Our Expert Offers Answers to Frequently Asked Questions About Power Quality

摘要

We have a number of resistance welding machines in our plant. I have heard that they can create power quality problems. What kind of problems can occur and how can I determine if I have them? A resistance welder will typically perform a series of welds in its cycle, each of which can draw several hundred amperes for a very short time. If insufficient attention was paid in the design of the distribution system, some significant problems can occur. First, one must consider the effect of voltage drop on the feeders supplying the welder. If the conductors have too much resistance for the peak current, the voltage will degrade momentarily during the weld such that other loads on the circuit may malfunction or 'drop out'. Second, the conductors feeding the welder must be of sufficient size to handle the heavy ampere duty cycle of the welder. If the feeder is too small, the cable and connections may overheat and fail.