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On-line partial discharge monitoring system for rotating machines

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The new MONGEMO on-line partial discharge (PD) monitoring system from Omicron 
continuously assesses the dielectric condition of stator insulation in rotating machines under load, such as turbo generators, hydro generators and electrical motors. The permanently-installed system collects and analyses PD data over time and identifies insulation defects that could lead to dielectric failure and machine outages.

The MONGEMO PD monitoring system is customisable to match the exact requirements of various rotating machines. It consists of coupling capacitors for PD detection, a 4-channel PD acquisition unit, and a central computer with monitoring and PD analysis software. With the convenient web interface, users can remotely configure the monitoring system, view real-time data and historical trends, and analyse the collected raw data.

The high PD measurement sensitivity of the MONGEMO monitoring system is based on advanced Omicron technology for noise suppression and PD source separation. Multiple PD sources are distinguished from external noise through synchronous multi-channel measurements and advanced methods like 3PARD (3-Phase Amplitude Relation Diagram) and automatic cluster separation for convenient visual evaluation.

MONGEMO monitoring software automatically displays real-time data as well as historical trend diagrams of statistical parameters for each monitored machine, such as PD magnitude and PD pulse frequency. Users are also provided with an event log that displays warnings and alarms when PD activity reaches or exceeds pre-defined threshold values. The related raw PD data can be evaluated further using the system’s expert software for in-depth PD analysis. The actionable data allows users to assess the risk of dielectric failure in their machines and to optimise their maintenance and asset planning.

MONGEMO supports multiple industrial communications standards. This enables PD monitoring data from MONGEMO to be easily exported to SCADA systems. The system also displays monitoring data from other third-party devices, such as temperature sensors.

Omicron provides users with complete guidance and support during the design, set-up and use of the MONGEMO monitoring system. This includes on-site consultations to evaluate monitoring needs; customised system design, installation, commissioning and training; as well as support with data evaluation and reporting.

Statistics for rotating electrical machines show that a major source of their failure is linked to defects in stator insulation. A majority of these defects can be detected early through the continuous, permanent monitoring of PD activity. PD occurs in the stator insulation system of generators and motors, where local electric field stress exceeds the local electrical strength.

The insulation materials typically used for rotating machines are resistant to a certain level of PD. However, an increase in PD activity over time often indicates insulation defects and degradation caused by operational stress factors and aging processes. If left unattended, this could lead to failure and serious consequent damage.

On-line PD monitoring is a well-established technique used to continuously assess the condition of a stator winding insulation system. The actionable data helps organisations to optimise their asset management, maintenance efforts and investment planning. Machine failures can be avoided through the timely implementation of maintenance and repair measures to ensure a longer service life.

Omicron electronics

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