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Resistance Welding SCR Contactors

Darrah Electric Company is “The Company” to call for resistance welding SCR Contactors. Darrah supplies contactors ranging in size from 5 KVA air cooled through 1500 KVA liquid cooled models. Darrah Electric Company maintains the largest inventories of resistance welding SCR Contactors in the country.

We provide:


Darrah offers solid state ignitron tube replacements. Our state of the art replacements are easy to install, more efficient, and less costly than ignitron tubes. Replacements are available in air and water cooled designs for A through Super E ignitron sizes.

Darrah stocks a full line of related accessories, such as R/C snubbers, thermostats, voltage suppressors, SCR thyristors, and IGBT’s. We offer technical support in selection, application, installation, testing, and repairing.

Resistance Welding Resource center



5000 Amp Heavy Duty
Darrah's 5000 Amp Heavy Duty Contactor ranks as the largest found in the resistance welding industry. Capable of welding current ratings of 8972 Amps at 10% duty cycle, the DPH7847-470 delivers 5144 Amps continuously. This Contactor is in Darrah's inventory with 2200 Volt rated SCR's. This is truly the choice for heavy seam and flash butt welder controls.
Air Cooled Ignitron Tubes
Darrah's replacement Air Cooled Ignitron Tubes are engineered so that no modifications are required to existing controls or timer. All wiring and assembly is complete and Darrah Ignitron Tube replacements are supplied with MOV and normally closed thermostat. Installation instructions are provided upon request.
Automotive Style
Darrah Automotive Hose Style SCR Contactors are the chosen favorite among high current/high voltage resistance welding users. These contactors are very popular in automotive welding applications. All contactors are rated for 100% continuous operation and are provided with 2600 Volt SCR's. This series is also popular for frequency converters, seam, and flash butt welding controls.
Contactor Replacements
Darrah offers a complete line of Solid State Air Cooled Mechanical Contactor Replacements for welding controls thru 60 KVA. Solid state replacements have no moving parts. No contacts to wear out. These are simple to install. Complete instructions are included.
Direct Water Cooled
Undoubtedly the most popular resistance welding contactors for the past thirty years are Darrah's Direct Water Cooled SCR Contactors. The selections shown are available in welding current ratings to 6526 Amps RMS at 50% duty cycle, 5144 Amps continuous. Choose between single or double sided cooled, and in SCR voltages to 4200 Volts. This product line is the workhorse in medium to heavy KVA welding controllers. Mounting bases and bus bar connections are similar throughout the series, therefore offering flexibility and conformity from 15 KVA through 1500 KVA designs.
HS-6 Design
Darrah HS 6 Design SCR Contactors have proven to be dependable for years in resistance welding controllers. Choose between two popular current ratings with SCR voltages to 1800 Volts. Darrah's HS-6 design switches are available with either 3/8 " or 1/2" water hose connections. As always, MOV's and R/C snubbers are easily added.
Indirect Water Cooled
Indirect water cooling refers to SCR Contactors that isolate the welding voltage from the water cooling. Darrah currently offers three types of indirect water cooled SCR Contactors. All three types have the same water cooled chill block, but offer different bus tang or power connections. Cooling blocks are available in aluminum or copper.
Isolated SCR Modules
Darrah offers Isolated SCR Modules featuring standard dual SCR modules witg integral water cooled bases. Our improved design has eliminated thermal barriers associated with separate cooling bases.
Water Cooled Ignitron Tubes
Darrah provides a complete line of Solid State SCR Ignitron Tube Replacements for Ignitron sizes A through Super E. Replacements are available in both water cooled and air cooled designs, and easily mount on existing Ignitron Tube brackets. Darrah�s single assembly replaces two tubes. Solid state replacements are more efficient and less costly than ignitron tubes, and contain no mercury. Darrah's replacements are engineered so that no modifications are required to existing controls or timer. Replacements are supplied with MOV, voltage suppressor and normally closed thermostat. Simple installation instructions are included. Thousands have been sold and installed.
Nihon SCR Contactors
Darrah offers a full line of drop and replacements of the Japanese style Nihon SCR Contactors. Installation instructions are provided upon request.