GE Multilin 745

Introduction
Overview
745
Transformer Management Relay
http://www.GEindustrial.com/multilin
2–1
GE Multilin
2 Overview
Introduction
Description These instructions do not purport to cover all details or variations in equipment nor
provide for every possible contingency to be met in connection with installation,
operation, or maintenance. Should further information be desired or should
particular problems arise which are not covered sufficiently for the purchaser’s
purpose, the matter should be referred to the General Electric company.
To the extent required the products described herein meet applicable ANSI, IEEE,
and NEMA standards; but no such assurance is given with respect to local codes and
ordinances because they vary greatly.
The 745 Transformer Management Relay™ is a high speed, multi-processor based,
three-phase, two or three winding, transformer management relay intended for the
primary protection and management of small, medium and large power
transformers. The 745 combines Percent Differential, Overcurrent, Frequency, and
Overexcitation protection elements along with monitoring of individual harmonics,
and THD in one economical package.
The relay provides a variety of adaptive relaying features:
• Adaptive Harmonic Restraint which addresses the problem of false tripping
during inrush
• Adaptive Time Overcurrent elements which will adjust their pickup settings
based on the calculated transformer capability when supplying load currents
with high harmonic content
• Multiple Setpoint Groups which allow the user to enter and dynamically select
from up to four groups of relay settings to address the protection requirements
of different power system configurations
• Dynamic CT Ratio Mismatch Correction which monitors the on-load tap position
and automatically corrects for CT ratio mismatch
• FlexLogic™ which allows PLC style equations based on logic inputs and
protection elements to be assigned to any of the 745 outputs.
The 745 also includes a powerful testing and simulation feature. This allows the
protection engineer the ability to test the relay operation based on captured or
computer generated waveform data which can be converted to a digitized format
and downloaded into the 745’s simulation buffer for “playback”. A Waveform
Capture function that records waveform data for fault, inrush, or alarm conditions is
also provided.
The Auto-Configuration function eliminates the need for any special CT connections
by having all CTs connected in wye.