Three-Phase Underexcitation Protection Uexpdis - ABB RELION REX640 Technical Manual

Section 4
Protection functions
4.7.3
4.7.3.1
4.7.3.2
4.7.3.3
4.7.3.4
932

Three-phase underexcitation protection UEXPDIS

Identification
Function description
Three-phase underexcitation protection
Function block
GUID-65009094-9763-4444-B446-E5267DF06278 V1 EN
Figure 504: Function block
Functionality
The three-phase underexcitation protection function UEXPDIS is used to protect the
synchronous machine against the underexcitation or loss of excitation condition.
The protection is based on the offset-mho circular characteristics on the impedance
plane. The function calculates the apparent impedance from the machine terminal
voltages and currents. If the impedance vector enters the offset-mho circle, the
function gives the operating signal after a set definite time. The operating time
characteristics are according to definite time (DT).
This function contains a blocking functionality. It is possible to block the function
outputs, timer or the function itself.
Analog channel configuration
UEXPDIS has two analog group inputs which all must be properly configured.
Table 866: Analog inputs
Input
I3P
U3P
See the preprocessing function blocks in this document for the
possible signal sources.
There are a few special conditions which must be noted with the configuration.
IEC 61850 IEC 60617
identification identification
UEXPDIS X<
Description
Three-phase currents
Three-phase voltages
1MRS759142 C
ANSI/IEEE C37.2
device number
40
REX640
Technical Manual