GE SR345 Instruction Manual page 11

CHAPTER 1: INTRODUCTION
345 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
Courtesy of NationalSwitchgear.com
Table 1: Protection Elements
ANSI Device Description
87T Percent Differential
50/87 Instantaneous Differential
87G Restricted Ground Fault
49 Thermal Model
50P Phase Instantaneous Overcurrent
50G Ground/Sensitive Ground Instantaneous Overcurrent
50N Neutral Instantaneous Overcurrent
50BF Breaker Failure
51P Phase Timed Overcurrent
51G Ground/Sensitive Ground Timed Overcurrent
51N Neutral Timed Overcurrent
51_2 Negative Sequence Timed Overcurrent
The 345 relay has two identical setpoint groups, with the same set of protection elements.
By default setpoint group 1 will be active. Setpoint group 2 can be activated by
programming the conditions under S4 Control/Change Setpoint Group menu.
Depending on the relay order code, the type and number of protection elements per
setpoint group changes. The full set of protection elements will be available in the setpoint
group, if the "Advanced configuration (letter M) is selected in the order code. This includes
one Transformer Percent Differential element, one Instantaneous Differential element, two
Restricted Ground Fault elements, one Thermal Model, two Breaker Failure elements, two
of each Phase-, Ground-, and Neutral Instantaneous Overcurrent elements, two of each
Phase-, Ground-, Neutral Timed Overcurrent elements, and two Negative Sequence Timed
Overcurrent elements. Some of the protection elements are common for the transformer
protection: Percent and Instantaneous differential elements, Thermal Model, and others
are generic with programmable AC inputs from either winding currents: the Restricted
Ground Fault 1(2), the Phase-, Ground-, and Neutral IOC1(2), the Phase-, Ground-, and
Neutral TOC1(2), and the Negative Sequence TOC1(2) elements.
DESCRIPTION OF THE 345 TRANSFORMER PROTECTION SYSTEM
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