GE MiCOM P142 Agile User Manual

9.2 NON-DIRECTIONAL NEGATIVE SEQUENCE OVERCURRENT LOGIC
I2>1 Tmr Blk
V00607
I2>1 Start
I2>1 Trip
CTS Block
I2> Blocking
2H Blocks I2>1
I2>1 Current Set
& IDMT/DT
Timer Settings
&
&
I2> Inhibit
I2H Any Start
Note: This diagram does not show all stages . Other stages follow
similar principles.
I2
Figure 45: Negative Sequence Overcurrent logic - non-directional operation
For Negativ
e Phase Sequence O
vercurrent Protection, the energising quanitity I2> is compared with the threshold
voltage I2>1 Current Set. If the value exceeds this setting a Start signal (I2>1 Start) is generated, provided there
are no blocks.
The function can be blocked if a CTS or second harmonic condition is detected.
The I2>1 Start signal is fed into a timer to produce the I2>1 trip signal. The timer can be blocked by the timer block
signal I2>1 Tmr Blk.
This diagram and description applies to each stage.
9.3 COMPOSITE EARTH FAULT START LOGIC
1
IN1>1 Start
V02004
IN1>2 Start
IN1>3 Start
IN1>4 Start
IN2>1 Start
IN2>2 Start
IN2>3 Start
IN2>4 Start
ISEF>1 Start
ISEF>2 Start
ISEF>3 Start
ISEF>4 Start
Start N
VN>1 Start
VN>2 Start
VN>3 Start
Figure 46: Composite Earth Fault Start Logic
9.4 DIRECTIONAL ELEMENT
Where negative phase sequence current may flow in either direction, directional control should be used.
Directionality is achiev
ed by comparing the angle between the negative phase sequence voltage and the negative
phase sequence current. A directional element is available for all of the negative sequence overcurrent stages.
This is found in the I2> Direction cell for the relevant stage. It can be set to non-directional, directional forward, or
directional reverse.
A suitable characteristic angle setting (I2> Char Angle) is chosen to provide optimum performance. This setting
should be set equal to the phase angle of the negative sequence current with respect to the inverted negative
sequence voltage (–V2), in order to be at the centre of the directional characteristic.
P14x Chapter 6 - Current Protection Functions
P14xEd1-TM-EN-1 117

GE MiCOM P142 Agile Specifications

General

Brand	GE
Model	MiCOM P142 Agile
Category	Control Unit
Language	English