Solutions   for   Protecting   andManaging   the   Electrical   Network

ITI   7521

Alternator negative sequence protective relay

Alternators, being normally designed to supply balanced 3 phase currents, will only support a limited amount of unbalance in the phase currents. Out of balance in these currents, which causes abnormal heating of the rotor of the machine, may in fact have a highly damaging effect.
As the basic causes of unbalanced currents are numerous, it is essential to protect medium voltage alternators of a certain size against this condition.
The ITI relay may be put forward as a particularly interesting solution, because of its small size and low cost.

Their modular draw-out case, type R3, may be mounted either as a separate relay, flush or projection mounting, or as an alement in a standard 19" rack cradle.


  • Negative Sequence [46]


  • Nominal current: 1 or 5 A
  • Nominal frequency: 50 or 60 Hz
  • 1 definite time unit + 1 dependent time unit
  • Tripping time: from 12 to 120 sec.
  • n.2 output units (2NO or 1NO+1NC contacts for each unit)
  • n.1 hand reset mechanical opearation indicator


  Device Doc. Type Lang. Ref. Index
ITI 7521 Leaflet EN / FR -- --
ITI 7521 User Manual EN M.1727 B
ITI 7521 User Manual IT MI.1727 B
ITI 7521 Connection/Definition Diagram -- 9684 C