1. This relay can monitor own working voltage (true RMS measurement). 2. 8 kinds of adjustable rated voltage. 3. Voltage measurement accuracy is not more than 1%. 4. Relay working status is indicated by LED indicators. 5. With super small volume, this relay can be mounted on 35mm DIN rail. Application: Equipment protection and control(tower crane, elevator, agriculture equipment, refrigerated trucks); Protect equipment from reverse running; Normal/emergency power supply switch; Protect against phase failure of a dynamic load. Function: Monitor L-L voltage (3-phase 3-wire system) Monitoring terminal: L1-L2-L3 Power: L1-L2 Rated working voltage: 220-230-240-380-400-415-440-460(P-P) Rated power frequency: 45Hz-65Hz Measuring range: 176V-552V Voltage threshold range: 2%-20% (rated voltage) Voltage fixed lag rate: 2% Voltage measurement error: less than equal 1% Power-on delay time: 0.5s Knob setting accuracy: 10% Reset time: 1s Temperature fluctuation error: 0.05%/°C, at=20°C Output: 1 x SPDT; 10A/ AC1; 250VAC/24VDC Minimum switching power: 500mW Overvoltage: 2%-20% Undervoltage: -20%-2% Action delay time: 0.1-10s adjustable Phase sequence protection: Yes Phase failure protection: Yes Power indicator: Green LED Output relay indication: Red LED Mechanical life: 1x107 Mounting : 35mm DIN rail mounting Mount altitude: less than equal 2000m Weight: . 78g/2.7oz size:95*18*64mm colour:white Material:plastic Package Contents: 1 * Voltage Monitoring Relay 1 * Instructions Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.