What is a TVSS unit?

Surge protector also known as Transient Voltage Surge Suppressor (TVSS), Surge Protection Devices (SPD) or Surge Suppression Equipment (SSE) is the equipment designed to protect electrical and electronic equipments from power surges and voltage spikes.

What is the unit of surge?

Surges are generally measured in microseconds. Every piece of electrical equipment is designed to operate at a specified nominal voltage such as 120 Vac, 240 Vac, 480 Vac, and so on.

What is Type 2 SPD?

The Type 2 SPD is the main protection system for all low voltage electrical installations. Installed in each electrical switchboard, it prevents the spread of overvoltages in the electrical installations and protects the loads. Type 2 SPD is characterized by an 8/20 µs current wave.

Is a TVSS a separately derived system?

(3) Separately Derived System. A TVSS can be connected anywhere on the premises wiring of the separately derived system, but not on the line side of the separately derived system overcurrent device.

How are TVSS rated?

Nominal Discharge Current (In) ratings of Type 1 TVSS can be 10 kA or 20 kA; whereas, Type 2 TVSS may have 3kA , 5 kA, 10 kA or 20 kA Nominal Discharge Current ratings.

What is the difference between TVSS and SPD?

There is no difference. The change in terminology from TVSS (transient voltage surge suppression) to SPD (surge protective device) was mandated by the 3rd Edition of the UL 1449 standard.

How does a Tvss work?

A TVSS or Transient Voltage Surge Suppressor protects sensitive electronics from short duration, extreme voltage spikes. This protection is accomplished by clamping the voltage to a safe level before the equipment is destroyed. The excess current is then diverted to the ground.

What is a surge load?

The surge impedance loading (SIL) of a line is the power load at which the net reactive power is zero. So, if your transmission line wants to “absorb” reactive power, the SIL is the amount of reactive power you would have to produce to balance it out to zero.

Do I need Type 1 or Type 2 SPD?

Type 1 SPD is characterized by a 10/350 µs current wave. The Type 2 SPD is the main protection system for all low voltage electrical installations. Installed in each electrical switchboard, it prevents the spread of overvoltage’s in the electrical installations and protects the loads.

Where is a TVSS installed?

load side
Within the USA “SPDs” are further categorized as:- the Transient Voltage Surge Suppresser (TVSS) and the Secondary Surge Arrester. In accordance with UL 1449 listing requirements, a TVSS device must be installed on the load side of the main over-current protection.

What is the minimum size of copper conductor used for surge protective devices?

Conductors. Conductors for SPDs must be at least 14 AWG copper or 12 AWG aluminum.

How many kA of surge protection do I need?

This protection in-depth strategy protects the facility and critical loads. In recommending a kA per phase rating a general rule of thumb – “the 3-2-1 rule of thumb” applies: The service entrance should be 300 kA, distribution panels 200 kA, and finally branch panels can be 100 kA per phase.