Explosion protection (ATEX)

In environments with fine particles or flammable gas explosions can occur. To be allowed to apply electronics in such an environment these have to meet specific requirements regarding explosion protection. These requirements are formulated in the EU-directive 2014/34/EU, better known as ATEX-guideline 114. The precise requirements depend on the probability of the presence of, and nature of the fine particle or gas. Products that meet this guideline are provided with the Ex-logo.

There are a few ways to prevent the ignition of explosive atmospheres:

• The limitation of the maximum energy-content to a level so low that no spark can emerge, this is intrinsically safe. This means a limited value of the capacitive and inductive components in the product, of course also dependent on the supply voltage and current.
• The shielding of the environment. This can be achieved by encapsulating a product, or by placing the product in a very sturdy, gastight cabin, which is kept in overpressure. Additionally this casing needs to be able to withstand an explosion.

Applications

In principal, all environments where explosions could occur require Ex-proof products and measures to avoid ignition. Specifically the offshore, mining and chemical industry are important markets in this.

Expertise

Since the late 1990s, HedoN has developed ATEX-certified products for the offshore market and cooperates for that with partners domestically and abroad. The approach with a design for ATEX deviates significantly from the usual. A lot is involved to get comfortable in what the regulations entail exactly and how these should be implemented. From knowing how to determine if something can spark or ignite to how components can be made infallible according to the ATEX-definition. And eventually during production it needs to be checked whether indeed all requirements have been met. Experience therefore adds significant value in the development of ATEX-certified products.

Products

The most recent explosion-protected product that HedoN has developed is the measuring probe amplifier for Huisman Equipment, the MPA. A measuring probe is used to measure forces in a mechanical installation, for example in a crane. This happens by applying strain gauges to a hollow shaft. The output signal of this is in the order of magnitude of millivolts. To make this signal available multiple tens to a hundred meter farther along, an amplifier is needed. In terms of functionality, precision, EMC and certification by Lloyd’s this is a regular challenge. ATEX for such a product, on the other hand, does pose a significant challenge. The chosen way to ensure the explosion protection of this product is intrinsic safety. This meant that the cumulative systems capacity, including a maximum of 100 m wire, had to be restricted to approximately 600 nF. In addition, the voltage had to be restricted over a small number of large condensers with infallible components. Also view the productpage of the measuring probe amplifier via the link underneath.