Time Mark Corporation A257B-480VAC 3Ph Power Monitor

Description:

The Time Mark Corporation A257B-480VAC 3-Phase Power Monitor is designed to continuously monitor 480 VAC three-phase power systems for phase loss, phase reversal, and undervoltage conditions to protect motors and industrial equipment from damaging power abnormalities. Commonly installed in motor control centers, HVAC systems, pumps, compressors, conveyors, and manufacturing machinery where dependable three-phase power monitoring is essential. Maintenance teams, OEMs, and system integrators use the A257B-480VAC for replacement, repair, retrofit, and preventive maintenance to improve system reliability and minimize unplanned downtime.

Applications:

The Time Mark A257B-480VAC is a solid-state three-phase monitoring relay that continuously supervises Wye or Delta power systems without requiring a neutral connection and automatically de-energizes its output relay whenever phase loss, phase reversal, or undervoltage conditions are detected. It is widely used in industrial automation systems, motor control panels, water and wastewater facilities, HVAC equipment, compressors, conveyors, and other process machinery where reliable three-phase voltage monitoring helps prevent motor damage, equipment failures, and costly production interruptions.

Technical Specifications:

• Manufacturer: Time Mark Corporation
• Manufacturer Part Number (MPN): A257B-480VAC
• Product Type: 3-Phase Power Monitor Relay
• Series: 257 Series
• Nominal Voltage: 480 VAC (Phase-to-Phase)
• Voltage Adjustment Range: 380–480 VAC
• Frequency: 60 Hz
• Monitoring Functions: Phase Loss, Phase Reversal, Undervoltage Detection
• Output Contacts: SPDT, 10 A at 240 VAC Resistive
• Power Consumption: 3.7 W
• Response Time: 50 ms Dropout
• Repeat Accuracy: ±0.1% of Set Point
• Dead Band: Approximately 2%
• Reset: Automatic
• Mounting: 8-Pin Socket
• Indicators: TRIP and NORM LEDs
• Wye/Delta Compatible: Yes (No Neutral Required)
• Operating Temperature: -20°F to +131°F (-29°C to +55°C)
• Enclosure Material: ABS Plastic
• Certifications: UL Recognized, CSA Certified
• Application: Three-phase motor protection, HVAC equipment, pumps, compressors, conveyors, and industrial control systems.

Common Replacements:

• Time Mark A257BM-480VAC
• Time Mark A258B-480VAC
• Time Mark B257B-480VAC