Lightning Surge Protection
Protect Automation Electronics From Lightning Induced Voltages And Current
Lightning damage to variable frequency drives (VFD), programmable logic control (PLC) and Level Transmitter (LT) connected to AC power and communication circuits leads to production shut down and expensive repairs. Lightning surge protection has become a critical issue in recent years at the unmanned remote oil production and saltwater disposal facilities due to the increased amount of automation. While the cost of equipment replacement is of major concern, the cost of downtime exceeds all parameters. Loss of a single tank gauge can trigger shutdown of the whole production or saltwater disposal facility.
IEEE states couple of facts about cloud-ground strokes:
- Have been recorded reaching as far as 18.6 miles (30 km) horizontally from the base of the cloud.
- Peak discharge currents in each stroke vary from several thousand amperes to 200,000 A or more.
IEEE further states that people generally think of lightning damage as what happens at the point where a lightning terminates. The structural lightning protection generally protects from such events. But the lightning current pulse continues into conductive parts of the structure, cables, and even underground wiring and pipes.
Common Lightning Surge Damage:
- The most common damage arises from a lightning strike to the overhead power transmission lines. Lightning can also travel through the ground, reaching underground grounding rods, cables or pipes.
- The second most common damage results from strikes to or near the external wiring common to most remote facilities. Cable trays, equipment skids, submersible pumps, security systems, communication antennas and measurement instruments like tank level gauge can all be struck by lightning, and the lightning surges will then be carried into the control VFD, PLC and UPS panels via power and control cables.
- Lightning may strike nearby objects (fencing, flagpoles, signs) that are close to, but not directly connected to the facility. In this situation, the lightning strike radiates a strong electromagnetic field, which can be picked up by power & control wires, producing large voltages that can damage control circuit.
- A direct lightning strike to the structure is very rare, even in high-lightning areas but it does occur. It can severely damage a structure without a structural lightning protection system (LPS), and will generally damage most electronic equipment.
Petro Guardian offers an advanced lightning surge protection technique that addresses each of the possible sources of lightning surge damage:
- Type 1 lightning arrester for AC power entrance that have the capacity to handle high voltages and high currents induced by direct lightning on power transmission lines and those that travel through the ground.
- Type 2 lightning arresters for AC powered equipment panels that have the capacity to handle residual voltages and currents past Type 1 arrester but also have the capacity to filter the EMI and RFI radiations that may get induced due to near by lightning.
- Type 1 low voltage lightning arresters for signal wires entering control and measurement equipment where lightning currents get induced due to direct or indirect lightning and via lightning currents that travel across the ground.