Keeping an eye on 53 wastewater pumps spread across 217 square kilometers
Creating transparency and data security without access to a telephone network is difficult. The cooperative sewage association in Handelsleben, Germany commissioned H&F Industry Data to handle the modernization of its sewage plant. The Siemens Solution Partner used the GSM/GPRS network to implement a solution that sets new standards.
The sewage plant in Haldensleben, located to the northwest of Magdeburg, collects the wastewater of the small town along with that of all of the surrounding communities over an area spanning some 217 square kilometers. The wastewater is treated in several steps so that it can be discharged into the Ohre river. Some of the separated sludge is used to generate methane and for agricultural purposes. The processes are fully automated. Manual intervention is only necessary during maintenance work or in case of failures. Previously, the sewage plant had relied on a diverse mixture of components and systems. However, to enable process intervention from anywhere and for preventive maintenance purposes, the mixture needed to be replaced with a homogeneous control system. Another essential goal involved the seamless integration of the 53 pump stations distributed across the sewage plant’s catchments.
Homogeneous control with a Siemens Partner
To handle the project, the cooperative sewage association in Haldensleben hired the services of H&F Industry Data from Rostock-Kavelsdorf. Employing a staff of some 120 employees, the company specializes in industrial and municipal process automation. Having equipped numerous sewage plants with automation technology, it has extensive experience in tasks like the one in Haldensleben. H&F Industry Data not only managed to find the best solution. Given the fact that linking the 53 outlying stations posed entirely new challenges in terms of data security, it even became a pilot project for the company.
A competent Siemens Solution Partner, H&F Industry Data performed the migration to the SIMATIC S7 controller. Via the TeleControl Professional system, a SIMATIC S7-300 at every pump location now communicates with the process control system in the sewage plant. Each PLC is equipped with a TIM3V-IE telecontrol communication module and is connected over an Industrial Ethernet cable with a GPRS router.
Process data as well as any fault messages and alarms are directly transmitted to the control center every five minutes. If the data link is interrupted, all events and archive values are buffered in the telecontrol station. Even if the control system is down, the plant continues to operate without data loss. Together with an uninterruptible power supply, gap-free process documentation is thereby ensured even in the event of a power failure. With the help of self-contained virtual private network (VPN) technology incorporating Scalance S security modules and GPRS routers, H&F set up a secure IPsec connection over the Internet.
Convenient maintenance and emergency servicing
“Previously, I had to drive to the sewage plant whenever we received an alarm signal to see what the problem was,” according to Frank Teggatz, the plant’s technical director. “Now I can log into the control center from my notebook at home and, thanks to the SIMATIC WinCC interface, have the system right in front of me as if I were sitting at my desk on-site.”
In addition to enabling process transparency and process data collection, linking all of the pump stations into one overall system also offers advantages in terms of maintenance and emergency servicing. For example, if the energy demand of a drive increases, it can be replaced during the next routine maintenance visit, before it fails and endangers the process. Also, if a process parameter reaches a critical value, an alarm is automatically triggered. During the day, a voice alert is sent over the telephone system. At night or on weekends, the system sends text messages.
A future-oriented solution
TeleControl Professional can be used practically anywhere there is a power connection. The on-site installation effort is minimal, the low operating costs are unbeatably low, and availability is ensured anywhere that data links can be established via mobile communications, the Internet or the customer’s own network.
The telecontrol system at the Haldensleben sewage plant demonstrated that it could handle more extensive systems incorporating several external stations. As a result, the next step is already being planned: the facility’s catchment area has further grown from 217 to 346 square kms, and the number of pump stations has increased from 53 to 69.