MDI Mercury Displacement 35NO-120AT Contactor

Professional-grade MDI Mercury Displacement 35NO-120AT Contactor is designed for high-cycle industrial applications where mechanical relays fail. This single-pole normally open contactor features a 120V AC coil and is rated for 35 Amp resistive loads, making it the standard for electric heat control and industrial processing equipment. Unlike standard electromagnetic contactors, the MDI 35NO-120AT utilizes a hermetically sealed liquid mercury contact to provide a bounce-free switching environment, eliminating the arcing and pitting that leads to premature failure in traditional HVACR contactors. The 120VAC top-terminal design ensures clean wiring in tight control panels and remains quiet during operation, which is critical for noise-sensitive installations. Engineered for high-reliability power switching, this mercury relay can withstand millions of cycles under full load without contact erosion. Its stainless steel tube is encapsulated in high-grade epoxy to prevent voltage breakdown and handle high-temperature environments without the need for external heat sinks, ensuring consistent performance in demanding industrial heater or motor load applications.

Key Benefits:

• Extended Service Life: Hermetically sealed mercury-to-metal contacts prevent oxidation and withstand millions of cycles without degradation.
• Silent Operation: The liquid displacement mechanism eliminates the loud "clunk" and chatter associated with mechanical armatures.
• High Temperature Resilience: Capable of operating in extreme ambient temperatures without derating, unlike solid-state alternatives.
• Self-Renewing Contacts: The liquid mercury provides a fresh contact surface for every engagement, maintaining low and predictable resistance.
• Contamination Resistance: The sealed design protects the switching mechanism from dust, oil, and moisture in harsh mechanical rooms.

Common Questions:

Can I mount this contactor in any orientation?
No. Mercury displacement contactors must be mounted vertically (upright) to function correctly, as the internal plunger relies on gravity and mercury displacement to bridge the electrodes.

Is this contactor suitable for inductive motor loads?
While optimized for resistive heating loads (Argon-filled), this model can handle single-phase motor loads within its rated capacity. For heavy inductive cycling, verify the "H" suffix for hydrogen-filled variants if required by specific system specs.

Are there shipping restrictions for this part?
Yes. Due to the mercury content, this item cannot be shipped to certain states (including CT, MN, ME, NH, NY, RI, and VT) and requires specific hazardous material handling in compliance with local regulations.

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.