PQM in Banks
Project description Bank
In banks, insurance companies and other commercial buildings, increasing power problems with reference to harmonics, flickers, voltage peaks and similar effects have occurred in the past years. Network perturbations are often transported into the building from the medium voltage network.
The reason for internal power problems is the number of PCs and switched mode power supply units which are used. Due to the widely branched 5-conductor current networks, so-called “stray” currents can occur in ground wires. These are caused by incorrect grounding. These particularly lead to problems in data networks because they proceed in cables.
Flickering can lead to discomfort, headaches and tiredness among the members of staff. These disturbances are certainly not welcome because working in these types of buildings is made more difficult and may even become impossible without safe communication options. European norms have existed for several years for the assessment of network perturbations.
EN50160 regulates the power quality which must be provided by the energy supplier. The EN61000-2-4 provides the opportunity to measure the power quality within a building.
The power quality must be checked in a large bank at the feeders in accordance with EN50160 and at the sub-distributions in accordance with EN61000-2-4. Furthermore, the reasons for frequent problems in the data cables had also to be identified. The employees in building services should have access to the data at all times. Intranet was provided as the communication medium.
A total of 39 x UMG 510 were installed in the feeders and all important distributions for communication, such as in the server rooms etc. An important feature is the fourth current and voltage input on the instrument. Due to the installation of the fourth current transformer in the peak protective earth conductor, stray currents could be tracked down.
Potential differences due to incorrect grounding were identified using a separate measurement with the bridge between N and PE. The existing grounding errors could, therefore, be corrected. Obviously all of the data with reference to the power quality and all current related data were stored in the 128 MB memory of the UMG 510. The PAS510 software could be used to read the data at any time. An Ethernet TCP/IP interface was available for this purpose.
The reasons for the frequent loss of communication in the data network were found and important knowledge about the power quality was gained. The producers of harmonics could, therefore, be tracked down. Materials such as electronic controls or server supply units, which were previously destroyed due to network perturbations, could be protected with suitable power filters.
Furthermore, the monitoring of the power quality from the energy supplier was made possible in accordance with EN50160. A pleasing side-effect is the control of energy purchases or the power utility meter.