What equipment is typically used to maintain a stable arc in welding?

The equipment typically used to maintain a stable arc during welding is the welding machine or power source. This device provides the necessary electrical current and voltage that are crucial for creating and sustaining the arc between the electrode and the workpiece. The welding machine adjusts the output to ensure that the arc remains consistent, which is vital for achieving good penetration and a strong weld.

In the context of welding processes, the power source plays a significant role in controlling the welding parameters. Whether it’s a constant current or constant voltage machine, it is designed to maintain the right balance of energy to support the welding arc.

Other options, such as an arc stabilizer, while they might assist in specific situations, are not the primary equipment responsible for maintaining the arc. A protective helmet serves to shield the welder's face and eyes from harmful light and sparks but does not influence the arc stability. Hand tools are used for preparation and finishing tasks but also do not contribute to arc maintenance. Thus, the welding machine or power source is identified as the essential equipment for sustaining a stable arc during the welding process.