1. What is the SHNIS-II device used for? The SHNIS-II is an Earth-Fault Feeder Selection Device for non-effectively earthed systems. It identifies the faulty feeder during single-phase earth faults and can support tripping, feeder rotation, and post-acceleration tripping functions.
2. Which power systems is it suitable for?
It is designed for medium-voltage networks where the neutral point is isolated or earthed through an arc-suppression coil, typically below 110 kV.
3. How does it improve fault selection accuracy?
The device uses a combined steady-state and transient algorithm with fuzzy information fusion. Each feeder receives a comprehensive fault credibility coefficient, which helps maintain high accuracy even under complex fault conditions.
4. Can it detect different types of earth faults?
Yes. It can identify direct earth faults, resistive earth faults, arcing earth faults, and other complex fault types.
5. Does it support fault recording?
Yes. It provides full-process fault recording. The device can record data before and after fault events and support continuous recording for up to 2 hours.
6. What communication and time-synchronization features are supported?
It supports IEC 61850 / DL/T 860 substation communication and high-precision time synchronization via IRIG-B and SNTP. IRIG-B synchronization accuracy is within ±1 μs.
7. What are the typical input configurations?
The standard configuration supports 20 zero-sequence current channels, 32 digital inputs, and 48 digital outputs. Bus voltage is also monitored for earth-fault analysis.
8. What are the operating environment requirements?
The device can operate at altitudes up to 4,000 m, with an operating temperature range of -10 °C to 50 °C and humidity from 5% to 95%.
9. How reliable is the fault selection performance?
The first fault selection accuracy is ≥95%. When the delay setting is not greater than 0.5 s, the overall operating time is not greater than 540 ms.
10. Does the device meet international or industry standards?
The device is designed in accordance with relevant Chinese power industry standards and international references, including DL/T 872-2016, Q/CSG 1203068-2019, IEC 61850, and related EMC and insulation test standards.
11. What power supply options are available?
It supports DC 110 V / 220 V and AC 220 V power supplies, with allowable voltage fluctuations typically within -20% to +15% for DC and -20% to +10% for AC.
12. What after-sales support is provided?
After delivery, technical personnel can assist with installation, commissioning, and training. Remote support and on-site service are available according to customer agreements.