Technical Parameters Parameter Category Specification Compatible Breaker Series ABB SACE Tmax XT Molded Case Circuit Breakers (MCCBs) - Fixed and Plug-in versions. (Also compatible with some earlier T, TL, and XT1 breakers with appropriate adapters). Rated Frame Current (In) Must match the Tmax XT frame size. Compatible with multiple frames, typically from XT1 (160A) to XT4 (630A). The PR121/P is scaled; its settings adjust based on the installed breaker's frame size. Power Supply Self-powered from the breaker's internal current sensors. No external auxiliary power required for protection and basic functions. Core Protection Functions • Long-time Protection (L) Adjustable Settings: - Ir (Rated Current): 0.4 to 1.0 x In (in steps). - tr (Time Delay): Adjustable via selection of I²t inverse-time curves (e.g., Curve 1, 2, 3). • Short-time Protection (S) Adjustable Settings: - Isd (Short-time Current): 1.5 to 10 x Ir (in steps). - tsd (Short-time Delay): Adjustable in seconds (e.g., 0.1s or 0.2s) or can be set to OFF. • Instantaneous Protection (I) Adjustable Settings: - Ii (Instantaneous Current): 2 to 14 x In, or can be set to OFF. • Ground-Fault Protection (G) Available. Adjustable Settings: - Ig (Ground Fault Current): 0.2 to 1.0 x In (or fixed steps like 100A, 200A...). - tg (Ground Fault Delay): Adjustable in seconds (e.g., 0.1s, 0.2s, 0.3s) or INST (instantaneous). Measurement & Display (/P Feature) • Display Backlit LCD display (monochrome). • Measured Values Real-time display of: Phase currents (L1, L2, L3), Neutral current (if sensor present), Max current, % Load. Communication Optional. Requires an add-on communication module (e.g., Ekip Com module) to enable Modbus RTU, Profibus DP, or DeviceNet. Diagnostics & Logging • Pre-alarms for overload (e.g., 90%, 105%). • Trip Cause Indication on display (e.g., L, S, I, G). • Last Fault Value recording. Configuration Via front keypad or via ABB Ekip Connect PC software (requires optional USB or communication module). Ambient Temperature -25°C to +70°C (Operating) Standards IEC 60947-2, UL 489 Key Feature Selectivity (Coordination): The adjustable Isd and tsd (S function) allow for time-current selectivity with downstream breakers. The adjustable Ii (I function) can be used for current selectivity.