The SIPROTEC Compact 7SK81 unit is a numerical motor protection relay for low power CT and VT inputs. It can perform control and monitoring functions and therefore provide the user with a cost-effective platform for power system management, that ensures reliable supply of electrical power to the customers. The ergonomic design makes control easy from the relay front panel. A large, easy-to-read display was a key design factor.

Control

The integrated control function permits control of disconnect devices, grounding switches or circuit-breakers through the integrated operator panel, binary inputs, DIGSI 4 or the control or automation system (e.g. SICAM).

Programmable logic

The integrated logic characteristics (CFC) allow the user to add own functions for automation of switchgear (e.g. interlocking) or switching sequence. The user can also generate user-defi ned messages. This functionality can form the base to create extremely flexible transfer schemes.

Operational measured value

Extensive measured values (e.g. I, V), metered values (e.g. Wp, Wq) and limit values (e.g. for voltage, frequency) provide improved system management.

Operational indication

Event logs, trip logs, fault records and statistics documents are stored in the relay to provide the user or operator with all the key data required to operate modern substations.

Motor protection

The 7SK81 relay is specifically designed to protect induction-type asynchronous motors.

Line protection

The 7SK81 units can be used for line protection of high and medium-voltage networks with grounded, low-resistance grounded, isolated or a compensated neutral point.

Transformer protection

The 7SK81 relay provides all the functions for backup protection for transformer differential protection. The inrush suppression effectively prevents unwanted trips that can be caused by inrush currents.

Backup protection

As a backup protection the 7SK81 devices are universally applicable.

Switchgear cubicles for high/medium voltage

All units are designed specifically to meet the requirements of high /medium-voltage applications. In general, no separate measuring instruments (e.g., for current, voltage, frequency, …) or additional control components are necessary.