{"product_id":"siemens-3ug3521-1al20-control-monitoring-relay","title":"Siemens 3UG3521-1AL20 Control Monitoring Relay","description":"\u003cdiv\u003e\u003cp\u003eSiemens 3UG3521-1AL20 Control Monitoring Relay is a compact, 22.5 mm wide digital monitoring relay from the SIRIUS 3UG4 family that protects electrical loads by watching current levels and signaling when they depart from a setpoint. It monitors current in the 2 to 500 mA range (AC\/DC) and switches a single changeover contact (SPDT) when the threshold is exceeded or undershot, with wiring via screw terminals for robust control-panel connections, and is designed for 230 V AC, 50\/60 Hz control circuits. The device supports adjustable response characteristics, including an ON delay and handling of transient spikes, with a typical delay window from 0.1 to 20 seconds and selectable hysteresis to define the trip band. While the 3UG3521-1AL20 has been superseded by newer models in the same family (notably the 3UG4621-1AW30), the core function remains: digital current monitoring to verify load operation and enable fault signaling, including open-circuit monitoring in automation applications. \u003c\/p\u003e\u003c\/div\u003e","brand":"Siemens","offers":[{"title":"Used Surplus - Excellent Condition","offer_id":46268183773418,"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-017.png?v=1788727429","url":"https:\/\/gtghardware.com\/products\/siemens-3ug3521-1al20-control-monitoring-relay","provider":"GTG Hardware","version":"1.0","type":"link"}