Technical Parameters
Parameter Category Specification
Product Family / Type Self-Powered Three-Phase Current Monitoring Relay
Function Protection against: Phase Loss, Phase Reversal, Current Asymmetry (Unbalance).
Standard Compliance IEC 60947-1, IEC 60947-5-1
Power Supply Self-powered from the monitored current transformers (CTs). No external auxiliary voltage required.
Rated Current Input (In) 1 A AC (This is defined by the -600- in the type code. 600 = 1A; 500 = 5A).
Operating Range 0.1 A to 1.3 A AC.
Frequency 50 / 60 Hz.
Monitoring Functions & Settings
• Phase Loss Detection Detects if any phase current falls below the threshold setting.
• Phase Asymmetry (Unbalance) Detects imbalance between phase currents. Adjustable tripping threshold (e.g., 20% to 70% of asymmetry).
• Phase Sequence Monitors for correct phase rotation (e.g., L1-L2-L3). Trips on reversal.
• Threshold Setting (I<) Adjustable via rotary switch (typically 0.15 - 0.95 x In) to define the minimum current level.
• Response Time Fixed, typically around 0.1 to 1 second.
Output Contact
• Type 1 Changeover (CO) contact (SPDT: 1 NO + 1 NC).
• Rated Operational Current (Ie) 6 A AC-15 / 0.5 A DC-13.
• Utilization Category AC-15: 230V, 6A; DC-13: 24V, 0.5A.
Binary Input 1 Reset/Start Input (Terminal A1). A voltage pulse (24-240V AC/DC) is required to close the output relay after a fault or power-up.
Indications 2 LEDs:
- Green (On) : Power OK, correct phase sequence, currents above threshold.
- Red (Trip) : Fault condition (Phase Loss, Reversal, or Asymmetry).
Connection Screw-clamp terminals for:
- 3 Phase Current Inputs (L1, L2, L3).
- Output Contact (13, 14, 23).
- Reset Input (A1, A2).
Electrical Life ≥ 100,000 cycles (at rated load).
Isolation Reinforced insulation between current circuits, output contact, and reset input.
Operating Temperature -25°C to +55°C
Storage Temperature -40°C to +85°C
Mounting Standard DIN rail (35mm TS35/7.5 or 15mm).
Housing Material Self-extinguishing thermoplastic (Polyamide PA 6.6).
Protection Rating IP20 (front), IP40 (housed in appropriate enclosure).
Dimensions (W x H x D) Approx. 22.5 mm x 100 mm x 112 mm (1 Module width = 22.5mm).
Weight Approx. 0.15 kg.
Certifications CE, cULus, RoHS.
The ABB PSR25-600-81 is a compact, three-phase current monitoring relay from ABB's extensive PSR (Protection, Signaling, and Control) range. It is a specialized device designed for reliable monitoring and protection of three-phase systems against common faults such as phase loss (single-phasing), phase sequence reversal, and current asymmetry/unbalance.