May June 2020 Electric.ie Magazine

14 ELECTRIC.IE • The Magazine & Website for the Irish Electrical Industry • Phoenix Contact The basics of surge protection M ore and more sensitive electronic equipment is being used every day in Ireland. Electronic devices get smaller and smaller and, while saving space is beneficial, sometimes it has its drawbacks. The smaller the electronics get, the more difficult it is to protect electronic devices against man-made surges and lightning-induced surges. The new Irish standard 10101-2020 reflect this change with a complete review on the sections affecting surge protection. What has changed for surge protection? Under the new rules, I.S. 10101- 2020, the following sections received a major overhaul: • Part 443 - Protection against transient over voltages of atmospheric origin or due to switching. This section details how you determine whether a surge protective device (SPD) is required for your installation with details of a risk assessment method. It is always a good idea to install an SPD and so you could negate the need to carry out your risk assessment by simply installing surge protection as a standard at the origin of the installation. • Part 534 – Devices for protection against over voltages. This section goes into detail about surge protection selection and erection and insulation coordination. It gives clear guidelines as to what type of surge protection is required in your installation and also, more importantly, how to install them correctly. • Part 712 – Photovoltaic systems. This section describes how to protect your PV system in both domestic and commercial applications. This includes protection on both the AC side and the DC side. How do we protect against Surges? Surge-protective devices (SPDs) can consist of: • Voltage-switching components: spark gaps, gas-discharge tubes (GDTs) • Voltage-limiting components: metal-oxide varistors (MOVs), suppressor diodes • Combinations of voltage- switching and voltage-limiting components The I.S. 10101-2020 stipulates to use different types of SPDs at certain installation locations. For the protection of power systems, three types/classes of SPDs (Class I / Type 1, Class II / Type 2, Class III / Type 3) are defined in IEC 62305-4 and IEC 61643-11. Type 1 [T1] / Class I SPDs Usually installed in facilities with external lightning protection system or facilities supplied by overhead lines. The typical installation location FIGURE 9.54: Multi-stage protection scheme in accordance to IEC lightning protection standards (see IEC 60364-5-53) for this kind of SPDs is the service entrance or the main distribution cabinet. An installation in close proximity to the main earthing busbar is recommended. Type 1 SPDs have a high discharge capacity (lightning current impulse Iimp [10/350 µs], surge-current impulse In [8/20 µs]). Typical surge- protective components used in Type 1 SPDs are spark gaps, big varistors and big GDTs. FIGURE 9.55: Pluggable Type 1 SPD with three L/N spark gaps and one N/PE spark gap; for the diversion of high-energy lighting currents (10/350 µs); four modes of protection; suitable for the protection of three-phase five- wire systems.