What are the applications of SIPROTEC 4 7SJ62 Multifunction Protection Relay?

 

SIPROTEC 4 7SJ62 Multifunction Protection Relay

The SIPROTEC 4 7SJ62 relays can be used for line protection of high and medium voltage networks with earthed (grounded), low-resistance grounded, isolated, or compensated neutral point. With regard to motor protection, the SIPROTEC 4 7SJ62 is suitable for asynchronous machines of all sizes. The relay performs all functions of backup protection supplementary to transformer differential protection. 7SJ62 is featuring "flexible protection functions". Up to 20 protection functions can be added according to individual requirements. 

Thus, for example, a rate-of-frequency-change protection or reverse power protection can be implemented. 

The relay provides control of the circuit-breaker, further switching devices, and automation functions. The integrated programmable logic (CFC) allows the user to implement their own functions, e. g. for the automation of switchgear (interlocking). The user is also allowed to generate user-defined messages. The flexible communication interfaces are open for modern communication architectures with control systems.

Schematic

The SIPROTEC 4 7SJ62 unit is a numerical protection relay that also performs control and monitoring functions and therefore supports the user in cost-effective power system management, and ensures a reliable supply of electric power to the customers. 

Local operation has been designed according to ergonomic criteria. A large, easy-to-read display was a major design aim.

Control 

The integrated control function permits control of disconnect devices, grounding switches, or circuit-breakers via the integrated operator panel, binary inputs, DIGSI 4, or the control and protection system (e.g. SICAM). The present status (or position) of the primary equipment can be displayed, in the case of devices with graphic display. A full range of command processing functions is provided. 

Programmable logic 

The integrated logic characteristics (CFC) allow the user to implement their own functions for automation of switchgear (interlocking) or a substation via a graphic user interface. The user can also generate user-defined messages. 

Line protection 

The 7SJ62 units can be used for line protection of high and medium-voltage networks with earthed (grounded), lowresistance grounded, isolated or compensated neutral point.

Read: Guide for Protective Relay Applications to Power Transformers: Fuse Protection

Synchro-check 

In order to connect two components of a power system, the relay provides a synchro-check function which verifies that switching ON does not endanger the stability of the power system. 

Motor protection 

When protecting motors, the 7SJ62 relay is suitable for asynchronous machines of all sizes. 

Transformer protection The relay performs all functions of backup protection supplementary to transformer differential protection. The inrush suppression effectively prevents tripping by inrush currents. The high-impedance restricted ground-fault protection detects short-circuits and insulation faults on the transformer. 

Backup protection 

The 7SJ62 can be used universally for backup protection. Flexible protection functions By configuring a connection between a standard protection logic and any measured or derived quantity, the functional scope of the relays can be easily expanded by up to 20 protection stages or protection functions.

 Metering values

Extensively measured values, limit values, and metered values permit improved system management.

Reference: 

• Overcurrent Protection / 7SJ62 | Download
• Publisher: Siemens