Introduction
1.2 Application Scope
SIPROTEC, 7SJ61, Manual
C53000-G1140-C210-1, Release date 02.2008
21
1.2
Application Scope
The numerical, multi-functional SIPROTEC 4 7SJ61 is a versatile device designed for protection, control and
monitoring of busbar feeders. For line protection, the device can be used in networks with earthed, low resis-
tance earthed, isolated or compensated neutral point. It is suited for networks that are radial and supplied from
a single source or open looped networks. The device is equipped with motor protection applicable for asyn-
chronous machines of all sizes.
The device includes the functions that are necessary for protection, for monitoring of circuit breaker positions,
and control of the circuit breakers in straight bus applications or breaker-and-a-half configurations; therefore,
the devices can be universally employed. The devices also provide excellent backup facilities of differential pro-
tective schemes of lines, transformers, generators, motors, and busbars of all voltage levels.
Protective Functions
Non-directional overcurrent protection (50, 50N, 51, 51N) is the basis of the device. There are three definite
time overcurrent protective elements and one inverse time element for the phase currents and the ground cur-
rent. For inverse time overcurrent protective elements, several curves of different standards are provided. Al-
ternatively, user-defined characteristic can be programmed.
Depending on the variant ordered, the overcurrent time protection can feature breaker failure protection and
ground fault protection for high-resistence ground short-circuits and faults.
In addition to the fault protection functions already mentioned, other protective functions are available. Some
of them depend on the version of the device that is ordered. These additional functions include negative se-
quence protection (46), thermal overload protection (49) with start inhibit for motors (66/68), and motor starting
protection (48), as well as automatic reclosing (79) which allows different reclosing cycles on overhead lines.
An automatic reclosing system may also be connected externally.
A protection feature can be ordered for the detection of intermittent ground faults which detects and accumu-
lates transient ground faults.
External detectors account for ambient temperatures or coolant temperatures (by means of an external RTD-
box).
Control Functions
The device features a control function for activating and deactivating switchgears via the integrated operator
panel, the system interface, binary inputs, and the serial port using a personal computer with DIGSI.
The status of the primary equipment can be transmitted to the device via auxiliary contacts connected to binary
inputs. The present status (or position) of the primary equipment can be displayed on the device, and used for
interlocking or plausibility monitoring. The number of the operating equipment to be switched is limited by the
binary inputs and outputs available in the device or the binary inputs and outputs allocated for the switch posi-
tion indications. Depending on the primary equipment being controlled, one binary input (single point indication)
or two binary inputs (double point indication) may be used for this process.
The capability of switching primary equipment can be restricted by a setting associated with switching authority
(Remote or Local), and by the operating mode (interlocked/non-interlocked, with or without password request).
Processing of interlocking conditions for switching (e.g. switchgear interlocking) can be established with the aid
of integrated, user-configurable logic functions.