The need for industrial surge protection
Today’s industrial and professional equipment is dependent upon microprocessors and other sensitive electronic equipment, increasing the world’s need for greater protection from electrical surges. Embedded microprocessors, computers, programmable logic controls (PLCs) and other electronic circuitry that is used to automate industrial machine programming, tool changes, motor speed and other processes within sophisticated manufacturing systems is especially vulnerable. At industrial sites, power surges wreak havoc on equipment, causing catastrophic failures, interrupting processes and causing equipment to prematurely age, leading to failure. However by deploying industrial surge protection, manufacturers can mitigate potential problems and keep their equipment and the related processes up and running reliably without disruption or damage due to surge-related events.
In addition to externally generated surge events, such as lightning and grid switching, industrial equipment is also susceptible to damage by internally generated surges. The offending surges can be utility-generated overvoltage events, or power fluctuations created by machinery operating in adjacent areas of the plant. All will have the same adverse effect on both the machinery and shop productivity. Internally-generated surges reinforce the necessity for facility-wide surge protection applied at all stages of the electrical distribution system, from the electrical service entrance down to the single-phase loads.
Today only an industrial-grade surge protective device (SPD) like Raycap’s Strikesorb, is an acceptable solution. Raycap’s solutions can provide a stable electrical environment and virtually eliminate the losses caused by electrical overvoltage events. Its Rayvoss systems, featuring the patented Strikesorb technology, are trusted worldwide to protect sophisticated electrical equipment from damage caused by lightning surges, or large load switching occurring either in house or caused by industrial neighbors.
Lightning can damage by means of a direct strike to the equipment. This is a rare occurrence and can cause extensive equipment damage if not properly protected. Mitigation of direct lightning strikes on high voltage distribution lines and metallic structures is primarily accomplished by using grounded air terminals and shield air conductors above these structures. Use of these measures does not remove the risk of lightning damage down-line at critical equipment, but it does help reduce the severity of these strikes as they propagate throughout a facility.
Lightning can damage equipment by means of a strike to the power lines before they enter a building. Depending on the proximity of the strike to power lines and the quality of the grounding and lightning protection utilized on them, equipment damage can result from a lightning strike occurring several miles away. Surge protection in this case is located as close to the equipment as possible in order to provide optimal protection.
Lightning can damage equipment by coupling onto the supply lines. The coupling mechanism usually happens by direct strike to a structure. As the lightning surge moves down the structure it couples onto lines in parallel with it. Protection for this is usually accomplished by surge protection at the point where the lines join up with other lines. Examples of this are busbars, service panels and other distribution points. In some instances it is also desirable to protect critical equipment on those lines by installing surge protection at the equipment end.
Sources of risk from other voltage surges
Power surges are three phase AC events where the magnitude of the voltage increases significantly. They can result from problems with stability on the utility side of the substation or from heavy loads turning off on the load side of the utility. They can approach or exceed twice the line voltage in magnitude and last for only a few cycles to a couple of minutes. Protection from surges is usually accomplished by providing surge protection devices at the distribution centers and service panels. If average industrial surge protection devices are installed they will not handle long duration power surges. These surge protectors take themselves off line, but open internal thermal fuses or overcurrent protection devices and leave the sensitive equipment unprotected. Opening the breakers/fuses saves the surge protection, but leaves the equipment exposed to the remaining surge. Strikesorb-based SPDs are uniquely able to handle surge energy and shunt it to ground.
Power switching transients
Switching transients can couple in from the utility distribution lines, or can be generated on the plant side. They happen when highly inductive loads switch on and off. Switching transients can also be generated by electronic loads with damaged switch mode power supplies. Computer power supplies, electronic lighting ballasts and other office loads can cause lower levels of transient activity that can damage critical loads over time. Protection from the switching is usually accomplished by providing surge protection at the distribution points such as bus bars, distribution panels and at individual critical loads.
Surge protection strategy
T – Connection and in-line connections
Industrial surge devices can be wired in two different ways. The first is an in-line connection and the second is called either a T-connection or a parallel connection. The difference is that the in-line connection has a conductor to route the load current to a surge protective device, and then another conductor routes the current from the surge device to the load. With a T or parallel connection, a separate wire connects to the main load wire to the surge device. Thus with the T-connection, extra line length is placed between the surge protection and the wire it is protecting. Given the high rate of change (di/dt) of lightning currents, the additional line lengths can result in passing additional voltage, around 36V per centimeter of T-connection line length.