Siemens siprotec SJ62 User Manual page 216

Trip Time Delay
Determination of
Direction
SIPROTEC 4, 7SJ62/63/64 Handbuch
C53000-G1140-C147-A, Edition 07.2015
When changing to primary values, the following applies:
Motor with the parameterization:
Parameter 213 VT Connect. 3ph
Parameter 3110 64-1 VGND
When changing to primary values, the following applies:
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 assuming that
ground fault detection is configured to perform tripping (address 3101 Sens. Gnd
Fault = ON) and moreover address 3130 PU CRITERIA is configured Vgnd OR
INs. The tripping delay is then set at address 3112 64-1 DELAY. It is important to
note that the total tripping time consists of the displacement voltage measurement
time (about 50 ms) plus the pickup time delay (address 3111 T-DELAY Pickup) plus
the tripping time delay (address 3112 64-1 DELAY).
Addresses 3115 to 3126 are for direction determination.
The direction of the definite high-set element 67Ns-2 is set at address 3115 67Ns-2
DIRECT and may be configured Forward or Reverse or Non-Directional, i.e. to
both directions. The direction of the definite time high-set element 67Ns-1 can be set
at address 3122 67Ns-1 DIRECT. = Forward or Reverse or Non-Directional,
i.e. to both directions.
Current value RELEASE DIRECT. (address 3123) is the release threshold for direc-
tional determination. It is based on the current components which are perpendicular
to the directional limit lines. The position of the directional limit lines themselves are
based on the settings entered at addresses 3124 and 3125.
The following is generally valid for determination of direction during ground faults: The
pickup current INs dir (=RELEASE DIRECT. address 3123) must be set as high as
possible to avoid a false pickup of the device provoked by asymmetrical currents in
the system and by current transformers (especially in a Holmgreen-connection).
If direction determination is used in conjunction with one of the current elements dis-
cussed above (50Ns-1 PICKUP, addresses 3117 ff, or 51Ns PICKUP, addresses
3119 ff), a value for address RELEASE DIRECT. is only significant if it is less than or
equal to the pickup value mentioned above.
A corresponding message (reverse, forward, or undefined) is issued upon direction
determination. To avoid chatter for this message resulting from sharply-varying ground
fault currents, a dropout delay RESET DELAY, entered at address 3126, is initiated
2.12 Ground Fault Protection 64, 67N(s), 50N(s), 51N(s)
= Van, Vbn, Vcn
= 40 V
214