EWE AG in Oldenburg, Germany is an important company for power, environment, and telecommunications.
EWE supplies over 700 thousand customers with natural gas and also operates two gas storage facilities in Northern Germany which are located in salt domes – 21 caverns with 700,000 m³ and 13 billion kWh of power.
EWE covers its yearly natural gas requirement with constant procurement quantities. During off-peak periods, such as in the summer, the gas is pumped under pressure into the salt dome and is later extracted from here during high-demand periods.
In order to ensure the power supply, the systems must always be available. Therefore, surge protection is especially important.
Sensors and actuators as well as valves and drives are installed outdoors, while plant control and process visualization are located in the control room.
All information is sent to the main computer in Oldenburg via long-distance data transmission.
For the most part, the power supply protection concept is designed with two stages: FLT-PLUS lightning arresters in main distributions and VAL-MS surge arresters in sub-distributions and control cabinets.
A high level of availability must be ensured for key parts of the system, they are therefore equipped with uninterruptible power supply units (UPS). In turn, these UPS units are protected with VAL-MS surge arresters.
Many signal transmissions are designed as Ex ia circuits. These intrinsically safe circuits are protected with TERMITRAB TT-EX(I)-24DC. The two-stage protective circuits with powerful surge arresters and fast-responding suppressor diodes are set up in the arresters, which are only 6.2 mm wide.
Thanks to the low protection level and high discharge capacity of 10 kA, the electronics are safely protected in the control cabinet and only occupy a small amount of space.
TERMITRAB TT-2-PE-24DC devices protect the signal circuits which do not require intrinsic safety. The communication interfaces are protected against surge voltages by MODUTRAB MT-2FM-RJ12.
This therefore provides a seamless protection concept for operating equipment in the field and the control systems indoors: all system components are reliably protected.