Electricity + Control March 2019

HAZARDOUS AREAS + SAFETY

HVI lightning protection: improved aesthetics

DEHN’s HVI lightning protection system is compact and neat, and is installed onto the top of the roof itself. Thinner and shorter than the old technology, the HVI is far less visible to the naked eye than a 30-metre free-standing mast, and therefore more visually pleasing. “For the client, namely the home-owner and architect, this means optimal adjustment to the architecture of the building and opens up new design possibilities. At the same time, however, the HVI system provides arguably even better protection from a lightning strike than a 30-metre mast.” Oelofse added that, given the technical expertise offered by the HVI technology, and the company’s confidence in its product, DEHN Africa is now prepared to offer insurance guarantees linked to its HVI system through the launch of DEHNinsure for thatched roofs, powered by HVI and providing a three-in-one offering of product and public liability, professional indemnity, and electronic equipment insurance. Enquiries: DEHN AFRICA:Tel: +27 (0)11 704 1487

DEHN Africa’s HVI technology has been available locally for some five years, but its suitability for game parks is only recently being re- alised in South Africa. Bakubung Villas is a brand-new development that is part of the world-renowned four-star Bakubung Lodge, one of the game lodges within the Pilanesberg National Park. The new units of Bakubung Villas are situated a short distance away from the existing lodge, and are available for private ownership. DEHN’s HVI technology was installed on all the new units of the villas. Joel Papenfuss, GM of Bakubung Lodge, said they had been particularly impressed by the aesthetic improvements offered by the HVI technology – which was highly suitable for the pristine bush surroundings – and by the maintenance requirements of the new technology when compared to the old free-standing masts. Hano Oelofse, managing director at DEHN Africa, said, “The old technology 30-metre free-standing masts for external lightning pro- tection are very visible, and from an environmental perspective, they do create something of an intrusion in the landscape. In contrast,

Ignition protection types for sensors in gas hazardous areas The use of sensors in hazardous areas can be realised through different, defined design concepts, referred to as ignition protection types. The most common ignition protection types for sensors for gas hazardous areas are outlined below.

Ignition protection type Flameproof enclosure ‘d’ IEC 60079-1 EN 60079-1 UL 60079-1

Protection principle

Use in zone

Constructive measures in/on the case prevent the propagation of an ex- plosion from inside the electrical instrument to the surrounding explosive atmosphere. Limitation of the energy (power, current, voltage) in the circuit of the electri- cal instrument, so that a spark or thermal effect cannot trigger any ignition of an explosive atmosphere.

Ex da = Zone 0, 1, 2 Ex db = Zone 1, 2 Ex dc = Zone 2

Intrinsic safety ‘i’ IEC 60079-11 EN 60079-11 UL 60079-11

Ex ia = Zone 0, 1, 2 Ex ib = Zone 1, 2 Ex ic = Zone 2

Non-sparking equipment ‘nA’ IEC 60079-15 EN 60079-15 UL 60079-15

In normal operation, under defined and described circumstances, the elec- trical instrument presents no ignition source.

Ex nA = Zone 2

Ignition protection types for use in zone 0, 1, 2 Ignition protection type Ex i ‘intrinsic safety’, is the most common ignition protection type for sensors. The circuits of these electrical instruments are designed, in terms of their energy (power, cur- rent, voltage), so that neither a spark nor the thermal development of the components used could cause ignition of the hazardous environment. The ignition protection type Ex d ‘flameproof enclosure’ allows the ignition of an explosion inside the electrical instrument. How- ever, the constructive design of the instrument prevents this ex- plosion from being able to escape from the instrument to ignite the surrounding explosive atmosphere. This protection is achieved by an appropriate thickness of the case wall, for example, as well as compliance with gap dimensions and additional specifications for installation. Ignition protection type for use in zone 2 While the ignition protection types already described can en- able the use of electrical instruments (sensors) in zones 0,

1 and 2, electrical instruments with ignition protection type Ex nA ‘non-sparking equipment’ are suitable only for use in zone 2. As the name implies, these instruments cannot cause a spark, nor do they contain any source of ignition from hot surfaces. However, this is only the case in normal operation, since in zone 2 an explo- sive atmosphere may exist only rarely and for a short time and a simultaneous failure of the instrument is unlikely. Selection of the ignition protection type While these are the most common ignition protection types for sensors, there are other too. The selection of the ignition protec- tion type for electrical instruments is determined by the specifi- cation of the operator and the ignition protection concept for a particular machine or plant. This can differ from region to region. For example, in Europe the use of ignition protection type Ex i is widespread, while in the USA, the ignition protection type Ex d, under the description ‘flameproof enclosure’, is often used. Enquiries:Wika Instruments.Tel. +27 (0)11 621 0000, or visit www.wika.co.za for more information.

Electricity + Control

MARCH 2019

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