Surge protection device

A surge protection device is a device intended to limit transient over-voltages, and to divert damaging surge currents away from sensitive equipment. 

Section 534 of the lET Regulations contains the requirements for the installation of surge protective devices (SPDs) to limit transient over-voltages where required by section 443 of BS 7671 2008 or where specified by the designer. 

R D. Martzloff and L. M. Levinson. In Surge Protective Devices in Electronic Ceramics—Properties, Devices, and Applications. (L. M. Levinson, Ed.)... 

Complete earthing system for intrinsic safety barrier and surge protection device. 

To avoid this, a clean supply is required for the computer network. This can be provided by taking the ring or radial circuits for the computer supplies from a point as close as possible to the intake position of the electrical supply to the building. A clean earth can also be taken from this point, which is usually one core of the cable and not the armour of an SWA cable, and distributed around the final wiring circuit. Alternatively, the computer supply can be cleaned by means of a filter such as that shown in Fig. 4.21 or by installing surge protection devices. 

Dry joints, open or short circuits Out-of-tolerance or incorrect components Missing or damaged conductive gaskets Loose/missing fixings in enclosures or cable shielding Pailure of a surge protection device Intermittent electrical connections... 

Step 1 of the lET s new Guide accepts that an EFS may need to maintain certain minimum levels of electromagnetic (EM) immunity despite at least one fault, such as the wear-out of a surge protection device by the surges it is exposed to over time. Another example is a broken filter ground connection, which could be caused by poor assembly shock, vibration, or corrosion over the lifecycle or wilful damage. 

It, however, requires a further improvement of the overall simulation method to achieve a quantitative agreement with a measured result. For example, a surge protecting device has to be carefully represented based on its circuit and the nonlinear characteristic. Also, a grounding impedance should be modeled considering its transient characteristic rather than a simple resistance adopted in this section. 

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