A term describing the shape of the static volt-ampere curve of a constant potential welding machine. Slope is caused by impedance and is usually introduced by adding substantial amounts of inductive reaction to the welding power circuit. The amount of slope can be controlled by a variable reactor in the a-c portion of the welding. It should be remembered that a reactor inherently opposes change in the welding current.

As more reactance is added to a welding circuit, there is a steeper slope to the volt-ampere curve. The addition of reactance does two things: (1) it limits the available short circuit current and (2) it slows the rate of response of the welding machine to changing arc conditions. These factors assist in decreasing the current surge when the electrode makes short-circuiting contact with the base metal. The result is decreased spatter from the welding arc.

It makes no difference whether the reactor is in the primary or secondary a-c circuit, since there will be no significant change in the performance characteristics either way. Resistance may be added to either the a-c or d-c circuit to accomplish the same purpose, but it is a more expensive method. Resistance will introduce more slope with less slow-down of response time. See CONSTANT VOLTAGE POWER SOURCE

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