1-2 BE1-951 General Information 9328900990 Rev L
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 function and
label is programmable using BESTlogic. A user-meaningful label 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 function and label 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, Voltage, Frequency, Breaker Reclosing, Fuse Loss, 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.
Directional Overcurrent Protection
Directional overcurrent protection is provided by six instantaneous overcurrent functions and four time
overcurrent functions. Digital signal processing filters out unwanted harmonic components while providing
fast overcurrent response with limited transient overreach and overtravel.
Each instantaneous overcurrent function has a settable time delay. Phase elements include 50TP,
150TP. Neutral elements include 50TN, and 150TN. Negative elements include 50TQ and 150TQ.
Inverse time-overcurrent functions are provided for phase, neutral, and negative protection. A 51P phase
element, 51N and 151N neutral elements, and a 51Q negative element are provided. 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 PC37.112 document and include seven curves similar to Westinghouse/ABB CO curves, five curves
similar to GE IAC curves, a fixed time curve, and a user programmable curve. Phase time overcurrent
functions can be voltage restrained or controlled for generator backup applications.
Each overcurrent element can be individually set for forward, reverse, or non-directional control.
Voltage Protection
One volts per hertz protective element provides overexcitation protection for a generator and/or
transformer (24).
One phase overvoltage and one phase undervoltage element provides over/undervoltage protection
(27P, 59P). Phase overvoltage protection can be set for one of three, two of three, or three of three logic.
When a four-wire voltage transformer connection is used, overvoltage protection can be set for either
phase-to-phase voltage or phase-to-neutral voltage.
Two auxiliary overvoltage and one auxiliary undervoltage element provides over/undervoltage protection
(27X, 59X, 159X). Auxiliary voltage protection elements can be set to individually monitor the auxiliary
voltage fundamental, third harmonic or phase 3V
0
voltages. Ground unbalance protection is provided
when the optional auxiliary voltage input is connected to a source of 3V
0
such as a broken delta VT.
With the optional auxiliary voltage input connected to the bus, one sync-check function provides
synchronism protection (25). Sync-check protection checks for phase angle difference, magnitude
difference, frequency difference (slip) and, optionally, if the three-phase VT frequency is greater than the
auxiliary VT frequency. Two voltage monitor outputs (25VM1 and 25VM2) provide independent dead/live
voltage closing logic.
One negative-sequence overvoltage element provides protection for phase unbalance or a reverse
system phase (47).
Voltage transformer circuit monitoring adds security by detecting problems in the voltage transformer
sensing circuits and preventing misoperations of the 27P, 47, 59P, and the 51/27 function (60FL).
Directional Power Protection
One directional power element (32) is included in the BE1-951 and can be set for forward or reverse
power protection. The relay can be used for any application requiring directional power flow detection
To Next Page
Loading...
Need help?
General