RED 521 provides fast and selective phase-segregated protection for busbars, as well as generators, autotransformers, shut reactors and capacitor banks. The superior security and dependability of this terminal is based on ABB’s deep knowledge of busbar protection.
As an option, RED 521 offers a more cost-efficient solution using the summation CT principle.
The RED 521 terminal is more than just a first-class product. It is supplied with a value-adding information package about the product and its use in your application. Information such as technical data, user documentation and connection diagrams is essential to ensure the smooth and efficient use of the terminal throughout its lifetime. You can access this information easily via the operator ’s workplace or from your PC with InformIT Aspect Object Viewer freeware.
Fast and stable at the same time
The extremely short operate time of RED 521 is typically 10-15 ms at all internal faults, regardless of the number of connected feeders. At the same time, the terminal maintains complete stability for external faults, even when heavy CT saturation occurs. This unique combination of speed and stability is essential for effective busbar protection. RED 521 has very low CT requirements compared to other numerical differential protection devices due to its unique measuring principle. This also allows sharing of CT circuits with other relays to save costs. The low CT requirements guarantee stability and correct operation as long as the CT is not saturated for at least two milliseconds during each power system cycle.