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 
- 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