Identification; Functionality; Stator Earth Fault Protection, Injection Based Sttiphiz - ABB REG670 Technical Manual

1MRK502052-UEN B
7.9
7.9.1
7.9.2
Technical manual
Function
Alarm limit of fault resistance
Operate time, start at R ~ 0 Ω
f
and filter length = 1 s
Operate time, trip at R ~ 0 Ω and
f
filter length = 1 s
Alarm time delay at R ~ 0 Ω and
f
filter length = 1 s
100% stator earth fault protection, injection based
STTIPHIZ

Identification

Function description
100% stator earth fault protection,
injection based

Functionality

The 100% stator earth-fault protection STTIPHIZ is used to detect earth faults in the
stator windings of generators and motors. STTIPHIZ is applicable for generators
connected to the power system through a unit transformer in a block connection. An
independent signal with a certain frequency different from the generator rated
frequency is injected into the stator circuit. The responce of this injected signal is used
to detect stator earth faults.
To implement the above concept, a separate injection box is required. The injection
box generates a square wave voltage signal which for example can be fed into the
secondary winding of the generator neutral point voltage transformer or grounding
transformer. This signal propagates through this transformer into the stator circuit.
The magnitude of the injected voltage signal is measured on the secondary side of the
neutral point voltage transformer or grounding transformer. In addition, the resulting
injected current is measured through a resistive shunt located within the injection box.
These two measured values are fed to the IED. Based on these two measured
quantities, the IED determines the stator winding resistance to ground. The resistance
value is then compared with the preset fault resistance alarm and trip levels.
The protection function can not only detect the earth fault at the generator star point,
but also along the stator windings and at the generator terminals, including the
connected components such as voltage transformers, circuit breakers, excitation
transformer and so on. The measuring principle used is not influenced by the generator
Range or value Accuracy
(100 - 1000000)Ω 5% of 1 kΩ at R
5% of 10 kΩ at 1 kΩ < R
10% of set value at 20 kΩ < R
1.00 s typically -
3.00 s typically -
(0.00 - 600.00) s ±0.2% or ±2.00 s whichever is greater
IEC 61850 IEC 60617
identification identification
STTIPHIZ
Section 7
Impedance protection
≤ 1 kΩ
f
≤ 20 kΩ
f
≤ 200 kΩ
f
ANSI/IEEE C37.2
device number
Rse< 64S
293