{"product_id":"time-mark-corporation-a257b-three-phase-monitor","title":"Time Mark Corporation A257B Three-Phase Monitor","description":"\u003ch3 data-section-id=\"17lc1ru\" data-start=\"0\" data-end=\"16\"\u003eDescription:\u003c\/h3\u003e\n\u003cp data-start=\"17\" data-end=\"663\"\u003eThe Time Mark Corporation A257B \u003ca href=\"https:\/\/plgautomation.com\/collections\/safety-components\"\u003e3-Phase Monitor\u003c\/a\u003e is designed to continuously monitor three-phase power systems for phase loss, phase reversal, and undervoltage conditions, helping protect motors and industrial equipment from electrical faults. 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 A257B for replacement, repair, retrofit, and preventive maintenance to improve equipment reliability and reduce unplanned downtime. \u003cspan class=\"\" data-state=\"closed\"\u003e\u003c\/span\u003e\u003c\/p\u003e\n\u003ch3 data-section-id=\"5ms9th\" data-start=\"665\" data-end=\"682\"\u003eApplications:\u003c\/h3\u003e\n\u003cp data-start=\"683\" data-end=\"1269\"\u003eThe Time Mark A257B 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, motor control panels, HVAC equipment, water and wastewater facilities, compressors, conveyors, and process machinery where reliable three-phase power monitoring helps prevent motor damage and production interruptions. \u003cspan class=\"\" data-state=\"closed\"\u003e\u003c\/span\u003e\u003c\/p\u003e\n\u003ch3 data-section-id=\"5hg6bl\" data-start=\"1271\" data-end=\"1300\"\u003eTechnical Specifications:\u003c\/h3\u003e\n\u003cp data-start=\"1301\" data-end=\"2276\"\u003e• Manufacturer: Time Mark Corporation\u003cbr data-start=\"1338\" data-end=\"1341\"\u003e• Manufacturer Part Number (MPN): A257B\u003cbr data-start=\"1380\" data-end=\"1383\"\u003e• Product Type: 3-Phase Power Monitor Relay\u003cbr data-start=\"1426\" data-end=\"1429\"\u003e• Series: 257 Series\u003cbr data-start=\"1449\" data-end=\"1452\"\u003e• Nominal Voltage: 480 VAC (Phase-to-Phase)\u003cbr data-start=\"1495\" data-end=\"1498\"\u003e• Voltage Adjustment Range: 380–480 VAC\u003cbr data-start=\"1537\" data-end=\"1540\"\u003e• Frequency: 60 Hz\u003cbr data-start=\"1558\" data-end=\"1561\"\u003e• Monitoring Functions: Phase Loss, Phase Reversal, Undervoltage Protection\u003cbr data-start=\"1636\" data-end=\"1639\" data-is-only-node=\"\"\u003e• Output Contacts: SPDT, 10 A at 240 VAC Resistive\u003cbr data-start=\"1689\" data-end=\"1692\"\u003e• Power Consumption: 3.7 W\u003cbr data-start=\"1718\" data-end=\"1721\"\u003e• Response Time: 50 ms Dropout\u003cbr data-start=\"1751\" data-end=\"1754\"\u003e• Repeat Accuracy: ±0.1% of Set Point\u003cbr data-start=\"1791\" data-end=\"1794\"\u003e• Dead Band: Approximately 2%\u003cbr data-start=\"1823\" data-end=\"1826\"\u003e• Reset: Automatic\u003cbr data-start=\"1844\" data-end=\"1847\"\u003e• Mounting: 8-Pin Socket\u003cbr data-start=\"1871\" data-end=\"1874\"\u003e• Indicators: TRIP and NORM LEDs\u003cbr data-start=\"1906\" data-end=\"1909\"\u003e• Wye\/Delta Compatible: Yes (No Neutral Required)\u003cbr data-start=\"1958\" data-end=\"1961\"\u003e• Operating Temperature: -20°F to +131°F (-29°C to +55°C)\u003cbr data-start=\"2018\" data-end=\"2021\"\u003e• Enclosure Material: ABS Plastic\u003cbr data-start=\"2054\" data-end=\"2057\"\u003e• Certifications: UL Recognized, CSA Certified\u003cbr data-start=\"2103\" data-end=\"2106\"\u003e• Application: Three-phase motor protection, industrial control systems, HVAC, pumps, compressors, conveyors, and process equipment. \u003cspan class=\"\" data-state=\"closed\"\u003e\u003c\/span\u003e\u003c\/p\u003e\n\u003ch3 data-section-id=\"1cz0398\" data-start=\"2278\" data-end=\"2302\"\u003eCommon Replacements:\u003c\/h3\u003e\n\u003cp data-start=\"2303\" data-end=\"2361\"\u003e• Time Mark A257BM\u003cbr data-start=\"2321\" data-end=\"2324\"\u003e• Time Mark A258B\u003cbr data-start=\"2341\" data-end=\"2344\"\u003e• Time Mark B257B\u003c\/p\u003e","brand":"time","offers":[{"title":"New","offer_id":51714028208430,"sku":null,"price":0.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0940\/0818\/1038\/files\/Ebay_website_image_4aca249e-0555-4cd1-85b6-253b9e3bd31f.jpg?v=1770414231","url":"https:\/\/plgautomation.com\/products\/time-mark-corporation-a257b-three-phase-monitor","provider":"PLG Automation ","version":"1.0","type":"link"}