How to Protect Resistance Welding Transformers and MFDCs

August 23, 2016

A question to which this blog gives a summary answer to was asked of RoMan not too long ago!


What are the best means to protect resistance welding (RW) transformers and medium frequency direct current (MFDC) transformer rectifiers from failure due to over-temperature?

Summary Answer

Heat generation is the inherent function and benefit of the resistance welding (RW) process. The heat is generated by an electrical current, which is controlled and transmitted by electrical components. As a result, there will be a constant effect manifested by a rise in temperature that, without proper cooling, will affect the system’s electrical components. To avoid this scenario, proper electrical component sizing and proper water cooling are the best means of protection for RW transformers and MFDC transformer rectifiers from over-temperature—thereby ensuring safety, quality, and uptime. While there are many facets to RW machines, the answers to the “how to” question will focus on elements that are most closely related to protection from over-temperature.

There are several elements that play in the equation of protecting RW transformers and MFDC transformer rectifiers, including:

  • Electrical Component Sizing

    The electrical components that transfer energy to the weld include electrodes, adapters, busbar, cabling, transformer or MFDC, welding control, circuit breakers, fuses, and primary wiring. These electrical components require proper sizing.

  • Water Cooling

    To keep electrical components within rated temperature limits, it is important to properly size and cool electrical components to ensure operation within rated temperature limits. Water cooling is the most effective means to keep electrical components within rated temperature limits.

  • Water Cooling Specifications

    Common water cooling specifications include maximum inlet temperature in degrees (86°F or 30°C), pressure differential in pounds per square inch (lb/in.2) or bars, and especially flow rate, in gallons per minute (gal/min) or liters per minute (L/min).

  • Sensors

    A resistance welding production line, with any combination of manual and automated processes, relies on the proper application and feedback of sensors to ensure safety, quality, and uptime. Without sensors, any manual or automated process could be easily crippled.

  • Flow Switch

    The most effective solution to provide needed protection against serious damage from over-temperature is the rapid alert flow switch sensor. Best located in the “water out” circuit, the flow switch sensor offers the best protection against over-temperature of electrical circuit components due to sudden loss of cooling water.

To download a complete article including diagrams and tables on How to Protect Resistance Welding Transformers and MFDCs click the link below.

How to Protect Resistance Welding Transformers and MFDCs