In multi-spot welding systems, equal weld currents are expected in the two weld circuits powered by one multi-spot transformer. For this reason, impedance balanced transformers are used and the designer of welding tools exercises great care to make the geometry of the two welding circuit identical. Regardless of these efforts, unbalances in weld currents of 10% and above exist due to uncontrollable differences between the welding circuits and deterioration of welding loop components causing unacceptable weld quality. The weld current equalizer balances the weld currents by transformer action. Other applications of the weld current equalizer are to balance the weld currents between two welding circuits operated by two single secondary transformers and to use the device as a weld current splitter to power two weld circuits from one welding transformer having a single secondary. Typical equalizer connections are shown on drawing R1959.

The advantages of the weld current equalizer are:

• Eliminates equalization of currents by trial and error
• Compensates for deterioration of welding loop componen
• Easy to install on new or existing machines
• No adjustments required
  
• No regular maintenance
• Rugged device

Rating
The curves on the rating graph represent the maximum unbalance of weld currents expressed in percent (%), which the weld current equalizers can balance as a function of the maximum secondary voltage available from the welding transformer. The process of determining the required rating is shown in the following examples.

Example 1

• Maximum Secondary Voltage 7.5 Volts
• Welding Current in Loop 1 15,500 A
• Welding Current in Loop 2 14,000 A
• Unbalance 15,500-14,000 = 1,500 A
• % Unbalance 1,500 / 14,000 X 100 = 10.7%*
• From Rating Curve: Use RWE 7/15
  

Example 2

• Maximum Secondary Voltage 11.5 Volts
• Welding Current in Loop 1 16,200 A
• Welding Current in Loop 2 18,400 A
• Unbalance 18,400-16,200 = 2,200 A
• % Unbalance 2,200 / 16,200 X 100 = 13.6%*
• From Rating Curve: Use RWE 12/15
  

*The percent unbalance must be based on the lower weld current representing 100%

Rating Graph

Selection Table