Basler Electric BE1-11m - Manual (Page 65)

9424200996 Rev L 53
Instantaneous Undercurrent (37)
Protection
The instantaneous undercurrent (37) element monitors the three-phase sensing current and protects
against loss of load conditions, such as a breaking motor belt. This protective function will trip the motor
when a loss of load occurs.
Element logic connections are made on the BESTlogic
™Plus screen in BESTCOMSPlus® and element
operational settings are configured on the Instantaneous Undercurrent 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 Undercurrent
(37)
HMI Navigation Path: Settings Explorer, Protection, Settings Group x (where x = 0 to 3), Current
Protection, Instant Undercurrent 37
Element Operation
When enabled, the instantaneous undercurrent element monitors IA, IB, and IC and makes pickup and
trip decisions from the lowest of the three phases.
CT Source
The CT Source setting configures the instantaneous undercurrent element to monitor CT circuit 1 or CT
circuit 2 on protection systems equipped with two sets of CTs. CT circuit 1 terminals are designated D1
(IA1) through D8 (IG1) and CT circuit 2 terminals are designated F1 (IA2) through F8 (IG2). For an
illustration, refer to the
Terminals and Connectors chapter.
Pickup and Trip
The Pickup output occurs first, followed by the Trip output.
Pickup
The Pickup output becomes true when the measured current decreases below the current threshold
established by the Pickup setting. In BESTlogicPlus, the Pickup output can be connected to other logic
elements to annunciate the condition, control other elements in logic, and start the fault recorder (logic
element FAULTTRIG).
Assertion of the Pickup output initiates a timer that begins timing to a trip. The duration of the timer is
established by the Time Delay setting. A Time Delay of zero (0) makes the 37 element instantaneous with
no intentional time delay.
If the pickup condition subsides before the element delay expires, the timer and Pickup output are reset,
no corrective action is taken, and the element is rearmed for any other occurrences of undercurrent.
Trip
The Trip output becomes true if an undercurrent condition persists for the duration of the element Time
Delay. In BESTlogicPlus, the Trip output can be connected to other logic elements and to a physical relay
output to annunciate the condition and to initiate corrective action. If a target is enabled for the element,
the BE1-11m will record a target when the Trip output becomes true. See the
Fault Reporting chapter for
more information about target reporting.
BE1-11m Instantaneous Undercurrent (37) Protection