Transformers are indeed the most important components in power systems. But they are also quite vulnerable to voltage surges and transient overvoltage. These spikes, whether internally generated as a result of switching or externally caused by lightning strikes, damage transformer insulation, windings, and other connected equipment severely. This is where protective devices like surge protectors and lightning arresters come into play.
Surge protectors and lightning surge arresters are often confused as one device or used interchangeably, but they serve very different purposes.
What is a Surge Protector?
A surge protector is a device installed to protect electrical equipment, like a transformer, from unexpected voltage spikes. These spikes, also known as transient overvoltages, arise from internal switching events, utility grid fluctuation, or even indirect lightning strikes. These surges or transients may cause problems with the connected devices. When surge protectors detect excess voltage, they safely divert that current harmlessly to the ground.
What is a Lightning Arrester?
A lightning arrester is a device used to protect electrical installations from very high voltages, mostly due to direct lightning strikes or caused by a nearby lightning strike. Lightning arresters places are placed at high sites, like the high-voltage side of the transformer, so they can sense high voltages and can easily conduct that surge straight to earth.
Lightning Arrester vs Surge Protector: Key Differences
When it comes to protection against power overvoltage conditions within the electrical systems, lightning arresters and surge protectors serve the same purpose, but with very distinct end uses as far as their functions, designs, and applications are concerned. Within transformer systems, the fundamentals of such differences become crucial in ensuring complete protection against both lightning-induced surges and internal surges.
Purpose and Function
Lightning arresters are designed as a safeguard from the high-energy surges caused by direct or nearby lightning strikes. It acts as a bypass, where the leakage current from the lightning strike is channeled into the ground.
As far as Surge Protectors, they do protect equipment from low-to-medium voltage surges that can be caused by switching operations, fluctuation in load, or certain faults within the system.
Voltage Handling Capability
High voltage, like tens of thousands of kilovolts, can be withstood by lightning surge arresters.
On the other side, surge protection devices are built to protect from low-voltage surges, usually ranging from 120V to 600V.
Installation Site
Lightning arresters are installed on the entry point of the system- the high-voltage side of a transformer or substation- into which surges are prevented from entering the network.
Surge protectors are located downstream near the equipment they protect, such as control panels or data centers.
Response to Surges
Lightning arresters’ response time is extremely fast for high-magnitude impacts.
Surge protectors respond to these very frequent but low-energy transients, as the protection is continuous for low-voltage circuits.
Design and Components
A lightning arrester usually consists of a metal-oxide varistor or spark gap type, designed to ground even a high-energy lightning strike.
A surge protector consists of component types such as MOVs or gas discharge tubes, which clamp and absorb overvoltages.
Application in Transformers
Arresters are important when it comes to protecting transformer bushings and windings from lightning damage.
Surge protectors may also find uses within transformer control cabinets, relay panels, or systems associated with SCADA to protect low-voltage electronics.
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Why Both Are Important for Transformers
In substation transformer, there can be a crucial gap in protection if it relies entirely on one device. To ensure complete coverage, the use of both a surge protection device and a lightning arrester is needed.
Protection from Outside
Transformers are mainly outdoor or substation installations; exposure to direct lightning strikes or lightning surge-induced voltages can make transformers susceptible. A lightning arrester is meant to absorb or divert very high voltage transients from entering the coil windings of a transformer.
Without a properly rated arrester, one lightning event can create insulation failure or even loss of an entire transformer.
Shields from Internal Surges
The system can produce surges even without lightning, mostly due to the switching operations, energization of capacitors, or fault-clearing events. The sensitive control systems, relays, or smart monitoring equipment connected to the transformer may degrade due to such surges. This is where surge protectors play a key role. With panel-mounted surge protection devices and power surge strips, it clamps lower-energy overvoltages and prevents cumulative damage.
Layered Protection Strategy
When transformers use both types of protection, a layered defense mechanism gets activated:
Lightning surge arresters counter high-energy impulses at the entry for lightning surges.
Surge protection devices take care of residual surges that get away from the arrestor or originate within the system.
This double-protection concept is not just a good design, but often requires action to obtain dependable operation of transformers.
Long-Term Equipment Reliability
If one type of protection is ignored or neglected, the other might either cause slow but serious deterioration or might end up with instantaneous failure. The two devices used together will enable the transformer owner to lengthen service life, avoid maintenance, and mitigate costs from unplanned downtime.
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Conclusion
A lightning arrestor is intended to handle the high-voltage transient surges due to direct lightning strikes to protect transformers at the grid entry point. On the other hand, a surge protector, which is a panel-mounted or surge strip, is meant for internal or utility-generated lower voltage transient surge voltages.
Both combined guarantee an effective layered and dependable protection strategy against a wide range of electrical threats. Leaving any of it out would expose equipment to wear, service interruptions, or grave failure.
At Daelim Transformer, we are aware of the importance of lightning arresters and protection against surges. Our transformer solution incorporates built-in surge protection systems compliance with international standards, to assure long-term operational reliability.
Contact us today to see how Daelim Transformers helps build your power infrastructure to be safe and efficient.
