Specifications

Line Differential Protection SIPROTEC 7SD80
3/7SIPROTEC Compact · SIEMENS SIP 3.01 · Edition 3
Trip circuit supervision (ANSI 74TC)
One or two binary inputs can be used for monitoring the
circuit-breaker trip coil including its incoming cables. An alarm
signal is generated whenever the circuit is interrupted.
Flexible protection functions
SIPROTEC 7SD80 enables the user to easily add up to 20
additional protective functions. Parameter defi nitions are
used to link standard protection logic with any chosen
characteristic quantity (measured or calculated quantity).
The standard logic consists of the usual protection elements
such as the pickup set point, the set delay time, the TRIP
command, a block function, etc. The mode of operation for
current, voltage, power and power factor quantities can be
three-phase or phase-selective. Almost all quantities can be
operated with ascending or descending pickup stages (e.g.
under and over voltage). All stages operate with protection
priority or speed.
dV/dt
SIP-0002.en.ai
Fig. 3/4 Flexible protection functions
Lockout (ANSI 86)
All binary output statuses can be memorized. The LED reset
key is used to reset the lockout state. The lockout state is also
stored in the event of supply voltage failure. Reclosure can
only occur after the lockout state is reset.
Thermal overload protection (ANSI 49)
To protect cables, an overload protection function with an
integrated warning/alarm element for temperature and
current can be used. The temperature is calculated using
a thermal homogeneous body model (per IEC 60255-8), it
considers the energy entering the equipment and the energy
losses. The calculated temperature is constantly adjusted
according to the calculated losses. The function considers
loading history and fl uctuations in load.
Overvoltage protection (ANSI 59)
The two-element overvoltage protection detects unwanted
network and machine overvoltage conditions. The function
can operate either with phase-to-phase, phase-to-ground,
positive phase-sequence or negative phase-sequence
voltage. Three-phase and single-phase connections are
possible.
Undervoltage protection (ANSI 27)
The two-element undervoltage protection provides protec-
tion against dangerous voltage drops (especially for electric
machines). Applications include the isolation of generators
or motors from the network to avoid undesired operating
conditions and a possible loss of stability. Proper operating
conditions of electrical machines are best evaluated with
the positive-sequence quantities. The protection function is
active over a wide frequency range (± 10 % rated frequency).
Even when falling below this frequency range the function
continues to work, however, with decreased accuracy. The
function can operate either with phase-to-phase, phase-
to-ground or positive phase-sequence voltage, and can be
monitored with a current criterion. Three-phase and single-
phase connections are possible.
Frequency protection (ANSI 81O/U)
Frequency protection can be used for overfrequency and un-
derfrequency protection. Electric machines and parts of the
system are protected from unwanted frequency deviations.
Unwanted frequency changes in the network can be detected
and the load can be removed at a specifi ed frequency set-
ting. Frequency protection can be used over a wide frequen-
cy range (± 10 Hz rated frequency). There are four elements
(individually set as overfrequency, underfrequency or OFF)
and each element can be delayed separately. Blocking of the
frequency protection can be performed by activating a binary
input or by using an undervoltage element.
Customized functions (ANSI 32, 51V, 55 etc.)
Additional functions can be implemented using CFC or
fl exible protection functions. Typical functions include
reverse power, voltage controlled overcurrent, phase angle
detection, and zero-sequence voltage detection.
Fast current monitoring
and further monitoring functions
SIPROTEC 7SD80 incorporates comprehensive monitoring
func-tions for hardware and software. Monitoring comprises
the measuring circuits, the analog-digital conversion, the
protection data communication connection the internal
supply voltages, the memories and the software sequence
(watchdog).
Application sheets
SIP-0002.en.EPS.pdf
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