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2 PRODUCT DESCRIPTION
2 PRODUCT DESCRIPTION 2.1INTRODUCTION
The B90 Low Impedance Bus Differential System is a microprocessor-based architecture that provides protection and
metering for busbars with up to 24 feeders. The B90 protection system is a centralized architecture built on three, four, or
more B90 IEDs as per requirements of a particular application. Each IED of the B90 system is a full-featured B90 and as
such can be accessed and programmed individually. Protection and supervisory functions of the B90 include:
•
Multi-zone differential protection with both restrained (percent, biased) and unrestrained (unbiased, instantaneous)
functions incorporated. Differential protection is fast (typical response time: ¾ of a power cycle; maximum response
time: 1 power cycle) and secure. Security is achieved by using fast and reliable CT saturation detection algorithm and
a second, phase comparison operating principle.
•
Check-zone functionality is provided by programming one of the differential zones to enclose the entire bus.
•
Dynamic bus replica functionality and multi-zone protection allowing application of the B90 to multi-section re-configu-
rable busbars.
•
Isolator monitoring feature monitors up to 48 isolators from a single B90 IED.
•
End fault protection (dead zone protection) is provided for up to 24 breakers.
•
CT trouble monitoring function is provided for each zone of differential protection.
•
Breaker fail function is provided for up to 24 breakers.
•
An instantaneous overcurrent function is available per each current input of the B90 system.
•
A time overcurrent function is available per each current input of the B90 system for backup protection.
•
An undervoltage function is provided per each voltage input of the B90 system for supervision purposes.
Voltage and current metering is built into the relay as a standard feature. Current parameters are available as total wave-
form RMS magnitude, or as fundamental frequency only RMS magnitude and angle (phasor).
Diagnostic features include a sequence of records capable of storing 1024 time-tagged events per each B90 IED and oscil-
lography that is user-programmable as to sampling rate (up to 64 samples per cycle), content, writing mode, and record
length. The internal clock used for time-tagging can be synchronized with an IRIG-B signal or via the SNTP protocol over
the Ethernet port. This precise time stamping allows the sequence of events to be determined between the B90 IEDs and
throughout the system. Events can also be programmed (via FlexLogic™ equations) to trigger oscillography data capture
which may be set to record the measured parameters before and after the event for viewing on a personal computer (PC).
These tools significantly reduce troubleshooting time and simplify report generation in the event of a system fault.
A faceplate RS232 port may be used to connect to a PC for the programming of settings and the monitoring of actual val-
ues. A variety of communications modules are available. Two rear RS485 ports allow independent access by operating and
engineering staff. All serial ports use the Modbus RTU protocol. The RS485 ports may be connected to system computers
with baud rates up to 115.2 kbps. The RS232 port has a fixed baud rate of 19.2 kbps. The 100Base-FX Ethernet interface
provides fast, reliable communications in noisy environments. The Ethernet port supports IEC 61850, Modbus/TCP, and
TFTP protocols, PTP (according to IEEE Std. 1588-2008 or IEC 61588), and allows access to the relay via any standard
web browser (B90 web pages). The IEC 60870-5-104 protocol is supported on the Ethernet port, and DNP 3.0 and IEC
60870-5-104 cannot be enabled at the same time.
The B90 IEDs use flash memory technology which allows field upgrading as new features are added. The following Single
line diagram illustrates the relay functionality using ANSI (American National Standards Institute) device numbers.
The available zones of differential protection and their size (maximum number of inputs) are optional and
controlled by the software option portion of the order code. The breaker failure function is also optional.
See the ordering section for detailed information on the maximum number of zones and inputs for a given
model. In addition, different applications may require differing numbers of B90 IEDs with different hard-
ware configurations.
Table 2–1: ANSI DEVICE NUMBERS AND FUNCTIONS
DEVICE
FUNCTION
27
Undervoltage
50
Instantaneous overcurrent
50/74
CT trouble
GE Multilin
DEVICE
FUNCTION
50/87
Unrestrained bus differential
51
Time overcurrent
50BP
Breaker failure
B90 Low Impedance Bus Differential System
2.1 INTRODUCTION
2.1.1 OVERVIEW
2
2-1
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