Siemens siprotec SJ62 User Manual page 108

Quantity Selection
for the Direction
Determination for
the Ground Direc-
tional Element
67-2 Directional
High-set Element
(Phases)
67N-2 Directional
High-set Element
(Ground)
67-1 Directional
Overcurrent
Element (Phases)
SIPROTEC 4, 7SJ62/63/64 Handbuch
C53000-G1140-C147-A, Edition 07.2015
Parameter 1617 67N POLARIZAT. can be set to specify whether direction determi-
nation is accomplished from the zero sequence quantities, the ground quantities
(with VN and IN) or the negative sequence quantities (with V2 and I2) in the
ground directional element. The first option is the preferential setting; the latter should
be selected if there is the risk of the zero sequence voltage becoming extremely small
due to unfavorable zero sequence impedance or a parallel line influencing the zero se-
quence system.
The pickup and delay of element 67-2 are set at addresses 1502 and 1503. For set-
ting, the same considerations apply as did for the non-directional time overcurrent pro-
tection in Section 2.2.10.
The selected time is only an additional time delay and does not include the operating
time (measuring time, dropout time). The delay can be set to ∞. After pickup the
element will then not trip. Pickup, however, will be signaled. If the 67-2 element is not
required at all, the pickup value 67-2 PICKUP should be set to ∞. For this setting,
there is neither a pickup signal generated nor a trip.
The pickup and delay of element 67N-2 are set at addresses 1602 and 1603. The
same considerations apply for these settings as did for phase currents discussed ear-
lier.
The selected time is only an additional time delay and does not include the operating
time (measuring time, dropout time). The delay can be set to ∞. After pickup the
element will then not trip. Pickup, however, will be signaled. If the 67N-2 element is not
required at all, then the pickup value 67N-2 PICKUP should be set to ∞. This setting
prevents from tripping and the generation of a pickup message.
The pickup value of the 67-1 relay element 1504 67-1 PICKUP should be set above
the maximum anticipated load current. Pickup due to overload should never occur,
since the device in this operating mode operates as short circuit protection with corre-
spondingly short tripping times and not as overload protection. For this reason, lines
are set to approx. 20% above the maximum expected (over)load and transformers and
motors to approx. 40%.
If the relay is used to protect transformers or motors with large inrush currents, the
inrush restraint feature of 7SJ62/63/64 may be used for the 67-1 relay element (for
more information see margin heading "Inrush Restraint").
The delay for directional elements (address 1505 67-1 DELAY) is usually set shorter
than the delay for non-directional elements (address 1205) since the non-directional
elements overlap the directional elements as backup protection. It should be based on
the system coordination requirements for directional tripping.
For parallel transformers supplied from a single source (see "Usecases"), the delay of
elements 67-1 DELAY located on the load side of the transformers may be set to 0
without provoking negative impacts on selectivity.
The selected time is only an additional time delay and does not include the operating
time (measuring time, dropout time). The delay can be set to ∞. After pickup the
element will then not trip. Pickup, however, will be signaled. If the 67-1 element is not
required at all, the pickup value 67-1 PICKUP should be set to ∞. This setting pre-
vents from tripping and the generation of a pickup message.
2.3 Directional Overcurrent Protection 67, 67N
106