Time Mark Corporation 257B Three-Phase Power Monitor

Description:

The Time Mark Corporation 257B 3-Phase Power Monitor is designed to continuously monitor 208/240 VAC three-phase power systems for phase loss, phase reversal, and undervoltage conditions to protect motors and industrial equipment. Commonly installed in motor control centers, HVAC systems, pumps, compressors, conveyors, and manufacturing equipment where dependable three-phase power monitoring is essential. Maintenance teams, OEMs, and system integrators use the 257B for replacement, repair, retrofit, and preventive maintenance to minimize equipment damage and reduce unplanned downtime.

Applications:

The Time Mark Corporation 257B is a solid-state three-phase power monitor that continuously supervises incoming three-phase power and de-energizes its output relay whenever phase loss, phase reversal, or undervoltage conditions are detected. It is widely used in industrial automation systems, water and wastewater facilities, motor control panels, compressors, conveyors, HVAC equipment, and process machinery where reliable power monitoring helps prevent costly equipment failures and production interruptions.

Technical Specifications:

• Manufacturer: Time Mark Corporation
• Manufacturer Part Number (MPN): 257B
• Product Type: 3-Phase Power Monitor
• Nominal Voltage: 208/240 VAC (Phase-to-Phase)
• Voltage Adjustment Range: 160–240 VAC
• Frequency: 60 Hz
• Power Consumption: 2.4 W
• Phase Sensing: Phase Loss and Phase Reversal
• Voltage Protection: Undervoltage Monitoring
• Output Contacts: SPDT, 10 A at 240 VAC Resistive
• Response Time: 50 ms Dropout
• Reset Type: Automatic
• Mounting: 8-Pin Plug-In Socket
• Enclosure Material: ABS Plastic
• Operating Temperature: -20°F to +131°F (-29°C to +55°C)
• Certifications: UL Recognized, CSA Certified
• Application: Three-phase motor, compressor, pump, HVAC, and industrial equipment protection.

Common Replacements:

• Time Mark 257BM
• Time Mark 258B
• Time Mark A257B