Time Mark Corporation B263 Three-Phase Power Monitor

The Time Mark B263 Three-Phase Power Monitor continuously supervises 208/240 VAC three-phase systems for phase loss, phase reversal, and undervoltage, de-energizing its output relay when faults are detected to protect motors and industrial equipment. Designed to monitor Wye or Delta configurations without a neutral connection, it is commonly installed in motor control centers, HVAC systems, pumps, compressors, conveyors, and other manufacturing equipment to help prevent unplanned downtime. Key specs include nominal 208/240 VAC (phase-to-phase), a voltage adjustment range of 160–240 VAC, 60 Hz operation, and a 1.5 W power draw; it uses SPDT output contacts rated 10 A at 240 VAC resistive, with a 50 ms response time and automatic reset, a repeat accuracy of ±0.1% of set point, and a dead band of approximately 2%. The unit features a surface-mount ABS plastic enclosure, operating temperature from -20°F to +131°F (-29°C to +55°C), and UL Recognized and CSA Certified listings. Common replacements include Time Mark B263M and B263SG.