ABB 615 Series - Page 436

V
3H_T
V
3H_N
No load
No load
Full load
Full load
Terminal Neutral
Normal operation
No load
Full load
Terminal Neutral
Fault at neutral
No load
Full load
Terminal Neutral
Fault at terminal
V
3H_T
V
3H_N
V
3H_T
V
3H_N
GUID-B85C3CE6-129D-4B09-8B77-2FE59D9DA1B9 V1 EN
Figure 207: Typical example of the third-harmonic voltage measured at the generator
neutral and terminals under different conditions
The operating equation of the protection is described in the following equation.
V V V
3 3 3
0
H T H N H N
Beta
_ _ _
+ − ⋅ =
GUID-50A69B54-0D20-45BE-92BB-DE939C62A1C5 V1 EN (Equation 50)
The third harmonic voltages
V
3H T_
and
V
3H N_
are the phasor with its real and imaginary
parts.
V
3H T_
is approximately in the opposite direction to that of the
V
3H N_
, however the
actual no-fault angle between those two phasors depends on the type of generator
Section 4 1MAC059074-MB A
Protection functions
430 615 series ANSI
Technical Manual