Basler Electric BE1-11t - Manual (Page 81)

9424200995 Rev H 69
Instantaneous Overcurrent (50)
Protection
Nine instantaneous overcurrent (50) 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 instantaneous overcurrent protection elements are designated 50-1, 50-2, 50-3, 50-4,
50-5, 50-6, 50-7, 50-8, and 50-9. Element logic connections are made on the BESTlogic
™Plus screen in
BESTCOMSPlus
® and element operational settings are configured on the Instantaneous Overcurrent
settings screen in BESTCOMSPlus. A summary of the logic inputs and outputs and operational settings
appears at the end of this chapter.
BESTCOMSPlus Navigation Path: Settings Explorer, Protection, Current, Instantaneous Overcurrent
(50)
HMI Navigation Path: Settings Explorer, Protection, Settings Group x (where x = 0 to 3), Current
Protection, Instant Overcurrent 50
Element Operation
Instantaneous 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 instantaneous overcurrent protection elements include three independent comparators, one for each
phase. Mode selection determines which phase pickup is required to activate protection.
Three-Phase Mode
The instantaneous overcurrent protection elements include three independent comparators, one for each
phase. Protection is activated when any of the three phases increases 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.
Unbalance Mode
Unbalance mode provides unbalanced current protection. Two methods are available to calculate
unbalanced current. The first method is based on the negative-sequence current divided by the positive-
sequence current while the second method is based on the average current. The calculation method must
BE1-11t Instantaneous Overcurrent (50) Protection