1–4 845 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
DESCRIPTION OF THE 845 TRANSFORMER PROTECTION RELAY CHAPTER 1: INTRODUCTION
Table 1-1: ANSI Device Numbers and Functions
Table 1-2: Other Device Functions
ANSI Device Description
24 Volts per Hertz
25 Synchrocheck
27P Phase Undervoltage
27X Auxiliary Undervoltage
32 Directional Power
49 Hottest Spot Temperature
Aging Factor
Loss of Life
50/87 Instantaneous Differential Overcurrent
50BF Breaker Failure
50G Ground Instantaneous Overcurrent
50N Neutral Instantaneous Overcurrent
50P Phase Instantaneous Overcurrent
50_2 Negative Sequence Instantaneous Overcurrent
51G Ground Time Overcurrent
51N Neutral Time Overcurrent
51P Phase Time Overcurrent
51_2 Negative Sequence Time Overcurrent
55 Power Factor
59N Neutral Overvoltage
59P Phase Overvoltage
59X Auxiliary Overvoltage
59_2 Negative Sequence Overvoltage
67G Ground Directional Element
67N Neutral Directional Element
67P Phase Directional Element
81O Overfrequency
81U Underfrequency
81R Frequency Rate of Change
87G Restricted Ground Fault (RGF)
87T Transformer Differential
AFP Arc Flash Protection
VTFF Voltage Transformer Fuse Failure
Description
Analog Input
Analog Output
Breaker Arcing Current (I
2
t)
Breaker Control
Breaker Health
Data Logger
Demand
Digital Counters
Event Recorder
Fault Report
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