Current protection relay PCS-987R

speedvoltageshaft rotation

Overview
Sub-synchronous oscillations (SSO) can occur when turbine-generators are connected to the power grid under certain electrical conditions (for example: transmission line series capacitors, HVDC converters, large-scale wind power). Under SSO the turbine-generator shaft system may experience torsional vibration that can cause cumulative fatigue, shaft cracks, bolt shearing or coupling damage. PCS-987R is a digital protective relay (Torsional Stress Relay, TSR) designed to monitor and protect turbine-generator shaft systems from torsional vibration risks in large thermal, nuclear and other power generation units.

Miscellaneous functions

• Current transformer supervision function (CTS)
• Voltage transformer supervision function (VTS)
• Rotational speed signal supervision (supports four rotational speed sensors, typically installed at turbine end and exciter end)
• Optical fiber communication supervision

Protective functions

• Torsional vibration modal divergence protection
• Shaft cross-section accumulative fatigue protection with alarm or trip
• Shaft section total fatigue alarm function

Technical specifications

• Model: PCS-987R
• Function: Monitoring and protection of torsional vibration in turbine-generator shaft systems
• Applications: Large-scale thermal power units, nuclear power units and other generation units subject to SSO
• Sensors: Supports four rotational speed signal sensors (typically installed at turbine end and exciter end)
• Supervision: Current transformer supervision (CTS), voltage transformer supervision (VTS), rotational speed signal supervision, optical fiber communication supervision
• Protection features: Torsional vibration modal divergence protection; shaft cross-section accumulative fatigue protection for alarm or trip; shaft section total fatigue alarm