“St. Elmo’s Fire is a weather phenomenon in which luminous plasma is created by a coronal discharge from a sharp or pointed object in a strong electric field in the atmosphere (such as those generated by thunderstorms or created by a volcanic eruption).”
What scientists have come to know is that St. Elmo’s Fire is an electrical discharge that occurs because of ionization of gas (most of the time air) surrounding the conductor that is electrically charged, and can occur in high voltage systems. The corona ensues because the trapped air can’t be removed. Because of the ionization, corona discharge has a detrimental effect on equipment. Not only can it degrade equipment to the point of electrical breakdown, but it can also cause electrical interference.
Corona happens most frequently with coaxial types of cables. Because there are many individual strands inside the cable (conductor and shielding), there are many opportunities for air to become trapped and it is almost impossible to remove it. When the cables are mechanically assembled, it is difficult to eliminate the air between the high electrical potential conductor and the shield ground.
Connectronics’ Corona Line was designed to eradicate the corona effect by using over molded configurations to eliminate the air. A shield termination addresses electrical stress from strands captured between the inner and outer ferrule. A semiconductive layer over the center conductor allows the semiconductive layer and center conductor to be very close to the same potential thus nullifying the opportunity for the air to ionize. Corona free cables need to be used with a compatible termination process in order to create a reliable cable that is corona free. One crucial spot where air needs to be eliminated is at the interface between the plug and receptacle. This problem is removed by using a tapered interface to exclude air by allowing the mating halves to expel the air as they mate to one another; in theory creating a homogenous mass of dielectric insulation.
At Connectronics we service and work with industries such as aerospace, the Department of Defense, entertainment, medical, nuclear, underwater, and industrial. We offer high voltage connectors, high current connectors, underwater cables and connectors, specialized connectors, Wiremax high voltage lead wires, and more. To find the right connector and cable assembly for your job, contact Connectronics and talk to one of the professionals that make up our over 300 years of combined experience with connectors and interconnect experience.