Controls & Transformers
Questions and Answers
As in all electrical devices the circuit breaker is part of the safety system. It insures that if there is a short downstream of the breaker or a sudden spike in amperage, it will trip and prevent further damage to any equipment or wiring downstream. Sometimes facilities use fusible disconnects to perform this same function.
Weld controllers can be designed to provide several types of secondary currents. Until recently AC alternating current controllers were the dominant product. With the advent of robots and the need for smaller/lighter transformers mid frequency welding has become very popular. It has also replaced many applications for DC direct current welding. Capacitive discharge CD welding continues to have some applications.
Upslope is a term to describe the beginning a weld cycle when the current is gradually increased from some lower value to a higher value over a period of time usually 3-10 cycles in standard AC welding. At the end of the upslope period then normally the full desired current is applied for the desired length of time.
Due to the high currents that are present in a control cabinet it is necessary to isolate any connections to the cabinet that can create a potential path to ground. Water is one of these. Therefore special attention to the connectors through the cabinet must be made to insure the fittings are electrically isolated.
These fittings insure that the water system will remain electrically neutral.
Reference: RWMA - Resistance Welding Manual 4th Edition
AWS Standard: J1.2 Guide to Installatio and Maintenance of Resistance Welding Machines
Many controls are capable of monitoring and storing the actual weld parameter data generated during a weld. We are talking about the actual weld current, voltage, displacement and any other parameters. This data is maintained for a finite period of time in the control. At the end of this time it is erased or can be downloaded for storage.
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