A non-polar selenium surge suppressor is an electronic component used to protect electrical and electronic circuits from voltage spikes and transients. Selenium surge suppressors were once common, but they have largely been replaced by more modern technologies, such as metal oxide varistors (MOVs) and silicon-based surge protectors. Nonetheless, here’s an overview of what a non-polar selenium surge suppressor is and how it functions:
Non-Polar Selenium Surge Suppressor:
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Selenium Technology: Non-polar selenium surge suppressors are based on selenium rectifier technology. Selenium is a chemical element that can function as a semiconductor and has the property of changing its electrical resistance in response to changes in voltage or current.
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Non-Polar Design: “Non-polar” means that this type of surge suppressor is not sensitive to the direction of current flow. In other words, it does not have a specific positive or negative orientation.
How a Selenium Surge Suppressor Works:
Selenium surge suppressors are typically designed as a stack of selenium discs, and they operate as follows:
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Voltage Spike Detection: When a voltage spike or transient occurs in the electrical circuit, the selenium surge suppressor detects the increase in voltage.
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Change in Resistance: In response to the voltage spike, the resistance of the selenium stack changes. This change in resistance effectively diverts the excess voltage away from the protected circuit.
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Voltage Limiting: The surge suppressor limits the voltage across the circuit it is protecting, preventing it from rising to dangerous levels. This helps protect sensitive electronic components from damage.
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Recovery: After the transient event subsides, the selenium suppressor’s resistance returns to its normal state, ready to protect against the next transient.
Advantages:
- Selenium surge suppressors were once widely used and had several advantages, such as being rugged and capable of handling high-energy transients.
Disadvantages:
- One major drawback of selenium surge suppressors is that they are not self-healing. Once they divert a surge, they may degrade over time and become less effective at protecting against future surges.
- Selenium is a toxic material, and the disposal of selenium-based devices can be an environmental concern.
- These suppressors have largely been replaced by more modern technologies like MOVs and silicon avalanche diodes, which offer better performance, faster response times, and longer lifespans.
Due to the disadvantages and environmental concerns associated with selenium surge suppressors, they are no longer commonly used in modern electronics. Instead, you will find more advanced and reliable surge protection technologies in use today.