Question

what uses a low open circuit voltage to start the arc?

low frequency
lift arc
high frequency
scratch start

Explanation:

Analyze the question requirements

The question asks which arc starting method uses a low open circuit voltage (OCV) to initiate the welding arc.

Evaluate the starting methods

Using the Open Circuit Voltage and Plasma Arc Starting Methods knowledge points:

• High frequency (HF) starting uses high-voltage, high-frequency electricity to jump the gap between the electrode and the workpiece without touching.
• Scratch start involves rubbing the electrode on the metal, which can cause contamination and requires standard open circuit voltage.
• Lift arc starting is a technique where the electrode touches the work with a very low voltage and current limit (low OCV) to prevent sticking and contamination. Once lifted, the machine detects the break in contact and increases the current to establish the full welding arc.

Identify the correct option

The method specifically designed to use a low open circuit voltage to start the arc safely without tungsten contamination is the Lift arc method.

Answer:

• Low frequency
• Lift arc (Correct answer)
• High frequency
• Scratch start