TOTUS uses integrated intelligence and analytics to provide reliable and intuitive monitoring for partial discharge in bushings.
According to statistics published by IEEE, IEC and CIGRE, bushings contribute to roughly 15-30% of power transformer failures globally.
In over 40% of cases the transformer failure resulted in catastrophic consequences such as fire, tank rupture and explosions. CIGRE TB 755 reports:
bushings cause 5% to 50%, of transformer failures
bushing failures are the most common cause of transformer fires and can cause huge collateral damage in the switchyard
30% of generator step-up transformer failures are caused by a bushing malfunction
Online monitoring of bushings, through monitoring of internal insulation (capacitance / Tan Delta or Power Factor) and the internal electrical activity (Partial discharges) enables asset managers to detect a fault at its very preliminary stage, allowing action to be taken before reaching a critical and irreversible stage.
TOTUS allows for correlation and causation to determine transformer failure modes, driving prescriptive actions. We monitor the following on bushings:
Thanks to monitoring a combination of leakage current & partial discharges we have saved over $10M in damages to bushings for our customers including RIP bushings
RIP bushings are made with a void-free impregnation process, designed for a Partial Discharge free operation. However, a combination of extraordinary operating and external events can result in PD in the bushings.
The resin material is not able to withstand the PD activity and will lead to fast degradation and short circuit.
Monitoring PD within the bushings is critical and allows early detection of faults, allowing for fast diagnoses and action. The Image to left shows PD trending in bushings on a RIP bushing.
Early detection of partial discharge can significantly improve risk diagnosis, driving quicker accurate decision making.
Recognising the PD pattern makes it possible to understand the nature of the defect and correlate this with leakage current to determine the best technical action or test. In over 70% of cases monitored by Camlin PD was a factor, often in early stages. Partial discharge monitoring identifies:
To learn more about our capabilities in partial discharge monitoring and detection methods, click below to read our customer case study
A successful online partial discharge testing program can help to inform prescriptive actions for asset managers. When selecting a partial discharge monitoring solution, it is important to stick to four key principles:
Ultimately, with reliable partial discharge monitoring, asset managers can screen their power transformer fleet and focus only on those transformers with active and repetitive PD.
"Monitoring of Partial Discharges can be easy to apply and understand if put in the right context, correlation of PD with other parameters can help to provide more accurate prescriptive actions and decision making."
Dr Marco Tozzi - Senior Product Manager, Camlin Power
Watch Camlin expert Marco Tozzi talk through the key benefits of monitoring PD in Bushings and the benefits to the utility.
Camlin provided an online bushing and partial discharge monitoring solution that was installed on a single-phase transformer bank.
Online monitoring pinpointed an incremental increase in bushing capacitance, accompanied by occurrence of an isolated high energy event.
Click below to access the full case study.
Why do Bushings fail? Bushing failures are related to a loss of insulation properties, i.e. the inability to act as a “ideal” insulating medium between the high voltage and ground. This can happen for multiple reasons such as:
1. Ingress of moisture
2. Ingress of solid contaminants
3. Oil leakage (OIP type)
4. Electrical short circuit between the layers
5. Surface cracks on the porcelain
6. Presence of voids, cracks & delamination between layers
To access our webinar on bushing failure modes and detection methods, click below.
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