Siemens siprotec 7SA6 User Manual

Functions
6-417SA6 Manual
C53000-G1176-C133-1
6.2.2.6 Information Overview
6.2.3 Calculation of the Impedances
6.2.3.1 Method of Operation
A separate measuring system is provided for each of the six possible impedance loops
L1–E, L2–E, L3–E, L1–L2, L2–L3, L3–L1. The phase-earth loops are evaluated when
an earth fault detection according to section 6.2.1 is recognized and the phase current
exceeds a settable minimum value 0LQLPXP,SK! (address ). The phase-
phase loops are evaluated when the phase currents in both of the affected phases
exceed the minimum value 0LQLPXP,SK!.
A jump detector synchronizes all the calculations with the fault inception. If a further
fault occurs during the evaluation, the new measured values are immediately used for
the calculation. The fault evaluation is therefore always done with the measured
values of the current fault condition.
Phase–Phase
Loops
To calculate the phase-phase loop, for instance during a two-phase fault L1–L2
(Figure 6-22), the loop equation is:
where
U
, I are the (complex) measured values and
Z
= R+ jX is the (complex) line impedance.
The line impedance is computed to be
F.No. Alarm Comments
3781 Dis.TimeOut Tfw DistanceTime Out Forward PICKUP
3782 Dis.TimeOut Tnd DistanceTime Out Reverse/Non-dir. PICKUP
3695 Dis Pickup ϕ L1 Dist.: Phi phase L1 Pickup
3696 Dis Pickup ϕ L2 Dist.: Phi phase L2 Pickup
3697 Dis Pickup ϕ L3 Dist.: Phi phase L3 Pickup
I
L1
Z
L
I
L2
Z
L
U
L1–E
U
L2–E
–=
⋅
–
⋅
Z
L
U
L1–E
U
L2–E
–
I
L1
I
L2
–
--------------------------------------=

Siemens siprotec 7SA6 Specifications

General

Brand	Siemens
Model	siprotec 7SA6
Category	Relays
Language	English