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2 INTRODUCTION
2 INTRODUCTION 2.1OVERVIEW
The 750/760 Feeder Management Relays are microprocessor-based units intended for the management and primary pro-
tection of distribution feeders, as well as for the management and backup protection of buses, transformers, and transmis-
sion lines. The 760 relay is particularly suited to overhead feeders, where automatic reclosing is normally applied.
Each relay provides protection, control, and monitoring functions with both local and remote human interfaces. They also
display the present trip/alarm conditions, and most of the more than 35 measured system parameters. Recording of past
trip, alarm or control events, maximum demand levels, and energy consumption is also performed.
These relays contain many innovative features. To meet diverse utility standards and industry requirements, these features
have the flexibility to be programmed to meet specific user needs. This flexibility will naturally make a piece of equipment
difficult to learn. To aid new users in getting basic protection operating quickly, setpoints are set to typical default values and
advanced features are disabled. These settings can be reprogrammed at any time.
Programming can be accomplished with the front panel keys and display. Due to the numerous settings, this manual
method can be somewhat laborious. To simplify programming and provide a more intuitive interface, setpoints can be
entered with a PC running the 750/760PC software provided with the relay. Even with minimal computer knowledge, this
menu-driven software provides easy access to all front panel functions. Actual values and setpoints can be displayed,
altered, stored, and printed. If settings are stored in a setpoint file, they can be downloaded at any time to the front panel
program port of the relay via a computer cable connected to the serial port of any personal computer.
A summary of the available functions and a single-line diagram of protection and control features is shown below. For a
complete understanding of each features operation, refer to Chapter 5: Setpoints. The logic diagrams include a reference
to every setpoint related to a feature and show all logic signals passed between individual features. Information related to
the selection of settings for each setpoint is also provided.
SOURCE
N
dcmA
:
Bus VT
:
Trip
Breaker
52
Close
Line VT
1
3
GE Multilin
Courtesy of NationalSwitchgear.com
Feeder Management Relay
Level
Rate
27
59
1+2
1+2
25
Breaker Operation
Coil Monitors
27
3+4
55
50P
50P
Calc.
Calc.
50
Demand
Level
1+2
3Io
2 I
BF
50N
Level
GROUND
OPERATING CURRENT
SENSITIVE GROUND
OPERATING CURRENT
Figure 2–1: FUNCTIONAL BLOCK DIAGRAM
750/760 Feeder Management Relay
750/760
81U
81
Calc.
810
1+2
Decay
3Vo
Phase A only
59N
Calc.
V
VT
2
Fail
51V
Calc.
V 1
Current
Supervision
Zone
Coordination
Calc.
Calc.
50P
51P
79X
1 I
I 2
1+2
1+2
760 Only
Control
46/50
46/51
46/67
Control
50N
51N
67N
1+2
1+2
Control
51G
67G
50G
Control
50SG
67SG
51SG
Control
2.1 OVERVIEW
2.1.1 DESCRIPTION
OUTPUTS
¨
Trip Relay
Close Relay
5 Auxiliary Relays
Self-Test Warning Relay
8 Analog Outputs
CONTROL
Synchronism Check
Cold Load Pickup
Manual Close
Undervoltage Restoration
Underfrequency Restoration
Transfer
Auto Reclose (760)
MONITOR
67P
Power Factor
Demand
Tripping
47
Arcing
Fault Locator
Analog Input
Calc.
V2
Overfrequency
VT Failure
Event Recorder
Oscillograph
Data Logger
Calc.
COMMUNICATIONS
-Vo
1 x RS232
2 x RS485 OR
1 x RS422
Modbus RTU
DNP 3.0
818840AD.dwg
* POLARIZING CURRENT AND GND CURRENT
ARE MUTUALLY EXCLUSIVE SINCE BOTH USE
THE SAME RELAY CT INPUT TERMINALS
2
2-1
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