GE G60 Instruction Manual page 467

CHAPTER 5: SETTINGS
Figure 5-168: Equivalent circuit, single-point, and double-point injection
Referring to the single-point injection circuit, the magnitude of I
impact on the voltage drop across Z
written:
where
I is the current flowing due to V
G1
I is the current flowing due to V
G2
Solving for R we get:
G
For the double-point injection circuit, R
The V voltage is therefore composed of a square wave to create two levels of injection. Once the value of R
INJ
can be substituted into the V
INJ
circuit) is known through measurement then the location of the fault is simply V
as percentage of field winding from negative terminal in case of single point injection. If double point injection is used, fault
location cannot be determined. The relay displays an invalid fault location for approximately 10% for such conditions. The
fault location cannot be determined if the field voltage is zero (that is, when the generator is not running). The fault location
is displayed only when the measured field ground resistance is less than 500 KΩ. See the
Fault Protection Modules Quick Reference Guide
G60 GENERATOR PROTECTION SYSTEM – INSTRUCTION MANUAL
. Therefore if two values (V
F2
INJ1
INJ2
is defined as:
CL
equation above to determine V
for details of wiring and installation of the field ground module.
makes it evident that V
FLD INJ
and V ) are injected the following equations can be
INJ1 INJ2
. If the V voltage (refer to the single-point injection
F2 FLD
/ V . This gives the location of the fault
F2 FLD
GPM Field and Stator Ground
GROUPED ELEMENTS
cannot have a significant
Eq. 5-46
Eq. 5-47
Eq. 5-48
is known it
G
5-291
5