Ampere-squared-second recorder

A device is described which records the ampere-squared seconds in an electrical impulse of less than 0.5-second duration. A number of these have been used in resistance-welding applications to monitor the electrical variables and have contributed greatly to the uniformity of welds. The problem of indicating 1/60-second impulses at the rate of 100 a minute with the same device that will correctly integrate a half-second impulse has been solved by the use of a moving element with an infinitely long natural period, combined with a supplementary circuit which returns the element to the starting position in a fraction of a second.