MDI Mercury Displacement 230NO-220AU Contactor

For industrial HVACR loads and heavy-duty motor control, the MDI 230NO-220AU Contactor remains a field-proven solution where reliability is non-negotiable. This 2-pole mercury displacement contactor is engineered for high-cycle applications, featuring normally open (NO) contacts rated for 30 Amps at 208/240VAC. Unlike standard definite purpose contactors, the liquid mercury contact interface ensures a low 0.003 ohms contact resistance and helps eliminate contact bounce and oxidation issues. The 220AU coil is optimized for 208/240V 50/60Hz circuits, drawing a modest 56 mA with 12.3 VA for efficient control. With a fast 50ms operating time and a robust 2,500 VAC RMS dielectric strength, this unit is built to withstand harsh environments ranging from -35° to +85°C. Whether you are replacing a worn relay in a pump station or upgrading a commercial heating system, this double pole contactor provides the vertical mounting stability and longevity professionals expect.

Key Benefits for Contractors

• Enhanced Durability: The mercury displacement design provides hermetically sealed contacts, preventing arcing and carbon buildup in demanding HVAC industrial applications.
• Rapid Response: Consistent switching speeds with a 50ms pull-in and 80ms release time ensure precise timing for motor and heater control.
• Optimized Thermal Performance: Rated for high-temperature environments up to 85°C, making it suitable for compact enclosures and equipment rooms.
• Reduced Maintenance: Self-renewing contacts eliminate the need for cleaning or filing, reducing long-term truck rolls.

Common Questions

Can the MDI 230NO-220AU be mounted in any orientation?
No, mercury displacement contactors must be mounted vertically (within 10 degrees of upright) to ensure the mercury pool makes proper contact and breaks correctly when the coil is de-energized.

What is the primary advantage of a mercury contactor over a mechanical DP contactor?
A mercury contactor is significantly quieter, has a much longer mechanical life due to the lack of moving contact parts, and can handle higher inrush currents without welding the contacts.

Is this contactor compatible with 208V and 240V systems?
Yes, the coil is rated for both 208V and 240V at 50/60 Hz, and the 30-amp contacts are fully rated for these standard industrial and commercial voltages.

Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.