Overview
The MDI 100NO-120A mercury contactor is a robust single-pole electromechanical switching device designed for high-current industrial control applications. With a 120V AC coil and proven mercury-displacement technology, this contactor delivers reliable performance in manufacturing, HVAC, pump control, and lighting circuits where precision switching and extended operational life are essential.
Key Features
- Single-Pole Normally Open (NO) — basic switching configuration suitable for single-phase loads and control circuits
- 100 Amp capacity at 240VAC, 80 Amp at 480VAC for resistive loads — wide voltage compatibility
- Hermetically sealed stainless steel tube — protects internal mercury and components from moisture, dust, and temperature extremes
- Fast switching response — 50ms operate time, 80ms release time for precise timing and load control
- UL-approved epoxy encapsulation — prevents voltage breakdown and ensures long-term reliability
- Extended operational life — rated for millions of switching cycles
Technical Specifications
- Coil Voltage: 120V AC, 50/60 Hz
- Coil Resistance: 380 Ω
- Coil Current: 137 mA
- Coil Power: 16.4 VA (7.1 W)
- Contact Rating (NO): 100A @ 240VAC; 80A @ 480VAC (resistive loads)
- Operate Time: 50 milliseconds
- Release Time: 80 milliseconds
- Operating Temperature Range: −35°C to +85°C (−31°F to +185°F)
- Dielectric Withstand: Up to 2,500VAC RMS
- Contact Configuration: Single-pole, single-throw (SPST)
- Mounting: Vertical position required
- Manufacturer: Mercury Displacement Industries (MDI)
- Series: 100 Amp Mercury Relay/Contactor Line
Typical Applications
- Industrial motor starters and pump control circuits
- Lighting circuit switching in manufacturing plants
- HVAC system control and compressor switching
- Oil and gas facility control systems
- General industrial electrical switching requiring high-current capacity and long cycle life
- Retrofit replacements for legacy mercury contactor installations
Compatibility & Replacements
Compatible With
- 120V AC control circuits (50/60 Hz)
- Resistive, inductive, and lighting loads up to rated amperage
- Industrial electrical panels and control enclosures
- Manual and automatic motor starter assemblies
- Standard terminal blocks and rail-mount fixtures supporting vertical orientation
Replaces / Drop-In Replacement For
- Durakool mercury relay/contactor equivalents (cross-reference available from MDI distributor)
- Other single-pole 100A mercury contactors with 120V AC coil and similar pin configurations
- Legacy electrical control systems requiring mercury contactor replacement
Works With
- Magnetic motor starters and IEC contactor assemblies
- Thermal overload relays and circuit protection devices
- Industrial PLC and hardwired control logic circuits
- Standard IEC and NEMA electrical enclosures
- 240V, 480V three-phase power distribution systems (within rated load limits)
