Parafulmine refuge

Bergamo, 10/11/2024

The Case of the Parafulmine Refuge in the Province of Bergamo

The Parafulmine Refuge, located at 1,536 meters above sea level in the province of Bergamo, is a key destination for mountain enthusiasts. Restored in 1999 by the Comunità Montana Val Seriana, it offers a breathtaking view of the Orobie Alps and serves as a strategic stopover for hikers.

The name itself reveals a unique characteristic of the site: "Parafülmen," which means "Lightning Rod" in the local dialect. The area, with a lightning density of Ng=5.11, has a very high probability of being struck. Ng refers to the number of ground lightning strikes per year per square kilometer in a given area. Along with other parameters, it is one of the key factors required to draft a lightning protection risk assessment document for a structure. This document, often legally mandatory, determines whether a building needs a lightning protection system (LPS) and, if so, defines its specifications. The assessment is probabilistic, considering the structure’s characteristics, installations, incoming services, contained equipment, the terrain in which it is located, and, as mentioned, the Ng density. The higher the Ng, the greater the lightning risk.

The Initial Problem: Recurring Damage

Due to the high lightning activity in the area and the evident exposure of the structure to strikes, the refuge was initially equipped with an external and internal LPS (Lightning Protection System). However, in the early years of its operation, the refuge experienced numerous malfunctions and damage to electrical and electronic equipment caused by lightning. In 2015, the refuge’s managers sought the expertise of ZOTUP, recognized specialists in the field, to analyze and resolve the issue. The evaluation determined that the external LPS was adequate to protect the building structure and prevent dangerous step and touch voltages for people. However, the internal LPS was deemed inadequate, prompting a radical intervention to replace all installed surge protection devices (SPDs).

The Solution Proposed by ZOTUP

The refuge consists of two interconnected structures: the main refuge building and an external technical room. The electrical system operates off-grid and is powered by a photovoltaic system. Inside the technical room, a charge regulator supplies 24 V DC power to some of the refuge’s loads and battery storage. Additionally, two inverters (supported by a generator if needed) supply 230 V AC power via two short separate lines to provide alternating current to other loads in the refuge. Between late 2015 and early 2016, a complete overhaul of the internal LPS was carried out, replacing all existing SPDs with new ones designed to withstand both direct and indirect lightning discharges. Special attention was given to ensuring the necessary level of protection for the sensitive electrical and electronic equipment inside the refuge, which has limited impulse withstand capability against transient surges.

Technical Intervention: ZOTUP Surge Protection Devices

The following image illustrates the complete surge protection system installed at the Parafulmine Refuge. Each point (A-G) marks a key circuit position where ZOTUP surge protection devices have been installed.

To protect the 24 V DC regulator circuit in the technical room (figure 1, A), a ZOTUPLIMITER model L 7/30 DC 60 ff 2 (code 200 622) has been installed. This is a Type 2 surge protection device according to EN 61643-11 (2012-10) that provides three modes of protection. It has a discharge capacity of In 20 kA 8/20 µs, and the protection level Up is ≤ 220 V at 1 kA. A backup overcurrent limitation (pre-fuse) is not required since the line’s circuit breaker is ≤ 100 A and the short-circuit current is less than 1 kA. The device features a three-level status indicator with progressive residual performance indication, a distinguishing feature of ZOTUP SPDs. This characteristic is essential for optimizing preventive maintenance activities. The wiring was carried out using an insulated connector model CP1 (code 249 591) with triple V-pass connection. The same installation was performed on the 24 V DC line arriving at the refuge's electrical panel (figure 2, E).

To protect the inverters on the AC side, along the connection line to the refuge (figure 1, B and C), ZOTUPLIMITER model L 25/100 230 t ff 2 (code 215 120) SPDs were installed. These are 230V AC Type 1 and Type 2 surge protectors according to EN 61643-11 (2012-10). They provide three modes of protection, with an impulse discharge capacity of Iimp 25 kA 10/350 µs and In 60 kA 8/20 µs, and a protection level of Up ≤ 750 V at 1 kA. These SPDs also feature a three-level status indicator with progressive residual performance indication. The same model was selected for the inverter lines 1 and 2 arriving at the refuge's electrical panel (figure 2, F and G).

To protect the generator (figure 1, D), a ZOTUPLIMITER L 13/40 230 ff 2 (code 204 120) was selected. This is a bipolar Type 1 and Type 2 surge protector with three protection modes, pre-assembled for easy installation. It has a discharge capacity of Iimp 13 kA 10/350 µs and In 35 kA 8/20 µs, with a protection level of Up ≤ 790 V at 1 kA. As a signature feature of ZOTUP products, it also includes a three-level status indicator with progressive residual performance indication.

Results After the Intervention

Nearly ten years after the installation of ZOTUP SPDs, following the complete replacement of the previously installed ones, no further damage to the electrical and electronic equipment in the refuge has been recorded, despite the area being regularly struck by lightning. The case of the Parafulmine Refuge highlights the importance of relying on industry specialists capable of assessing risks, identifying, and providing the best solution. It also emphasizes the crucial role of installing products that can withstand the most severe atmospheric threats, ensuring reliable protection. Most importantly, it guarantees that even in a high-risk area, the structure and its equipment remain safe.

Why Choose ZOTUP

A leader in lightning and surge protection systems for over 30 years, ZOTUP S.r.l. offers a high-quality range of SPDs proudly Made in Italy. Constantly engaging with designers, panel builders, and installers, ZOTUP provides exceptionally high-performance and safe surge protection devices, backed by a highly qualified technical support team always available. Protected by five international patents and developed through 360 laboratory tests, ZOTUP SPDs offer a comprehensive range suitable for any circuit and application.

ZOTUP’s core values are simple yet essential: safety, quality, and innovation.

Three key features make ZOTUP surge protectors unique:

• The Fuse Function (ff), ensuring that in the event of an SPD reaching the end of its lifespan, it fails in an open-circuit mode without requiring additional series overcurrent limiters, such as fuses or inadequate circuit breakers;
• A progressive status indicator that visually displays SPD degradation through a color change (green-yellow-red), providing early maintenance alerts;
• Compliance with Pollution Degree 3, supporting voltages up to 500 V AC and an extended temperature range (-40°C to +80°C), allowing ZOTUP SPDs to be used even in harsh environments with conductive elements like humidity, condensation, dust, and salt, ensuring higher reliability.