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What Is a Transient Voltage Surge Suppressor (TVSS)?

Transient Voltage Surge Suppressor (TVSS) is a device used to protect electronic equipment from transient overvoltage, spikes, or surges. With the increasing reliance on network infrastructure due to the proliferation of5G, IoT, and autonomous driving technology, the importance of TVSS is also continuously rising.

The main function of TVSS is to lower the voltage to a safe level and transfer excessive current to the ground, thus protecting electrical and electronic equipment.


How to Choose the Ideal TVSS Device

There are many factors that can cause spikes and surges, and choosing the correct TVSS device can help prevent equipment damage.

In the UL 1449 standard, the type ofTVSS is primarily determined by its installation location.

  • Type I TVSS devices are typically installed at the service entrance outside buildings, mainly to protect the main AC power entry. They provide the first line of defense during a surge, reducing the surge strength entering the building.

  • Type II TVSS devices are installed at branch panels inside the building, providing protection for the distribution panel. These devices typically further reduce surge voltage, ensuring stable voltage entering each branch circuit.

  • Type III TVSS devices are installed next to the protected equipment, offering branch and equipment-level protection. They serve as the last line of defense for precision electronic equipment, ensuring the equipment is unaffected by residual surges.

The Difference Between TVSS Devices and Surge Protectors

Although TVSS devices and SPDs (Surge Protection Devices) are both used to protect low-voltage electrical systems from transients, spikes, or surges, there are technical differences between them. TVSS is an industry term, whereas SPD was introduced and formally replaced the term TVSS in the third edition of the ANSI/UL 1449 standard. SPD is now categorized into various types, each suited for different applications and installation locations.

How Did TVSS Evolve into SPD?

Before the introduction of the third edition ANSI/UL 1449 standard, various terms were used to refer to devices that limit the impact of transient surge events, including surge arresters and TVSS. With the adoption of the new standard,Underwriter's Laboratories officially replaced the term "TVSS" with "Surge Protective Device (SPD).

TVSS devices can only be installed on the load side of the service entrance, whereas SPD devices can be installed on both the load side and the line side, providing broader protection.

How Do TVSS Devices Work?

To protect sensitive electronic equipment, TVSS devices are becoming increasingly common in residential, commercial, and industrial facilities. TVSS is a voltage-sensitive switch that continuously monitors the AC voltage input and output waveform. Under normal conditions, the device does not respond. However, when the voltage difference between the power source and the protected line is high enough, the switch will close, diverting the transient away from the electronic equipment to protect it.

In simple terms, the purpose of an SPD is to minimize equipment damage and downtime by limiting transient overvoltage before it reaches the protected equipment.

Transient Voltage Surge Suppressor (TVSS) is an important device for protecting electronic equipment from surge damage. With technological advancement and expanding application scenarios, bothTVSS and SPD play crucial roles in surge protection. To ensure the safety of your equipment, it is essential to choose high-quality TVSS devices.

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