Siemens 7SJ81 Siprotec Compact Overcurrent Protection

Siemens Siprotec Compact 7SJ81 Overcurrent Protection Relay

The SIPROTEC Compact 7SJ81 Overcurrent Protection Relay provides 4 low-power current transformer inputs and optionally 3 low-power voltage transformer inputs. With the same low-power current transformer (LPCT) a wide range of primary rated line currents can be covered. Objects with rated currents in the range from 20 A to 2500 A can be protected when using low-power current transformers.The following low-power current transformer ratios are suitable for the following primary current operating rangesHighlights-300 A/225 mV for a primary operating current range of 60 A to 630 A-600 A/225 mV for a primary operating current range of 120 A to 1250 A-1250 A/225 mV for a primary operating current range of 250 A to 2500 A-100 A/225 mV for a primary operating current range of 20 A to 200 ASIPROTEC 7SJ81 is a multi-functional motor protection relay. It is designed for the protection of asynchronous motors of all sizes.

The relays have all the functionality to be applied to a backup relay to a transformer differential relay.The relay provides numerous functions to respond flexibly to the system requirements and to deploy the invested capital economically. Examples for this are exchangeable interfaces, flexible protection functions and the integrated automation level (CFC). Freely assignable LEDs and a six-line display ensure a unique and clear display of the process states. In combination with up to 9 function keys, the operating personnel can react quickly and safely in any situation. This guarantees a high operational reliability.

7SJ81 Overcurrent Protection Relay

Highlights:

• Use inputs for low-power CTs and VTs according to IEC 61869-6 (formerly IEC 60044-7 and IEC 60044-8)
• Remove terminal blocks easily
• Set binary input thresholds using DIGSI (3 stages)
• Operate 9 programmable function keys
• View information on a 6-line display
• Replace the buffer battery from the front
• Access a USB front port
• Utilize 2 additional communication ports
• Use an integrated switch for cost-effective and redundant optical Ethernet rings
• Support Ethernet redundancy protocols such as RSTP, PRP, and HSR for high availability
• Enable relay-to-relay communication via Ethernet using IEC 61850 GOOSE
• Achieve millisecond-accurate time synchronization through Ethernet with SNTP

The SIPROTEC Compact 7SJ81 relays protect line and feeder applications in high- and medium-voltage networks with grounded, low-resistance grounded, isolated, or compensated neutral points.

Then, The relays provide all the functions required to operate as backup protection for a transformer differential relay. The SIPROTEC Compact 7SJ81 delivers high reliability and comprehensive functionality by combining proven algorithms with newly developed hardware. Field experience with nearly 1,000,000 SIPROTEC devices proves its reliability. However, The relay offers numerous functions to respond flexibly to system requirements and to use the invested capital efficiently. Examples for this are exchangeable interfaces, flexible protection functions and the integrated automation level (CFC). Freely assignable LEDs and a six-line display ensure a unique and clear display of the process states. In combination with up to 9 function keys, the operating personnel can react quickly and safely in any situation. This guarantees a high operational reliability.

CONTROL FUNCTIONS/PROGRAMMABLE LOGIC

• Commands for the ctrl. of CB, disconnect switches (isolators/isolating switches)
• Control through keyboard, binary inputs, DIGSI 4 or SCADA system
• User-defined PLC logic with CFC (e.g. interlocking)

MONITORING FUNCTIONS

• Operational measured values V, I, f
• Energy metering values Wp, Wg
• Circuit-breaker wear monitoring
• Minimum and maximum values
• Trip circuit supervision (74TC)
• Fuse failure monitor
• 8 oscillographic fault records

Therefore, Perfectly suited for protection in distribution systems and industry, with minimal space requirement. Moreover,  SIPROTEC Compact devices provide a comprehensive range of functions in a surprisingly compact and space-saving housing. Whether as main or as backup protection, a single SIPROTEC Compact device provides protection functionality for every conceivable fault. And it can do even more – it supports the control, automation, and monitoring functions in the substation.