Finder 72.51.0.240.0000 Voltage Monitoring Relay, 240 V AC, 2 CO, DIN Rail

In industrial control panels, the Finder 72.51.0.240.0000 monitors single-phase AC voltage to protect equipment from over- and undervoltage conditions. It is a voltage monitoring relay with a nominal supply voltage of 240 V AC and a monitoring range of 180 to 280 V AC. The relay provides two changeover contacts rated at 8 A / 250 V AC, suitable for switching loads up to 2000 VA. Independent upper and lower thresholds, adjustable hysteresis from 5 to 20%, and separate start-up and trip delays allow precise control. Designed for 35 mm DIN rail mounting, it features screw terminals and LED indicators for supply, relay status, and fault. Operating temperature range is -20 to +60 °C, with housing protection IP40 and terminal protection IP20.

Key specifications

• Relay type: Voltage monitoring relay
• Number of phases: Single-phase
• Monitored voltage type: AC
• Nominal supply voltage: 240 V AC
• Monitoring voltage range: 180...280 V AC
• Output contacts: 2 CO (DPDT)
• Contact material: AgCdO
• Contact rating (AC1): 8 A / 250 V AC
• Max. breaking capacity (AC1): 2000 VA
• Adjustable thresholds: Upper and lower (independent)
• Hysteresis adjustment: 5...20%
• Start-up delay (tV): 0.5...10 s
• Trip delay (tD): 0.1...10 s
• Mounting type: 35 mm DIN rail
• Terminal type: Screw terminals
• Operating temperature range: -20...+60 °C
• Protection degree (housing): IP40
• Protection degree (terminals): IP20
• Indicators: LED (supply, relay status, fault)
• Width: 35 mm (2 modules)

Why choose it

This relay offers reliable voltage monitoring with independent threshold adjustments and wide delay ranges, making it versatile for protection and control tasks. Its compact 35 mm width saves space on the DIN rail, and the LED indicators provide clear status at a glance.

Ideal use cases

• Protecting motors and pumps from voltage fluctuations
• Monitoring supply voltage in control cabinets
• Triggering alarms or backup systems on voltage anomalies

Good to know

The relay is designed for AC voltage monitoring only. It does not include remote operation or integrated energy metering. The contact material is silver cadmium oxide (AgCdO) for durability.