STP-K120

Main functions

• Transformer current differential protection function
• Overcurrent/overvoltage protection function
• Prevents misoperation from magnetizing inrush current
• Records fault events and waveforms
• 7-inch touch LCD
• Configurable simplified substation single-line diagram
• Operator-configurable LEDs
• Supports high-speed current differential protection (87HOC) or current ratio differential protection (87R) using the current difference between transformer windings
• Calculates phasors of the transformer currents and the current difference between windings
• Uses the second harmonic to prevent misoperation from magnetizing inrush current
• Blocks relay operation and prevents false alarms or misoperation based on real-time self-monitoring
• Instantaneous (50) and time (51, including definite-time) overcurrent protection for three-phase and neutral currents on both the HV and LV sides of the transformer
• Supports OLTC blocking (50B)
• Supports blocking (50B) for the sudden pressure relay
• Supports various standard inverse-time characteristic curves
• Blocks relay operation and prevents false alarms or misoperation based on continuous self-monitoring