Siemens SIPROTEC 7SK80 Manual page 193

Example:
Parameter 202
Parameter 203
Parameter 206
Parameter 213
Parameter 3109
The following applies when switching to primary values:
With the following configuration
Parameter 213
Parameter 3110
the following applies when switching to primary values:
With regard to a ground fault in a ungrounded or resonant-grounded system, nearly the entire displacement
voltage appears at the device terminals, therefore the pickup setting is not critical, and typically lies between
30 V and 60 V (for 64-1 VGND with a standard V0-connection) or 50 V and 100 V (for 64-1 VGND). Large fault
resistances may require higher sensitivity (i.e. a lower pickup setting).
With regard to a grounded system, a more sensitive (lower) pickup value may be set, but it must be above the
maximum anticipated displacement voltage during normal (unbalanced) system operation.
Pickup of just the voltage element may initiate time delayed tripping assumed that ground fault detection is con-
figured to perform tripping (address 3101 Sens. Gnd Fault = ON or ON with GF log) and moreover
address 3130 PU CRITERIA is configured Vgnd OR
64-1 DELAY. It is important to note that the total tripping time consists of the displacement voltage measure-
ment time (about 50 ms) plus the pickup time delay (address 3111 T-DELAY Pickup) plus the tripping time
delay (address 3112 64-1 DELAY).
Direction Determination for cos-ϕ/ sin-ϕ
Addresses 3115 to 3126 are important for direction determination.
Address 3115 67Ns-2 DIRECT determines the direction of the definite high-set current element 50Ns-2 and
can be set to either Forward or Reverse or Non-Directional, i.e. to both directions. The direction of the
current element 50Ns-1 or or 51Ns can be set to Forward or Reverse or Non-Directional, i.e. to both
directions, at address 3122 67Ns-1 DIRECT..
The elements operate non-directional for capacitive voltage measurement and for voltage connection types
where no measurement or calculation of V
Current value RELEASE DIRECT. (address 3123) is the release threshold for directional determination. It is
based on the current components which are perpendicular to the directional limit lines. The position of the di-
rectional limit lines themselves are based on the settings entered at addresses 3124 and 3125.
The following applies to the determination of direction during ground faults: The pickup current 3I0 DIR.
(=RELEASE DIRECT. address 3123) must be set as high as possible to avoid false pickup of the device pro-
voked by asymmetrical currents in the system and by current transformers (especially in the Holmgreen-con-
nection).
SIPROTEC, 7SK80, Manual
E50417-G1140-C344-A4, Release date 08.2010
Vnom PRIMARY
Vnom SECONDARY
Vph / Vdelta
VT Connect. 3ph
64-1 VGND
VT Connect. 3ph
64-1 VGND
or 3V
N
2.11 Ground Fault Protection 64, 67N(s), 50N(s), 51N(s)
= 12 kV
= 100 V
= 1.73
= Vab, Vbc, VGnd
= 40 V
= Van, Vbn, Vcn
= 40 V
INs. The tripping delay is then set at address 3112
is possible. Section 2.1.3.2 gives information on this topic.
0
Functions
193