Online and offline Partial Discharge
Partial discharge (PD) occurs in the stator insulation system of rotating machines, where local electric field stress exceeds the local electrical strength. Compared with other dielectric tests, the differentiating character of partial discharge measurements allows localized weak points of the insulation to be identified.
PD measurements based on IEC 60034-27 standards can be performed on motors and generators either on-line during regular load service operation or off-line by energizing each winding successively during standstill of the machine.
Generally, several different partial discharge sources are present and active within the stator winding insulation at the same time. The key to successful PD measuring in stator windings is the separation of parallel active PD sources and the distinction between harmful PD, normal PD occurrences and outer noise, inevitably present in industrial surroundings.
This is best achieved by synchronous, multi-channel partial discharge measurement. This separates internal PD sources from each other and from noise signals. PD sources are evaluated individually within the stator winding.
The insulation is the most sensitive part of rotating machines. The lifetime of a stator winding depends on how effectively the electrical insulation can prevent any occurrence of winding faults.
Weak spots can already occur in the insulation during manufacture or impregnation with cast resin, through the stresses of daily operation (for example in the form of soiling) or general aging.
With capacitance and dissipation factor measurements, also known as tan-delta measurements, changes in the insulation can be diagnosed. Aging processes, changes in the structure of the insulation or moisture ingress can, for example, increase the dissipation factor. The increase in the dissipation factor during the “tip-up test” reflects the condition of the insulation.
Component misalignment is one of the primary issues facing coupled machinery. By correctly aligning these components on a regular basis, operators can achieve significant reductions in maintenance expenses and overall operating costs. Laser alignment relies on information from laser receivers and transmitters to identify misaligned components with a high level of accuracy. Identifying these misalignments ensures that technicians can properly re-align components in accordance with ISO 9001:2015.
Vibration analysis is a process of looking for anomalies and monitoring change from the established vibration signature of a system. The vibration of any object in motion is characterized by variations of amplitude, intensity, and frequency. These vibration signatures can be correlated to physical phenomena, making it possible to use vibration data to gain insights into the health of equipment.