Keeping the power supply mains in order
The causes of failures in medium voltage cables may be a fault related to manufacture, installation, or overloading, or an environmental encumbrance. The partial discharge measurement measures and locates harmful partial discharges at the defective points of the isolation structure where the local dielectric rigidity is exceeded. The purpose of the measurement is to find faults developing in the cables, cable joints and terminals before failures occur.DEKRA Industrial's partial discharge measurement service is the first private service in this field to be offered commercially in Finland.
The benefits of measurement:
- Proactive cable inspection results in improved reliability.
- Preventive cable testing provides advance warning of faults. Developing faults in cables, extensions and terminals are found before the outage caused by the fault.
- Partial burst measurement can quickly identify and locate the point of failure.
The measuring instrument is OWTS M60, and the voltage source of the measuring system is attenuating alternating voltage [IEC 60060-3:2006]. The cable is disconnected from the rest of the network at both ends, then it is charged to the preset direct current, after which the voltage source disconnects and is replaced by a clamp. During the impact of the test voltage, the apparent charge [IEC 60270:2000] and location of the partial discharges are measured. Based on the attenuation of the test charge, the dissipation factor tan∂ is also measured. The results are recorded and documentation of the measurement is provided.
PRY-CAM Portable is a device developed and patented by the Prysmian Group. It is used to measure the electromagnetic field caused by partial discharges. The device is a portable and wireless instrument and is controlled using a tablet and wireless technology without galvanic contacts. The measurement is completed in normal operating conditions. When the subject is measured, the device is taken physically directly to the subject. PRY-CAM Portable is suitable for measuring the following medium and high voltage subjects, for example: cables, extensions, terminals, switchgear, transformers and electrical devices.
Using the PRY-CAM Portable, we are able to quickly and effortlessly conduct condition testing on subjects where making connections is difficult.
Our services also include VLF testing on new medium voltage cable connections. We can use the same equipment to conduct Tan Delta measurements on old cable connections in order to determine the general condition of the cable.