Patent ID: 7928340

Claim:
A control method for an arc welding apparatus comprising a voltage detector, a voltage change amount detection part, a neck determination part and a neck prohibiting detection part, the method comprising: detecting a welding voltage using the voltage detector; calculating dv/dt using the voltage change amount detection part, wherein dv/dt is a change amount of the welding voltage per unit time; determining whether a neck of a droplet is formed by comparing the calculated dv/dt with a positive threshold value using the neck determination part; comparing the calculated dv/dt with a negative threshold value using the neck prohibiting detection part; and sending a first neck detection prohibiting signal from the neck detection prohibiting part to the neck determination part in response to a determination by the neck prohibiting detection part that the calculated dv/dt is less than the negative threshold value, wherein the first neck detection prohibiting signal prohibits the determining of whether a neck is formed for a first predetermined period of time beginning at the determination of the calculated dv/dt being less than the negative threshold value.