Created by: Glen Zhu | Updated Date: Mar 13, 2023
Transients and surges are the same phenomena in the surge industry. These could be voltage, current, or both. They typically have a waveform with a very rapid ascent to the peak and a significantly slower falloff speed. See the spike shown in the below diagram:
Transients are known to damage sensitive electronic equipment in homes, schools, commercial, industrial, and factories, etc. The damage caused to electronic loads costs billions of dollars a year.
The key features of a surge protective device are its capacity to reduce voltage to the lowest possible level and to divert excessive current values to the ground.
Prior to the third edition of the ANSI/UL 1449 standard being introduced, there were various terms used when referencing devices intended to limit the effects of transient surge events like the terms Surge Arrester, and TVSS.
TVSS is the industry term for “Transient Voltage Surge Suppressor”.
With the adoption of ANSI/UL 1449 – Third Edition, the term “TVSS” has been officially replaced by Underwriter’s Laboratories with the term “Surge Protective Device (SPD)”.
At the technical level, TVSS and SPD are absolutely NOT interchangeable.
TVSS (Transient Voltage Surge Suppression) has always belonged to a larger family of surge protective devices (SPD).
SPDs are now classified as Type 1, Type 2, Type 3, or Type 4 and are selected based on application and the location where they are to be used.
For those applications similar to where a surge arrester would have been used on the line side of the system, it would now require a Type 1 SPD. In those applications where you once placed TVSS surge protectors on the load side of the system, these same installations require a minimum of a Type 2 SPD.
That’s to say, a formerly known TVSS surge suppressor is now a type 2 SPD as in the old version of the UL standard.
TVSS could be installed at the load side of the service entrance only. Yet SPD can be installed either at the load or line sides.
For protecting sensitive electronic equipment, the Transient Voltage Surge Suppressor (TVSS) is becoming more common in residential, commercial, and industrial facilities.
Since a TVSS is a voltage-sensitive switch, it constantly monitors the AC voltage input and output waveforms. Nothing happens under normal conditions.
When the voltage difference between the power source and the protected line gets high enough, the switch closes and diverts the transient away from the electronic equipment, ultimately protecting sensitive electronic equipment. A TVSS surge protector contains at least one nonlinear component.
Simply said, the purpose of SPDs is to minimize equipment damage and downtime by limiting transient over-voltages before they reach the devices they are designed to safeguard.
There are numerous factors that might lead to spikes and surges, and proper selection of TVSS can assist guard against equipment damage.
In UL 1449 standard, the type of a TVSS is mainly determined by its installation location.
The type I TVSS is designed to protect commercial and industrial facilities from the damaging effects of lightning.
Power cables carry the damaging current into facilities. The device shunts these damaging currents safely to earth ground.
It is also applicable anywhere within the power distribution system.
After many years of using the term “SPD (Surge Protective Device)” by UL, no standards group uses the term “TVSS” anymore. It is now more commonly used in UL-standard nations including the United States, Canada, and several nations in Central and South America.
LSP team offers a full range of TVSS Surge Suppressors designed to protect sensitive equipment, minimize preventative maintenance, and prevent unscheduled equipment downtime.
LSP’s reliable surge protection devices (SPDs) are designed to meet the protection needs of installations against lightning and surges. Contact our Experts!