GE T35 User Manual

9-2 T35 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
SATURATION DETECTOR CHAPTER 9: THEORY OF OPERATION
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Figure 9-1: Directional principle operation during external faults
Figure 9-2: Directional principle operation during internal faults
The T35 implementation calculates the maximum angle for the considered currents and compares it against a fixed
threshold of 90°. The flag indicating whether the directional protection principle is satisfied is available as the FlexLogic
operand XFMR PCNT DIFF DIR A/B/C.
9.2 Saturation detector
9.2.1 CT saturation detection
The saturation detector of the T35 takes advantage of the fact that any CT operates correctly for a short period of time,
even under very large primary currents that would subsequently cause a very deep saturation. As a result, in the case of
an external fault, the differential current stays very low during the initial period of linear operation of the CTs while the

GE T35 Specifications

General

Brand	GE
Model	T35
Category	Relays
Language	English