06/21/2021

Higher security for your bushings

Continuous online monitoring with MSENSE® BM / ETOS® BM


According to CIGRÉ, damage to high-voltage bushings is responsible for 17 percent of transformer failures. Since increasing demands on the grid require that transformers operate with maximum reliability, it is therefore all the more important to continuously record and evaluate the condition of the bushings - with MSENSE® BM / ETOS® BM.

MSENSE® BM / ETOS® BM online monitoring detects faults, aging and failure risks at an early stage and provides recommendations for action before the transformer is damaged.

Monitoring of high-voltage bushings usually takes place offline and once a year or even less frequent. The offline measuring also needs time and special measuring devices to be mobilized. This presents a high risk because during the long pauses between inspections, hidden deterioation damage and aging processes can develop negatively or escalate unnoticed with the result that a failure is not detected in time, with risks to the transformer itself and security of supply. The MSENSE® BM online monitoring system permanently monitors the condition of the bushings by measuring relevant variables directly on oil-impregnated paper bushings (OIP), resin-impregnated paper bushings (RIP) or resin-impregnated synthetic bushings (RIS/RIF) of voltage levels 66...420 kV*. This means: reduced costs due to predictable maintenance.

MSENSE® BM-C / ETOS® BM-C assesses the condition of the bushings based on changes in capacitance with a continuous tan delta measurement. The system compares the capacitance C1 of bushings obtained by very accurate voltage measurement with a precision capacitance CM. Breakdowns of the partial capacitances or even damage and aging of the internal insulation lead to changes in the capacitance which are signaled to the control center by the system as a warning or alarm.

MSENSE® BM-T / ETOS® BM-T assesses condition based on capacitance as well as loss factor (tan δ). As with MSENSE® BM-C / ETOS® BM-C, the capacitance is compared with the precision capacitance CM. In addition, MSENSE® BM-T / ETOS® BM-T considers the dissipation factor based on the calculated current vector from the reference voltage (line voltage). Changes of capacitance and dissipation factor indicate partial breakdowns of and damage to the internal insulation. In addition, damage to the conductor and the mechanical surface structure as well as heavy contamination will be detected. Also in this regard, the system provides the information as a warning or alarm to the control center.


*Higher voltage levels on request
 

f.micksch@reinhausen.com  
 
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