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2.2 INTRODUCTION
2.2INTRODUCTION
•
MIFII is a microprocessor-based protection relay. designed for the following applications:Main Protection for Medium
and Low voltage feeders.
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Main Protection for Medium size Motors.
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Main Protection for Medium and Low power Transformers (less than 10MVA).
•
Differential Protection for Motors, if a CT differential connection is available.
2
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Backup Protection for power Transformers (for any power level).
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Backup Protection for Generators.
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Backup Protection for Transmission lines.
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Backup Protection for substation busbars.
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Thermal Image Protection/Supervision for Cables, Power Transformers, Grounding Resistors and Generation
Elements.
Negligible over-travel and a high dropout to pick-up ratio (97% typical), along with the possibility of adjusting a time delay
for the instantaneous elements, allow optimal coordination without compromising selectivity.
Both front RS232 port and rear RS485 port may be used to connect a PC for programming settings, monitoring actual
values and for retrieving stored information (list of events, oscillography, etc.). All serial ports of the standard model use the
Modbus® RTU protocol and may be connected to system computers with baud rates from 300, 600, 1200, 4800, 9600 and
19200 bps. The rear RS485 port can be converted into an RS232 port or into a fiber optic (plastic or glass) serial port by
using GE Multilin DAC300, F485 or RS232/485 module, or any other standard converter. The EnerVista MII SETUP
communication software is the Windows® based program used to communicate with the relay. A password system has
been implemented to restrict setting changes to non-authorized users, both by relay keypad and PC software.
A special model with IEC60870-5-103 protocol is also available, which uses the rear port with 9600 and 19200 bps baud
rates.
MIFII uses flash memory technology, which allows field upgrades (through EnerVista MII SETUP software) as new features
are added. Upgrades can only be performed through the communications port on the front of the unit.
The following one line (single line) diagram (Figure 2–1:) illustrates the relay functionality using ANSI (American National
Standards Institute) device numbers.
2-2
Figure 2–1: ONE LINE (SINGLE LINE) DIAGRAM SHOWING MIFII FUNCTIONS
MIFII Digital Feeder Relay
2 PRODUCT DESCRIPTION
GEK-106237P
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