7SK81 Motor Protection Relay

Product Description

The SIPROTEC Compact 7SK81 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 of 40 A to 5000 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 ranges:

• 100A/225mV for a primary operating current range of 40A 600A
• 50A/22.5mV for a primary operating current range of 200A 3000A
• 400A/225mV for a primary operating current range of 200A 2500A
• 100A/22.5mV for a primary operating current range of 400A 5000A
  

The SIPROTEC 7SK81 is a multi-functional motor protection relay. It is designed for protection of asynchronous motors of all sizes. The relays have all the required functions to be applied as 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.

Highlights:

• Inputs for low power VTs and CTs according IEC 61869-6 (formerly IEC 60044-7 and IEC 60044-8)
• Removable terminal blocks
• Binary input thresholds settable using DIGSI (3 stages)
• 9 programmable function keys
• 6-line display
• Buffer battery exchangeable from the front
• USB front port
• 2 additional communication ports
• Integrated switch for low-cost and redundant optical Ethernet rings
• Ethernet redundancy protocols RSTP, PRP and HSR for highest availability
• Relay-to-relay communication through Ethernet with IEC 61850 GOOSE
• Millisecond-accurate time synchronization through Ethernet with SNTP