DVRD-36, DVRD-48 DC voltage monitoring relay
Key Specifications & Features

• Voltage Ranges: Models are generally designated for specific DC voltages, such as DC 36V (DVRD-36) or DC 48V (DVRD-48).
• Adjustable Thresholds: You can set exactly when the relay trips using built-in knobs for overvoltage (U>) and undervoltage (U<) limits.
• Adjustable Delay: The action time (Tt) can be delayed so brief, harmless spikes don't trigger the system.
• Contact Capacity: Includes two sets of contacts (normally open/normally closed) rated for 6A at 250VAC or 30VDC.
• Power Source: It draws its operating power directly from the measured circuit, meaning no extra power supply is needed.
• Installation: Compact, modular units designed to snap onto a standard 35mm DIN rail (guide rail).

How They Work (The 1-2-3)

1. Real-Time Vigilance: The relay constantly watches the DC line. Think of it like a smart guard dog that only barks if the voltage goes out of bounds.
2. The Trip Phase: If the DC line drops below your safe undervoltage limit or spikes above your overvoltage limit, the relay counts down its delay time. 
3. The Disconnect: Once the countdown ends, the relay switches its internal contacts, safely cutting off power to prevent damage to your equipment. A visual indicator turns on to let you know a fault happened