Residual Overvoltage Logic; Application Notes; Calculation For Solidly Earthed Systems; Figure 112: Residual Overvoltage Logic - GE P642 Technical Manual

P64x
4.2

RESIDUAL OVERVOLTAGE LOGIC

VN
VN>1 Voltage Set
VTS Fast Block
VN>1 Timer Blk

Figure 112: Residual Overvoltage logic

The Residual Overvoltage module (VN>) is a level detector that detects when the voltage magnitude exceeds a set
threshold, for each stage. When this happens, the comparator output produces a Start signal (VN>(n) Start), which
signifies the "Start of protection". This can be blocked by a VTS Fast block signal. This Start signal is applied to the
timer module. The output of the timer module is the VN> (n) Trip signal which is used to drive the tripping output
relay.
4.3

APPLICATION NOTES

4.3.1

CALCULATION FOR SOLIDLY EARTHED SYSTEMS

Consider a Phase-A to Earth fault on a simple radial system.
P64x-TM-EN-1.3
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Chapter 11 - Voltage Protection Functions
VN>1 Start
IDMT/DT VN>1 Trip
V00802
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