BASLER Electric BE1-951 Overcurrent Protection System
BASLER Electric BE1-951 Overcurrent Protection System
The BE1-951 Overcurrent Protection System is an economical, microprocessor based, multifunction
system that is available in a drawout, H1 (half-rack), S1. and S1 double-ended package. BE1-951
features include:
• Directional Three-Phase Overcurrent Protection
• Directional Ground Overcurrent Protection
• Directional Negative-Sequence Overcurrent Protection
• Directional Power Protection
• Control Protection
• Breaker Failure Protection
• Automatic Reclosing
• Voltage Protection
• Frequency Protection
• Breaker Monitoring
• Metering Functions
• Communication
BE1-951 relays have four programmable contact sensing inputs, five programmable outputs, and one
alarm output. Outputs can be assigned to perform protection, control, or indicator operations through
logical programming. For example, protection functions could be programmed to cause a protective trip.
Control functions could be programmed to cause a manual trip, manual close, or automatic reclose.
Indicators could be configured to annunciate relay failure, a settings group change, and others.
Protection scheme designers may select from a number of pre-programmed logic schemes that perform
the most common protection and control requirements. Alternately, a custom scheme can be created
using BESTlogic™.
A simplified Getting Started procedure for BE1-951 users is provided in Section 2. Quick Start.
Features
The BE1-951 relay includes many features for the protection, monitoring, and control of power system
equipment. These features include protection and control functions, metering functions, and reporting and
alarm functions. A highly flexible programmable logic system called BESTlogic allows the user to apply
the available functions with complete flexibility and customize the system to meet the requirements of the
protected power system. Programmable I/O, extensive communication features, and an advanced HMI
(human-machine interface) provide easy access to the features provided.
The following information summarizes the capabilities of this multifunction device. Each feature, along
with how to set it up and how to use its outputs is described in complete detail in the later sections of this
manual.
Input and Output Functions
Input functions consist of Power System Measurement and Contact Sensing Inputs. Programmable
Contact Outputs make up the output functions. Input and Output functions are described in the following
paragraphs.
Power System Measurement Functions
Three-phase currents and voltages are digitally sampled and the fundamental is extracted using a
Discrete Fourier Transform (DFT) algorithm.
The voltage sensing circuits automatically configure themselves internally for single-phase, three wire or
four wire voltage transformer circuits. Voltage sensing circuitry provides voltage protection, frequency
protection, and watt/var metering. Neutral (residual) and negative voltage magnitudes are derived from
the three-phase voltages. Digital sampling of the measured frequency provides high accuracy at off
nominal values.
BE1-951
An auxiliary voltage sensing input provides protection capabilities for over/undervoltage monitoring of the
first and third harmonic of the VT source connected to the Vx input. This capability is useful for ground
fault protection and sync-check functions.
Each current sensing circuit is low burden and isolated. Neutral (residual) and negative current
magnitudes are derived from the three-phase currents. An optional independent ground 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 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 3V0 voltages. Ground unbalance protection is provided
when the optional auxiliary voltage input is connected to a source of 3V0 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 misoperation of the 27P, 47. 59P, and the 51/27 functions (60FL).