Customer application
Safe Underground

Electricity is one possible ignition source that carries enormous risk in underground coal mining: Even a small spark can ignite an explosion. Manufacturers of machines for underground use must therefore ensure that there are no ignition risks in their systems. That is why Hazemag & EPR relies on controllers and other products from WAGO.

Since the introduction of the European Directives, manufacturers of products intended for the European economic market have been required to provide them with the CE marking and a corresponding declaration of compliance. This legal requirement is found in Article 114 of the current valid European Treaty. For machines, that primarily means that they have to satisfy Machinery Directive – 2006/42/EC. If they are to be used underground in hazardous areas, such as in coal mining, then they must additionally satisfy the ATEX Directive 2014/34/EU. This serves to prevent any mine gas that may be present, like methane, from being ignited through the use of this equipment. The manufacturers must ensure that their equipment has no ignition risks.

Advantages of the intrinsically safe version of the WAGO-I/O-SYSTEM 750:

Fieldbus-independent, flexible and robust
Carries all internationally relevant approvals
Compact design favors use in tight spaces

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The Story

Familiar Standards – Even in Hazardous Areas

That’s why Hazemag & ERP, whose machines are used for underground tunneling, equips its electrical switching devices with intrinsically safe automation components from WAGO. These components allow automated control of the machine’s electrical systems, even in hazardous areas, while satisfying the usual standards. Without safety measures like this, underground mining would be impossible, because methane is constantly being released. If the concentration of the released gas passes the so-called lower explosion limit (LEL), then it becomes an explosion hazard. If an ignition source is present, then a LEL of five percent can cause a firedamp explosion. According to safety policies, at a concentration of only one percent, methane in the air, any monitored electrical equipment must be deenergized. Specifically, the electronics in these machines must be designed and implemented in an explosion-proof version according to the relevant standards.

Strict Requirements on Machines

HAZEMAG & ERP GmbH, located in Dülmen in Westphalia, also has to address this challenge. Mining is an important area for this equipment manufacturer, in addition to the cement, gravel and recycling sectors. At its headquarters in Dülmen, it develops, designs, manufactures and sells multifunctional machines for underground tunneling, among other things; its subsidiary HAZEMAG Control Systems (HCS) builds the necessary electrical switchgear units in Essen. “When we deliver machinery for mining, not only does it need to work for years without any failures – it also has to be Ex protected,” says Armin Kaufmann, Head of Sales at HCS, explaining the challenges.

Safety on the Go

In order to comply with these special regulations, the electrical components of the systems must meet with the valid standards and regulations, explains the expert. Automation components from WAGO fit the bill, as they comply with the “intrinsically safe” type of protection as per EN 60079-11. “This allows us to guarantee that no ignition of potentially present explosive atmospheres can occur due to the control circuits in the machine.”

Simple, Dependable Transmission

HAZEMAG Control Systems has international approvals, like UL 508A, NFPA79, and CAN/CSA C22.2 No.14, which allow the company to offer their mining technology on the international market. This company from Essen also uses function modules from the intrinsically safe variant of the WAGO-I/O-SYSTEM 750 to collect signals from actuators, sensors and valves from Zone 0/20 and 1/21 hazardous areas and to transmit the data in a simple and safe way to the higher level machine control, for which the Ex-variant is also used. “The system suits our needs perfectly. The Ex i modules form an intrinsically safe segment, which offers all of the advantages of modern fieldbus technology when integrated into a standard node. These include fieldbus independence, a high degree of flexibility and durability. In addition, they also have all of the international approvals that are relevant to our work,” says Kaufmann.

Use in Compact Spaces

This expert has another important argument in favor of WAGO: The small installation size of the WAGO-I/O-SYSTEM 750, which allows use in very tight spaces – up to sixteen channels can be accommodated in modules that are only twelve millimeters wide. “Size is always an issue, particularly underground. Control cabinets have to be particularly compact because the available space is limited. WAGO allows us to save space in our control cabinets,” says Kaufmann.

Into the Future with WAGO

Recently, mining has been in a difficult position all around the world: The breakthrough in renewable energies in China, the crisis in Ukraine and the Russian embargo all add up to circumstances that cause economic headaches for producers and exporters of mining equipment. However, Kaufmann views the future optimistically, since in his view, the order situation in this sector is already starting to relax. In the near future, HAZEMAG will supply tunneling machines to Kazakhstan, Russia and Turkey – with WAGO on board.

Text: Kay Miller | WAGO

Photo: HAZEMAG

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Customer application Safe Underground