The Propagation of Surge Protective Devices
The Propagation of Surge Protective Devices
Do you have a computer sitting on your desk? If so, chances are you have a surge protective device under your desk. As the use of products vulnerable to transient voltage surges and spikes continues to increase, the propagation of surge protection devices continues to increase. This article will focus on several types of surge protective devices, what they are, how they are tested, and the importance of markings, instructions and proper usage of the devices.
With the expanding surge protective devices industry comes a learning curve for code authorities, for electricians, for consumers and for the safety testing agencies. The code authorities begin to see an influx of different types of surge protective devices in the field and need to determine the proper usage and installation. Electricians need to know how to correctly install permanently connected surge protective devices. Consumers have to educate themselves as to which surge protective devices to purchase to meet their surge needs as well as how to install and use them safely. The safety testing agencies have to expand their knowledge base of surge protective devices to keep pace with the state of the art designs.
What is a surge protective device and what does it do? A surge protection device is a device composed of any combination of linear or non-linear circuit elements intended for limiting surge voltages on equipment by diverting or limiting surge current. A surge protective device prevents continued flow of follow (power) current and is capable of repeating these functions.
Surge protective devices are available in many varieties, one of which is the transient voltage surge suppressor commonly referred to as TVSS. A TVSS may be permanently installed or may be of the cord-connected or direct plug-in style. Each type of TVSS is intended for use on the load side of the main service disconnect in circuits not exceeding 600 volts rms. The main service disconnect is considered to be the first overcurrent protective device between the distribution transformer secondary and the service entrance.
The basic safety standard used to test TVSS is UL 1449, the Standard for Safety for Transient Voltage Surge Suppressors. UL 1449 addresses construction items such as enclosure requirements, minimum wiring size for internal wiring as well as field wiring, acceptable spacings between circuits of opposite polarity or to metal walls of an enclosure, proper grounding means, and suitability of mounting to name a few. UL 1449 also contains testing, marking and installation instruction requirements.
As well as containing the basic safety tests known to many UL electrical safety standards such as Leakage Current, Normal Temperature, Dielectric Voltage Withstand, etc., UL 1449 also contains a Measured Limiting Voltage Test. The measured limiting voltage is the maximum magnitude of voltage, measured at the output (leads, terminals, or receptacle contacts) of the TVSS during application of a test impulse of specified waveshape and amplitude. The Measured Limiting Voltage Test includes a duty cycle to determine that the surge suppression components can repeatedly limit the transient voltage surge test waveform without degradation.http://watchfuleyesolutions.com/








surge protective devices
surge protective devices