Basler Electric BE1-11t - Manual (Page 89)

9424200995 Rev H 77
Inverse Overcurrent (51) Protection
Nine inverse overcurrent (51) elements monitor the current applied to the BE1-11t. An element can be
configured to protect against overcurrent by monitoring a single- or three-phase system, neutral current,
positive-sequence current, negative-sequence current, ground current, or unbalanced current.
The nine, identical inverse overcurrent protection elements are designated 51-1, 51-2, 51-3, 51-4, 51-5,
51-6, 51-7, 51-8, and 51-9. Element logic connections are made on the BESTlogic
™Plus screen in
BESTCOMSPlus
® and element operational settings are configured on the Inverse Overcurrent settings
screen in BESTCOMSPlus. A summary of the logic inputs and outputs and operational settings appears
at the end of this chapter.
Note
BE1-11t protection systems enabled for IEC-61850 communication
(style Txxxx5xxxxxxxx) have their inverse overcurrent protection
elements fixed at nine inverse overcurrent elements without voltage
control.
BESTCOMSPlus Navigation Path: Settings Explorer, Protection, Current, Inverse Overcurrent (51)
HMI Navigation Path: Settings Explorer, Protection, Settings Group x (where x = 0 to 3), Current
Protection, Inverse Overcurrent 51
Element Operation
Inverse overcurrent protection can be used to protect equipment from damage caused by phase failure,
forward/reverse phase sequence, or phase unbalance.
Modes of Protection
Nine modes of protection are available: IA, IB, IC, Three-Phase, 3I0, I1, I2, IG, and Unbalance.
IA, IB, or IC Mode
The inverse overcurrent protection elements include three independent comparators and timers, one for
each phase. Mode selection determines which phase pickup is required to activate protection.
Three-Phase Mode
Three-phase mode provides overcurrent protection in a three-phase system when all three phases
increase above the Pickup setting.
3I0 Mode
3I0 mode provides neutral overcurrent protection in a three-phase system.
I1 Mode
I1 mode provides positive-sequence overcurrent protection in a three-phase system.
I2 Mode
I2 mode provides negative-sequence overcurrent protection in a three-phase system. Refer to the
Negative-Sequence Overcurrent (46) Protection chapter for more information.
IG Mode
IG mode provides ground fault protection in a three-phase system.
BE1-11t Inverse Overcurrent (51) Protection