IT security for critical infrastructure

Heating the living room to a comfortable temperature in just a few minutes – in many households this can be done in no time at all, and in almost every second household using natural gas. However, end consumers generally pay little attention to the complex path that the energy source takes between the extraction site and its destination. Security of supply is also rarely a cause for concern. This is because electricity, water and gas are regarded as constants in Germany, and disruptions to supply are the exception.   

This is due, among other things, to regional distribution network operators such as e-netz Südhessen AG, which operates electricity and natural gas networks for electricity and gas suppliers. As high system availability is a top priority for e-netz Südhessen, the Darmstadt-based company itself monitors the condition of control cabinets in decentralized facilities such as transfer stations and biogas plants where TURCK's IM12-CCM control cabinet monitors — CCM stands for Cabinet Condition Monitoring – detect when a door is opened or when temperatures are too high.  

Strictly controlled gas pressure regulation  

In the e-netz Südhessen network area, ten transfer stations enable natural gas to be fed into local networks at the appropriate pressure. e-netz Südhessen takes the gas at a pressure of 30 to 80 bar and reduces it to supply pressures between 12 and 13 bar. This process, also known as "decompression," generates cold. It is therefore necessary not only to filter the gas, add odorants and reduce the pressure, but also to preheat it. This is followed by a volume measurement by the gas meter before the energy source is transferred to the periphery and its pressure is finally reduced on site by control systems to between 23 and 700 millibars . All pre-processing steps are carried out under strict control, both by a central control center and by technical field service employees.  

Information security right through to door opening  

As a network operator, e-netz Südhessen is classified as a critical infrastructure (KRITIS). For these organizations and institutions, which are of vital importance to the state, the Federal Ministry of the Interior has defined strategic requirements designed to ensure high availability and security – for example, of IT systems. Based on these requirements, the Entega subsidiary defined specific requirements for internal information security. "We wanted to be able to monitor entrance doors and control cabinets in all gas pressure regulating and metering stations," says Jürgen Nagel, who is responsible for the electrical systems in e-netz Südhessen's gas and water operating facilities. When was a control cabinet door opened and where? This information had to reach the network control center without the need for costly electrical engineering upgrades in the decentralized stations.  

IM12-CCM replaces complex roller switches  

"I didn't think door contact switches were reliable enough, and roller switches would have been too costly," says Nagel, describing the selection process. "You have to drill holes in the cabinets, bend the metal in some cases, or work with small tools." The tests were more successful with TURCK's IM12-CCM control cabinet monitor, a compact device for direct top-hat rail mounting, whose internal sensors measure three values at once: temperature, humidity, and the distance to the door. "The device is ideal for our purposes: clip it in , connect two wires and apply voltage, pull two wires to the PLC – and you're done."  

e-netz Südhessen now uses three interconnected control cabinet monitors in its largest transfer station. With the help of reed contacts, the two downstream devices transmit their signals to the primary IM12-CCM, which in turn forwards the information to the PLC. This allows employees in the network control center to see when a control cabinet door has been opened at the station. This simple way of retrofitting control cabinets with internal monitoring caught on in Darmstadt. Electricians are now also using the devices in district heating and biogas plants.  

Temperature measurement   

Most gas transfer stations and district heating systems already have air conditioning technology that prevents electronic devices from overheating. Components installed in the control cabinet include frequency converters and power supplies for pressure transmitters and temperature measurement. In addition, there are isolating amplifiers, for which e-netz Südhessen has relied on TURCK for more than 30 years. Nevertheless, not all stations are air-conditioned yet. In one of the transfer stations, Jürgen Nagel therefore also uses the temperature measurement of the IM12-CCM. "The control cabinet is located in the boiler room, where it can get very warm despite insulation; and especially with a PLC or a power supply unit, I prefer it to be a little cooler."  

If the temperature exceeds 42 °C, the control cabinet monitor sends a signal to the PLC. Nagel programmed this limit value into the IM12-CCM using an IO-Link USB adapter. Alternatively, the parameterization could have been carried out using FDT software such as Pactware or via Quick- Teach directly on the device. e-netz Südhessen also benefits from the internal data logger of the 12.5 mm narrow control cabinet monitor, which time-stamps values and stores them for up to two years. This allows technicians to trace the conditions under which abnormal temperature values occurred at any time.  

Simple retrofitting of Condition Monitoring   

Condition Monitoring is not only relevant as a requirement for machines and storage areas, but also affects control cabinets. This is demonstrated by the information security management of e-netz Südhessen AG, which uses TURCK's IM12-CCM to monitor the door closure of control cabinets in decentralized facilities and thus detects unauthorized access. Where unstable climatic conditions endanger the availability of electronic devices, the sensors installed in the device for measuring temperature and humidity also pay off. An important factor for the e-netz specialists during the retrofitting process was the time and effort involved in commissioning. TURCK's IM12-CCM impressed with its simple installation and uncomplicated Teach functions.

Customer | www.e-netz-suedhessen.de