Relay Information & Restrictions

Due to mercury-added products being banned or phased out in some states, MDI cannot ship Mercury added products (Relays, Switches and Floats) to the following IMERC states:
Connecticut (CT), Minnesota (MN), Maine (ME), Massachusetts (MA), New Hampshire (NH), New York (NY), Rhode Island (RI), or Vermont (VT)

These states belong to the Interstate Mercury Education and Reduction Clearinghouse (IMERC) group, which have these restrictions.

Exemptions are currently being applied for in cases where Mercury Relays and Switches are being used to replace relays and switches in equipment originally manufactured with Mercury Relays and Switches. But, currently, MDI cannot ship into these states.

Mercury Relays (Mercury Contactors) are all designed and built to meet the most exacting demands of industry. They have won their high place in the electrical field by doing the tough and tricky jobs that ordinary equipment could at best do in an uncertain manner (especially resistive heating). They have proved their ability to stand up under the most adverse conditions of temperature, dust and moisture, in all types of applications. All the care required for the manufacture of high-grade instruments is used in the manufacture of the switches. All switch parts are specially cleaned, and contamination is avoided by use of tweezers, gloves, etc., when making assemblies.

Mercury Relays (Mercury Contactors) are hermetically sealed with high quality glass to metal seals.
The stainless steel tube is totally encapsulated in high grade UL approved epoxy to prevent moisture damage and voltage breakdown through the protective coating.
The coils are wound on compact nylon bobbins and molded onto the metal tube to provide minimum power loss. This allows for low coil power required to actuate the contactor. This also enables the units to handle high loads with minimum de-rating due to higher ambient temperatures.
Inert gases internally prevent excessive arcing between the mercury and the electrodes which enables the unit to function for millions of cycles with very low contact resistance, and minimum deterioration of the internal parts.
Available in all standard coil voltages, in single pole, two pole and three pole arrangements. Other coil voltages available upon request.
In multiple pole units each tube is actuated by its own coil. This eliminates pull-in variation between contact tubes, assuring consistent switching.

If you are wanting to return mercury relays, please refer to relay return policy and SDS here.

Example 235NO-120ATSHX-30
2 Pole, 35 AMP, NO (Normally Open Relay), 120A 120 VAC Coil, T (Top Contactor Terminals), S (Screw Terminals in place of Compression Terminals), H (Hydrogen Back-Fill gas for inductive loads), X (Hazardous Locations), -30 (-11 MOV on Coil, -17 DIN Rail Mounting & -18 Steel Strap)

1. Advantages Over Electromechanical and Solid State Relays
   1. Superior Performance and Reliability
      1. Long life
      2. Durable
   2. Compact Size
   3. Low, Predictable Contact Resistance
   4. Reduced RFI for Improved Interface Capability
   5. Handles a Variety of Loads
      1. Increases design flexibility
   6. Rapid On-Off Cycling Capability
      1. Mercury quickly dissipates contact heat
   7. Low Coil Power Requirements
   8. Minimal Derating Due to Higher Ambient Temperatures
   9. Quiet Action
2. Design and Construction
   1. Contacts are within a hermetically sealed steel body
      1. Impervious to adverse conditions
      2. No external arcing
   2. Arcing is in a gaseous atmosphere
      1. Quenches the arc
      2. Extends relay life
   3. Only one moving part (The plunger)
      1. No buttons to pit, weld or burn out
   4. One coil for each set of contacts
      1. Assures consistent switching
      2. Minimizes pull-in variation between contacts
   5. Epoxy encapsulated
      1. Moisture resistant
      2. High dielectric strength
      3. Permanently fixes contacts to coil; eliminating possible misalignment
      4. Helps dissipate heat and noise
      5. Rugged (impact resistant)
3. Benefits
   1. Reduction of Operational and Maintenance costs
   2. Increases Utilization and Productivity of Equipment
      1. By reducing down-time
   3. Installation and service is a routine operation
      1. Simple to install
      2. No sophisticated equipment is required
      3. Easy to trouble-shoot

• Typical Specifications
• On Normally Open Units
  • Operate Time 50 milliseconds
  • Release Time 80 milliseconds
• On Normally Closed Units
  • Operate Time 45 milliseconds
  • Release Time 60 milliseconds
• Contact Resistance .001 ohm *
• Dielectric Withstand 2500 Vac RMS
• Longevity Millions of Cycles
• Temperature Range -35 degrees C to 85 degrees C
• Coil Terminals #6 Binding Head Screws Torque to 7 IN-LB
• Load Terminals Pressure Connectors. Standard Accepts 1 to 8 AWG Torque to 45 IN-LB
• Ratings Derate over 480 VAC Res.
  • Exceeds 5000 VAC RMS across the contacts

* After Cycling Under Load

For UV Curing, and Various High Voltage applications. Available in Single Pole, Normally Open, and Normally Closed Units. The coils utilize 6-32 Wire Binding Screws, and the Contacts use Compression type terminals for 4 thru 14 AWG wire.

• Ratings
• 10 Amps @ 3,500 VAC
• 15 Amps @ 2,500 VAC
• AC Inductive Power Factor .7 or Greater
• Exceeds 5000 VAC RMS across the contacts

While MDIs contactors handle high inrush, such as lamp loads, very well, mercury contactors are susceptible to damage by short circuit currents, and should be fused to minimize short circuit fault currents. Fast acting UL class RK-1 and class J fuses and semiconductor I²t fuses more effectively protect relays than other fuses. These are low-peak fuses designed to limit short circuit currents. Regardless, when there is a short circuit, relay operations should be closely monitored afterward because of the possibility of concealed damage that could cause the relays to behave inconsistently.

• Mercury Displacement relays must mount vertically +/- 10 degrees.
• Control line can be protected with metal oxide varistor (MOV). Use suffix -11.
• Disconnect power before installing or servicing. Observe all electrical and safety codes and ordinances such as National Electrical Code (NEC) and the Occupational Safety and Health Act (OSHA).