Mercury Relays

MDRs or Mercury Displacement Relays are specifically designed for resistive loads typical in heating and process applications. Our mercury relays are available in 30 to 100 amp models with single, double and triple pole configurations. Coil voltages range from 24 to 600 Volts AC at 50/60 Hz and 48 to 250 Volts DC.


  • MDRs are superior to open contact electro-mechanical relays because they do not contain springs or button contacts which tend to wear, fuse together or burn out.
  • MDRs are capable of rapid on-off cycling in excess of 6 times per minute under resistive loads. This provides more precise process temperature control and eliminates the electrical noise that is caused by the on-off action of electro-mechanical relays and contactors.


Kelvin Technologies offers a wide range of configurations from stock and can immediately ship you the right MDR to meet your requirements.

SCR Relays

SCRs or Silicon Controlled Rectifiers are able to switch large levels of power and can be used in a wide variety of applications. SCRs even find uses in low power electronics where they are used in many different types of circuits ranging from light dimmers to power supplies to over voltage protection. The term SCR is often used synonymously with “thyristor” and is actually a trade name owned by General Electric.


  • SCRs are highly reliable and have very low maintenance costs
  • SCRs will give you precise control of your heating process that will result in extended heater life and improved product quality at much faster production speeds.


Kelvin Technologies can provide you with the correct SCR to fit your application.

SSR Relays

SSRs or Solid-State Relays are electronic switching devices that switch on or off when a small external voltage is applied across its control terminals. The relay may be designed to switch either AC or DC to the load and it serves the same function as an electromechanical relay, but has no moving parts.


  • SSRs are smaller and are more reactive than electromechanical relays
  • SSRs are not required to be de-rated as a result of contact erosion
  • SSRs do not generate electrical noise
  • SSRs are not sensitive to EMI (Electromagnetic Interference)
  • SSRs can typically switch currents up to 100 amperes
  • SSRs will last longer because there are no physical contacts to wear out
  • SSRs are inexpensive


Kelvin Technologies can provide you with the correct SSR to fit your application.