Setting Notes - Siemens SIPROTEC 7SK80 Manual
Motor protection
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Functions
2.11 Ground Fault Protection 64, 67N(s), 50N(s), 51N(s)
2.11.4
Setting Notes
General Settings
During configuration of the protection function (Section 2.1.1, under address 131 Sens. Gnd Fault it was
determined with which parameters the ground fault detection is functioning. If address Sens. Gnd Fault =
Definite Time is selected, then the definite-time parameters are available. If Sens. Gnd Fault = User
Defined PU is selected, a user-specified Curve can be used for the overcurrent elements 50Ns-1 or 51Ns.
The superimposed high-current element 50Ns-2 is available in all these cases. If this function is not required,
then Disabled is set. The user characteristics are only available, if the standard measurement procedure cos
ϕ / sin ϕ has been set at address 130.
The characteristic for determining the direction is set at address 130 S.Gnd.F.Dir.Ch. It is optional to select
either the standard measurement method cos ϕ / sin ϕ or the V0/I0 ϕ mea. with one sector character-
istic.
At address 3101 Sens. Gnd Fault, the function ON or OFF can be set to either ON with GF log or Alarm
Only. If settings ON and ON with GF log are applied, tripping is also possible, otherwise a fault log is created.
A ground fault log is created for ON with GF log and Alarm Only. Setting ON with GF log is only
available if characteristic V0/I0 ϕ mea. has been selected at address 130 S.Gnd.F.Dir.Ch.
The parameters 3111 T-DELAY Pickup and 3130 PU CRITERIA are only visible if the standard measure-
ment method cos ϕ / sin ϕ has been selected when setting the direction characteristic. The ground fault
is detected and reported when the displacement voltage was sustained a certain time T-DELAY Pickup).
Address 3130 PU CRITERIA specifies whether ground fault detection is enabled only for pickups of V
(Vgnd AND INs) or as soon as one of the two has picked up (Vgnd OR
I
NS
The pickup can be stabilized for ground fault protection with definite time curve by a settable dropout time delay
(address 3121 50Ns T DROP-OUT). This facility is used in power systems with intermittent faults. Used to-
gether with electro-mechanical relays, it allows different dropout responses to be adjusted and time grading of
digital and electro-magnetic relays to be implemented. The setting depends on the dropout time delay of the
electro-magnetic relay. If no coordination is required, the preset value (zero = no dropout time delay) remains.
Note
Please not that under address 213 VT Connect. 3ph the connection type of the voltage transformer Van,
Vbn, Vcn or Vab, Vbc, VGnd must be set. Additionally, adjustment factor Vph / Vdelta for the displace-
ment voltage must be set correctly under address 206. Depending on the type of connection of the current
transformer, the primary and secondary rated current in the ground path must be set under address 217 and
218, and, if required, the primary and secondary rated current of the second ground current transformer must
be set under address 238 and 239.
Overcurrent Elements Definite Time/Inverse Time
A two-element current/time Curve can be set at addresses 3113 to 3120. These elements operate with the
amounts of the ground current. They are therefore only useful where the magnitude of the ground current and
maybe its direction can be used to specify the ground fault. This may be the case for grounded systems (solid
or low-resistant) or on electrical machines connected to the busbar of an ungrounded power system, when in
case of a network ground fault the machine supplies only a negligible ground fault current across the measure-
ment location, which must be situated between the machine terminals and the network, whereas in case of a
machine ground fault the total ground fault current produced by the total network is available.
190
INs).
SIPROTEC, 7SK80, Manual
E50417-G1140-C344-A4, Release date 08.2010
and
N
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