{"product_id":"schweitzer-engineering-laboratories-sel-321-phase-and-ground-distance-relay","title":"Schweitzer Engineering Laboratories SEL-321 Phase and Ground Distance Relay","description":"\u003cdiv\u003e\u003cp\u003eThe SEL-321 Phase and Ground Distance Relay from Schweitzer Engineering Laboratories is a protective relay that provides impedance-based phase and ground distance protection for electrical power lines and feeders. Identified on the unit by part number 321326256HNB536, this relay is part of the SEL-321 family, with documented variants SEL-321-0 and SEL-321-1 displayed on the official product page. Core functions announced in official data sheets include Phase Distance Elements and Ground Distance Elements (Mho distance), enabling accurate measurement of phase- and ground-fault distances to determine when to trip. By combining distance protection with overcurrent logic, the SEL-321 supports protection schemes that respond to faults along a line segment while minimizing unwanted trips. Common applications include transmission-line protection and feeder protection in utility substations and industrial systems, where impedance-based reach settings help tailor protection zones to system topology. The device is designed to integrate into standard protective relay schemes and is built to the SEL portfolio's emphasis on reliability and precise protection calculations. Its documented capability to monitor both phase and ground faults via distance elements makes it a suitable choice for projects requiring coordinated, fast fault isolation on medium- to long-length lines.\u003c\/p\u003e\u003c\/div\u003e","brand":"SEL","offers":[{"title":"New","offer_id":46283481514218,"sku":null,"price":0.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0716\/8039\/3450\/files\/GTG-STOCK-020.png?v=1788727428","url":"https:\/\/gtghardware.com\/products\/schweitzer-engineering-laboratories-sel-321-phase-and-ground-distance-relay","provider":"GTG Hardware","version":"1.0","type":"link"}