Siemens siprotec SJ62 User Manual page 78

50N-2 Element
50-1 Element
50N-1 Element
SIPROTEC 4, 7SJ62/63/64 Handbuch
C53000-G1140-C147-A, Edition 07.2015
short safety delay 50-2 DELAY (e.g. 100 ms). For faults on the outgoing feeders the
element 50-2 is blocked. Both elements 50-1 or 51 serve as backup protection. The
pickup values of both elements (50-1 PICKUP or 51 PICKUP and 50-2 PICKUP) are
set equal. Delay time 50-1 DELAY or 51 TIME DIAL is set such that it overgrades
the delay for the outgoing feeders.
The selected time is 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 50-2 element is not required
at all, then the pickup threshold 50-2 PICKUP should be set to ∞. This setting pre-
vents tripping and the generation of a pickup message.
The pickup and delay of element 50N-2 are set at addresses 1302 and 1303. The
same considerations apply for these settings as they did for phase currents discussed
earlier.
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 50N-2 element is not
required at all, the pickup threshold 50N-2 PICKUP should be set to ∞. This setting
prevents tripping and the generation of a pickup message.
For setting the 50-1 relay element it is the maximum anticipated load current that must
be considered. Pickup due to overload should never occur, since the device, in this
mode, operates as fault protection with correspondingly short tripping times and not
as overload protection. For this reason, a setting equal to 20% is recommended for
line protection, and a setting equal to 40% of the expected peak load is recommended
for transformers and motors.
The settable time delay (address 1205 50-1 DELAY) results from the grading coor-
dination chart defined for the network.
The selected time is 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 50-1 element is not required
at all, then the pickup threshold 50-1 PICKUP should be set to ∞. This setting prevents
tripping and the generation of a pickup message.
The pickup value of the 50N-1 relay element should be set below the minimum antic-
ipated ground fault current.
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 50N–1 relay element. It
can be enabled or disabled for both the phase current and the ground current in
address 2201 INRUSH REST.. The characteristic values of the inrush restraint are
listed in Subsection "Inrush Restraint".
The delay is set at address 1305 50N-1 DELAY and should be based on system co-
ordination requirements. For ground currents in a grounded system a separate coor-
dination chart with short time delays is often used.
The selected time is 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 50N-1 element is not required
at all, the pickup threshold 50N-1 PICKUP should be set to ∞. This setting prevents
tripping and the generation of a pickup message.
2.2 Overcurrent Protection 50, 51, 50N, 51N
76