Technical data

Siemens SIP · 2008
12 Motor Protection / 7SK80
12
12/12
Protection functions
Available inverse-time characteristics
Characteristics acc. to ANSI/IEEE IEC 60255-3
Inverse
••
Short inverse
•
Long inverse
••
Moderately inverse
•
Very inverse
••
Extremely inverse
••
Time-overcurrent protection
(ANSI 50, 50N, 51, 51N)
This function is based on the phase-
selective measurement of the three phase
currents and the ground current (four
transformers). Three definite-time over-
current protection elements (DMT) are
available both for the phase and the
ground elements. The current threshold
and the delay time can be set in a wide
range. Inverse-time overcurrent protection
characteristics (IDMTL) can also be se
-
lected and activated.
Reset characteristics
Time coordination with electromechanical
relays are made easy with the inclusion
of the reset characteristics according to
ANSI C37.112 and IEC 60255-3 /BS 142
standards. When using the reset character
-
istic (disk emulation), the reset process is
initiated after the fault current has disap
-
peared. This reset process corresponds to
the reverse movement of the Ferraris disk
of an electromechanical relay (disk emula
-
tion).
Inrush restraint
The relay features second harmonic re
-
straint. If second harmonic content is
detected during the energization of a trans
-
former, the pickup of non-directional and
directional elements are blocked.
Construction and hardware
Connection techniques and
housing with many advantages
The relay housing is 1/6 of a 19" rack. The
housing is thus identical in size to the 7SJ50
and 7SJ60 relays that makes replacement
very easy. The height is 244 mm (9.61").
Pluggable current and voltage terminals
allow for pre-wiring and simplify the ex
-
change of devices. CT shorting is done in
the removable current terminal block.
It is thus not possible to open-circuit a
secondary current transformer.
All binary inputs are independent and the
pick-up thresholds are settable using soft
-
ware settings (3 stages). The relay current
transformer taps (1 A/5 A) are new soft
-
ware settings. Up to 9 function keys can be
programmed for predefined menu entries,
switching sequences, etc. The assigned
function of the function keys can be shown
in the display of the relay.
Fig. 12/8 7SK80 Front view, rear view, terminals
Cold load pickup/dynamic setting change
The pickup thresholds and the trip times
of the directional and non-directional
time-overcurrent protection functions can
be changed via binary inputs or by setable
time control.
Current terminal
block
Voltage terminal
block
LSP2876.tif
LSP2877.tif
LSP2878.tif
Illuminated 6-line display
8 programmable LEDs
Numerical key pad/9 function keys
Control keys
Standard battery exchangeable from the front
LSP2885.tif
Navigation keys
USB front port