Industrial applications include various types of equipment that need to be protected from the effects of surges. They are costly to the company owner: the price may be enormous and the failure, or even replacement, of those devices would incur major financial loss, possibly putting the very existence of the company at stake. The key aspects, from the perspective of trade unions, are the employees: they operate electrical equipment and, in the event of a surge, their lives might be at risk. The facts mentioned above, as well as other causes, represent substantial reasons why one should seek protection from surges. This function uses internal and external protection from lightning, such as the air terminals, grounding, protective busbar, surge suppressors, all jointly referred to as surge protection devices, SPD. There are a number of companies that produce a plethora of devices, yet not all of them are suitable for industrial applications.
The heart of it all, as the case typically is, lies in a directive or a legal requirement. In this specific situation, it is Czech Technical Standard ČSN EN 62305 Lightning Protection, Parts I through 4. The text also defines individual types of loss, risk, lightning protection systems as well as level of lightning protection. There are four levels of lightning protection (I through IV) which specify the parameters of lightning; the protection levels are the function of the risk level. In most industrial applications, the building is classified Level I or II. This corresponds to the peak values of lightning current Iimp (current impulse with parameters 10/350 µs) being as high as 200 kA. A qualified estimate suggests that 50 % of the overall Iimp current is arrested by the air terminals and delivered into the grounding system. The remaining 50 % becomes equally distributed among the inputs (i.e. among the external contacts entering the building), typically to the IT and communication cables, metal piping and LV power supply cables. Calculation of risk level as well as design of adequate arresting potential of the surge protection system are the functions of Hakelsoft, a software application, that is available as free download at our website www.hakelsoft.eu.
In the most adverse of situations, SPD need to arrest as much as 100 kA. When distributed into individual strands, the current values amount to 25 kA per strand (using a TN-C) system. That is why we recommend that master distributors of LV unit substations (in buildings qualifying as LPL I protection level) be fitted with the HS 50-50 sealed spark gap with gas filling. Being SPD Type 1, the equipment guarantees the equalisation of potential and disposal of the lightning current as well as the switching surge that is generated in the power supply lines entering the building.
It is capable of arresting Iimp currents as large as 50 kA. Unit substations of individual buildings then should be fitted with the SPC25, a combination of SPD Type 1 and 2, that features dual varistors for higher safety and offers 25 kA of arrestable impulse current. Secondary substations and control cabinets should be equipped with SPD Type 2. An example of that class in our product range is the PIII-275, which is offered as a complete, sealed unit or with replaceable modules.
If the protected device is located within 5 m from the secondary substation or control cabinet, the system must be further equipped with a SPD Type 3 unit, for example the PI-3k. It is a high-frequency filter with attenuation min. 30 dB in the frequency band 0.15‐30 MHz that also features protective devices – varistors produced for rated currents from 16 to 400 A. In that case, an impulse separation suppressor PI-L needs to be inserted between SPD Type 2 and 3 to provide correct coordination of the arresters. Shielded cables need to be provided between the substation and the protected equipment for its proper operation.
Whenever controlling electronics is being protected, it is recommended that SPD Type 3 be fitted directly within the device. The category of auxiliary SPD, which are fitted as the end-line devices in the electrical system (sockets) includes ZS-1.1 with optical signalling of correct function of the surge protection and ZS-1.2 which has a miniature piezosiren. Other type modules are ZS-1L and ZS-1P which are fitted in wall boxes below the socket, in floor boxes or gutters.
HAKEL also offers protection for situations where the roof of the building bears photovoltaic panels. Our recommendation is the PIVM PV V-series that mounts before the inverter and its interior is fitted with disconnectors which are deployed in the event of failure (overheating) of the varistors and with mechanical stop, that is inserted between the disconnected electrodes to prepare ideal conditions to kill a DC arc. Surge protection for alternating current is necessary, the best choice is the PIVM-12,5 V-series.
We recommend that arresters of this type be installed in rooms such as server halls, control rooms and offices. HT-TEL for protection of telecommunication equipment, HT-DATA for protection of transmission of data and information signals, HT-CCTV for protection of equipment that processes transmitted video signal, HT-NET 2/100 5cat are designed for computer networks prior to entering the network card and they are purpose designed for protection and data transmission in Generation 5 networks, and HAKELTEL 8.4 for installation in 19-inch distributors at the server for protection of data transmission in computer networks: the device offers RJ45 sockets as well as LSA-PLUS connectors. For protection of data and communication lines and for I&C instrumentation and controls for production lines, machinery and critical equipment, we recommend using DTB, DTE or DTNVE which deliver protection with lightning arresters and transient-voltage-suppression diodes. They are offered in various designs with selectable number of pairs and rated operating voltage in a given series. For communications with the RS 485 serial interface, we offer protection of those lines using SPD DTB 485 that protects the connected equipment against transverse and longitudinal surge. Protection of cameras and video signal aggregators, especially in electronic security systems and electronic fire protection systems EPS uses the H30 and H40 with non-linear components for currents Imax up to 6.5 kA. Protection of devices connected to the antenna system with coaxial cable should be fitted with KO-* surge protectors. Hakel offers a wide range of coaxial protectors for various types of connectors and specific performance classes that can be used in many types of applications. These SPD contain special lightning arresters with the maximum discharge current of Imax (8/20 µs) = 10 kA to provide reliable protection of reception and broadcasting systems against the effects of a lightning strike in close vicinity. They offer high attenuation of recoil no less than 20 dB.
The topic of protection against surges is not an easy one; the proper design depends on a number of contributing factors. We are inviting you to please contact our qualified sales representatives who will be happy to advise you in selecting the proper type of surge protection to provide protection of your property and minimise the loss and damage of your property.