Process control in resistance welding In electric resistance welding equipment, the welding current can be regulated by which of the following methods?

Introduction / Context:
Resistance welding relies on passing a large current through contacting workpieces to generate heat at the interface by I^2 * R. Accurate control of current magnitude and duration is essential for consistent nugget formation and weld quality.

Given Data / Assumptions:

• Power is delivered via a transformer to achieve low voltage and very high current at the electrodes.
• Multiple hardware methods exist to regulate the welding current.
• Pressure setting is important but does not itself regulate current magnitude.

Concept / Approach:
Current can be controlled by adjusting the input (e.g., phase angle control, voltage), by altering transformer turns on the primary (changing turns ratio), or by modifying secondary turns. All three approaches affect the output current. Modern machines may also use electronic controllers (thyristor/IGBT) for precise timing and waveform shaping, but the fundamental options listed remain valid.

Step-by-Step Solution:
Method 1: vary input supply (voltage/phase) to change transformer output.Method 2: change primary turns to alter the turns ratio, adjusting current capability.Method 3: change secondary turns (or tap selection) with similar effect.Hence, any of the listed electrical methods can regulate current.

Verification / Alternative check:
Machine datasheets show tap-changing on primary/secondary and electronic control of input as standard means of current regulation.

Why Other Options Are Wrong:
Choosing only one method ignores the others; “mechanical pressure only” impacts contact resistance and nugget shape but is not a direct electrical current regulation method.

Common Pitfalls:
Confusing current regulation with weld force control; both must be set appropriately but are distinct parameters.

Final Answer:
any one of the above