ABB 615 Series - Operation Principle

4.2.8.4 Operation principle
The function can be enabled and disabled with the Operation setting. The corresponding
parameter values are “Enable” and “Disable”.
The operation of 67YN can be described using a module diagram. All the modules in the
diagram are explained in the following sections.
IG
VG
Transient
detector
General
fault
criterion
Operation
logic
Timer
BLOCK
RELEASE
RESET
Multi-
frequency
admittance
calculation
TRIP
PICKUP
BLK_EF
INTR_EF
PEAK_IND
Fault
direction
determination
GUID-42CB0D5D-7A13-4496-8218-5F65CB8EA6B5 V1 EN
Figure 211: Functional module diagram
General fault criterion
The General fault criterion (GFC) module monitors the presence of ground fault in the
network and it is based on the value of the fundamental frequency zero-sequence voltage
defined as the vector sum of fundamental frequency phase voltage phasors divided by
three.
V V V V
A B C0
1 1 1 1
3= + +
(
)
/
GUID-BF09651A-0D05-4805-9560-011B279495EC V1 EN (Equation 54)
When the magnitude of
V
o
1
exceeds setting Voltage pickup value, a ground fault is
detected. The GFC module reports the exceeded value to the Fault direction determination
module and Operation logic. The reporting is referenced as General Fault Criterion
release.
The setting Voltage pickup value defines the basic sensitivity of the 67YN function. To
avoid unselective pickup or trip, Voltage pickup value must always be set to a value which
exceeds the maximum healthy-state zero-sequence voltage value, taking into
1MAC059074-MB A Section 4
Protection functions
615 series ANSI 439
Technical Manual