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DESCRIPTION OF THE 345 TRANSFORMER PROTECTION SYSTEM
4
ANSI Device
51P
51G
51N
51_2
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
Phase Timed Overcurrent
Ground/Sensitive Ground Timed Overcurrent
Neutral Timed Overcurrent
Negative Sequence Timed Overcurrent
345 TRANSFORMER PROTECTION SYSTEM – QUICKSTART GUIDE
CHAPTER 1: INTRODUCTION
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