In automated welding processes, the best method for monitoring the weld is remote monitoring using a Weld Camera. Not only is this method safer for operators; it enables better weld visibility than an operator can get by directly monitoring the weld using a weld helmet.
However, the harsh environmental conditions of industrial welding produce challenges for Weld Cameras. An obvious one is being able to withstand the extremely hot temperatures and contaminants of the welding environment.
And critical to the success of a Weld Camera is having High Dynamic Range imaging capability in order to provide clear images of both the super-bright weld arc and the surrounding metal background.
But image quality can still be compromised if the Weld Camera isn’t capable of dealing with the high levels of electromagnetic interference (EMI) that typically occur in automated industrial welding operations. This interference can be generated by welding equipment, electric motors, high-voltage power supplies, or specialized industrial equipment.
The Weld Imaging Problems Created by EMI
Field testing has shown that welding environments present many coupling mechanisms for electromagnetic noise. Noise can be coupled into electronic systems through conductive paths such as power-supply grounds. It can also penetrate into systems via electric or magnetic fields generated by the welding equipment or the work piece.
Electromagnetic fields generated by large current swings can also generate significant radio interference and transients. Arc welding equipment uses high-current power supplies to generate welding arcs. The sudden ignition of an arc or continuously pulsed operation of the welding creates high levels of electromagnetic and/or electrostatic noise due to the rapid change in voltage and current in a very short period of time.
It’s common to have currents in excess of 200A flowing through a work piece. In modulated welding, the current may change by 50A or more at up to 1kHz. Magnetic field coupling will occur when a circuit loop is driven by an alternating current, such as that generated by a modulated welding process. When that magnetic field passes through another loop, such as camera circuitry or interconnect cabling, it induces a voltage which manifests as noise.
Operating in High EMI Environments
Because of these difficulties posed by EMI, Xiris specifically engineered the XVC-O Weld Camera equipment to combat a broad spectrum of EMI.
- Multiple levels of power-supply filtering and transient suppression are used to protect the XVC-O computer system.
- A custom power distribution system, multi-layer noise filtering, and transient suppression is used in the XVC-O camera head.
- A robust SFTP (shielded foil screen twisted par) cable is used in conjunction with a proprietary differential analog video transmission system to maintain clean, noise-free video output even in the loudest of environments. The XVC-O camera cabling is also IP-rated for protections against water and contaminant ingress.
Conclusion
One of the many obstacles to getting high-quality weld images is overcoming the high level of EMI produced by industrial welding. When looking for a remote weld monitoring solution, make sure to take into account a Weld Camera’s ability to prevent EMI from distorting images.
