The Siemens SIPROTEC 7SJ8041 is a compact digital multifunction protection relay designed for feeder, transformer, and motor protection in medium-voltage distribution networks. It integrates overcurrent (50/51), directional overcurrent (67/67N), earth fault (50N/51N/67Ns), voltage (27/59), frequency (81O/U), thermal overload (49), negative sequence (46), circuit breaker failure (50BF), and auto-reclose (79) protection functions in a single device. The unit features 4 CT inputs (1A/5A selectable), 3 PT inputs (100–208V), 8–11 programmable binary inputs, and 6–8 relay outputs. Communication options include Ethernet for DIGSI 4 configuration, Modbus RS485, and optional IEC 61850 with GOOSE messaging. A 6-line backlit LCD, 9 programmable function keys, and front USB port simplify local operation and commissioning. Built-in fault recording (8 records), CB wear monitoring, energy metering, and programmable CFC logic make it suitable for utility substations, industrial power distribution, and renewable energy applications.
Q: What protection functions does the 7SJ8041 support?
A: The 7SJ8041 supports overcurrent (50/51), directional overcurrent (67/67N), earth fault (50N/51N, 67Ns), voltage (27/59), frequency (81O/U), thermal overload (49), negative sequence (46), CB failure (50BF), auto-reclose (79), synchrocheck (25), fault locator (21FL), and power direction (32) protection.
Q: What communication protocols are available?
A: Standard interfaces include Ethernet RJ45 for DIGSI 4 configuration and Modbus RS485. Optional IEC 61850 with GOOSE messaging and redundant Ethernet is available.
Q: What are the auxiliary voltage options?
A: 60–250V DC or 115/230V AC auxiliary power supply.
Q: How many binary inputs and outputs does it have?
A: 8–11 freely programmable binary inputs and 6–8 command relay outputs (1 NO each), depending on the specific variant.
Q: Can the 7SJ8041 be used for motor protection?
A: Yes. With thermal overload (49), negative sequence (46), undercurrent (37), and start-up supervision, it provides comprehensive motor protection in addition to feeder protection.
Q: Is IEC 61850 supported?
A: Yes, optionally. The device supports IEC 61850 with GOOSE messaging over Ethernet, including redundant communication paths and SNTP time synchronization.
Q: How is the relay configured?
A: Configuration is done via Siemens DIGSI 4 software through the front USB port or Ethernet interface. The device also supports CFC-based user-defined programmable logic.
