Basler Electric BE1-851 - Manual (Page 18)

Each current sensing circuit is low burden and isolated. Negative-sequence current magnitudes are
derived from the three-phase currents. Neutral current input is available for direct measurement of the
current in a transformer neutral, tertiary winding, or flux balancing current transformer.
Contact Sensing Inputs
Four programmable contact sensing inputs (IN1, IN2, IN3, and IN4) with programmable signal
conditioning provide a binary logic interface to the protection and control system. Each input’s function
and labeling is programmable using BESTlogic. A user-meaningful name can be assigned to each input
and to each state (energized and de-energized) for use in reporting functions.
Contact Outputs
Five programmable general-purpose contact outputs (OUT1, OUT2, OUT3, OUT4, and OUT5) provide a
binary logic interface to the protection and control system. One programmable, fail-safe contact output
(OUTA) provides an alarm output. Each output’s function and labeling is programmable using BESTlogic.
A user-meaningful name can be assigned to each output and to each state (open and closed) for use in
reporting functions. Output logic can be overridden to open, close, or pulse each output contact for testing
or control purposes. All output contacts are trip rated.
Protection and Control Functions
Protection functions consist of overcurrent, breaker reclosing, and breaker failure protection and general-
purpose logic timers. Setting groups and virtual control switches make up the control functions. The
following paragraphs describe each protection and control function.
Overcurrent Protection
Overcurrent protection is provided by six instantaneous overcurrent functions and three time-overcurrent
functions.
Each instantaneous overcurrent function has a settable time delay. Sensing input type G relays have two
phase and four neutral elements. Sensing input type H relays have two phase, two neutral, and two
negative-sequence elements. Phase elements include 50TP and 150TP. Neutral elements include 50TN,
150TN, 250TN, and 350TN. Negative-sequence elements include 50TQ and 150TQ.
A 51P phase element, 51Q negative-sequence element, and 51N and 151N neutral elements are
provided for time overcurrent functions. Sensing input type G relays have one phase and two neutral
elements. Sensing input type H units have one phase, one neutral, and one negative-sequence element.
Time overcurrent functions employ a dynamic integrating timing algorithm covering a range from pickup to
40 times pickup with selectable instantaneous or integrated reset characteristics. Time overcurrent curves
conform to the IEEE C37.112 document and include seven curves similar to Westinghouse/ABB CO
curves, five curves similar to GE IAC curves, IEC types A, B, C, and G, a fixed time curve, and a user
programmable curve.
Breaker Failure Protection
One breaker failure protection block (BF) provides programmable breaker failure protection.
General Purpose Logic Timers
Two general-purpose logic timers (62, 162) with six modes of operation are provided. Four general-
purpose logic timers (62, 162, 262, 362) are provided when style option 1 is V or W.
Setting Groups
Four setting groups allow adaptive relaying to be implemented to optimize BE1-851 settings for various
operating conditions. Automatic and external logic can be employed to select the active setting group.
Virtual Control Switches
BE1-851 virtual control switches include one virtual breaker control switch and four virtual switches.
Trip and close control of a selected breaker can be controlled by the virtual breaker control switch (101).
The virtual breaker control switch is accessed locally from the human-machine interface (HMI) or remotely
from the communication ports.
Additional control is provided by the four virtual switches: 43, 143, 243∗, and 343∗. These virtual switches
are accessed locally from the HMI or remotely from the communication ports. Virtual switches can be
used to trip and close additional switches or breakers, or enable and disable certain functions.
∗
243 and 343 are not available when style option 1 is V or W.
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