Products Relays


S-PRO 4000 Sub-Harmonic Protection Relay
Model 4001

S-PRO 4000 Sub-Harmonic Protection Relay

The S-PRO sub-harmonic protection relay protects generators, wind turbines, and SVC equipment from uncontrollable sub-harmonics which cause

  • Sub-Synchronous Torsional Interaction (SSTI)
  • Sub-Synchronous Control Interaction (SSCI) and
  • Ferro-resonance

The S-PRO monitors potentially harmful Sub-Synchronous Oscillation (SSO) in real time & detects Sub-Synchronous Resonance (SSR) in transmission lines with power controller interactions such as FACTS or HVDC lines, particularly those lines with series compensation and interconnected with wind farms .

Protect against sustained sub-harmonics in wind farm operations
Un-damped sub-harmonic current oscillations created by series capacitors interacting with the wind system can cause serious damage to wind turbine controllers and also to conventional generators. The wind turbine's own mechanical system interactions (tower-to-blade) can also generate sub-harmonics, which are detrimental to induction generators and transformers, and may cause resonance at the point of common coupling in the electrical grid.

The S-PRO relay detects these sub harmonic oscillations and allows the utility to monitor and protect the power system by isolating the healthy grid from sub-harmonic generation sources.

Features and Benefits

  • Provides real time processing of voltage and current signals at all Sub-harmonic frequencies in the range of 5 - 55 Hz (60 Hz system) and 5-45 Hz (50 Hz system) with a detection resolution of 0.2 Hz
  • Operating speed between 200-450ms
  • Provides incident trending to protect generators and other equipment against sustained sub-harmonics beyond normal levels that may not exceed levels that will cause SSR
  • Operations per duration settable for durations from 1-60 minutes
  • Events accumulated over a long period of time can be used to flag maintenance requirements
  • Sub-harmonic measurements monitoring through 61850 GOOSE, DNP 3 and Modbus.
  • Total Sub Harmonic Distortion (TSHD) reporting
  • 59, 27 and 50LS protection at <1.5 cycles,
  • 2nd and 5th Harmonic Blocking for reliable operation under inrush conditions
  • Flexible Communications
    • State-of-the-art communications (2 rear ports, 100BASE-TX RJ-45 or 100BASE-FX 1300 nm multimode optical with ST style connector to accommodate the industry’s latest network-based communications)
    • Ethernet ports with 2 unique MAC addresses that easily accommodate network access security needs
    • Front panel USB and 100BASE-TX RJ-45 Ethernet port interfaces (readily accommodate modern standard laptops)
  • Reduced Cost
    • Substation automation cost - includes IEC61850 protocol to display and transfer operational data via local-area network (LAN) for local HMI and wide-area network (WAN) for remote monitoring SCADA
    • Substation engineering, installation and commissioning cost and times - IEC 61850 GOOSE messages communicate high-speed information between IED’s on the substation LAN (including transfer trips, interlocking, load-shedding, and commands)
    • Product setting time - 240 x 128 LCD graphical user interface provides convenient means to check/change specific settings and parameters
  • Improved Overall Response Time
    • Expedited response to systems events (11 generic front panel LEDs can be mapped to internal elements) allowing operators to quickly identify the cause of system events
  • SPRO screen shotsEasy to Use
    • Flexible programmable logic for building customized schemes with ProLogic™ statements User-friendly,
    • Windows®-based relay setting and record analysis software
    • Enhanced DNP3.0 Level 2 SCADA communication protocol including user-selectable point lists, class support and multiple master station support
    • Exceptional fault recording capabilities with 96 s/cycle, all channels with events



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Winnipeg, Canada