Vacuum Tap Changer Pressure Pulse Diagnostics
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Solution Overview
Problem
Vacuum on-load tap changers face challenges in detecting slow operation and potential failures due to arcing, leading to overheating, malfunctioning, and safety risks such as explosions or fires, which existing monitoring systems do not adequately address.
Innovation Solution
A method and monitoring system that utilize a pressure sensor to detect pressure signatures and determine switch times, activate alarms for malfunctioning or unsafe operations, and monitor insulating fluid levels to prevent overheating and ensure safe operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pressure sensor is used to monitor the housing, then slow operation and gas-producing events can be detected, but the system complexity increases
Solution Approach 1:
A pressure sensor is introduced as an intermediary device to detect slow operation and gas-producing events by measuring pressure changes in the housing, thereby enabling reliable detection without directly monitoring the complex internal switching mechanisms
Solution Approach 2:
The mechanical monitoring of switch operation is replaced by using pressure sensor measurements to detect operational status, substituting a simple pressure-based detection system for complex mechanical state monitoring
2Reliability
If vacuum interrupters are used to prevent arcing, then electrical contact wear is reduced, but gas production and pressure changes occur during operation
Solution Approach 1:
The pressure sensor provides continuous feedback on gas production during vacuum interrupter operation, allowing the system to monitor and respond to abnormal gas generation that could indicate malfunction or unsafe conditions
Solution Approach 2:
The gas production, which is a harmful byproduct of vacuum interrupter operation, is converted into a useful monitoring signal through pressure measurement, enabling detection of operational status and potential failures
3Productivity
If the diverter switch operates quickly, then productivity is improved, but slow operation can cause overheating and failure
Solution Approach 1:
Pressure measurements provide feedback on the timing and completion of switch operations, enabling detection of slow operations that could lead to overheating and allowing corrective action before failure occurs
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system effectively detects slow operations, gas-producing events, and unsafe conditions, enabling timely intervention to prevent failures and ensure the safe operation of vacuum on-load tap changers by continuously measuring pressure and determining switch times and fluid levels.
Implementation Method 1
at least one pressure sensor which measures the pressure in the housing
Implementation Method 2
The insulating fluid in the tank acts as electric insulator and as a coolant to remove the generated heat in the OLTC. The insulating fluid will also quench the arcs generated during switching.
Implementation Method 3
it is previously known to use vacuum switches or, in other words, vacuum interrupters for those switching operations where an arc arises
Data Source
Figure 1
Figure 2~3d
Figure 3e~3k
AI summary
The present invention relates to a method and a monitoring system (10), for monitoring a vacuum on-load tap changer (1). The tap changer (1) comprises a housing (2) with insulating fluid (3), a diverter switch (4) inside of the housing (2) and comprising at least one movable contact (MC, RC) and at least two vacuum interrupters (MV, RV), and at least one pressure sensor (5) which measures the pressure in the housing (2). The method, which is performed by a processing circuitry (11) in the system, comprises determining (S1) a pressure signature (14), including two succeeding peaks within a time interval, continuously (S2) measuring the pressure, detecting (S3) when the measured pressure shows the pressure signature (14), determining (S4), based on the measured pressure within the pressure signature (14), the time between the first rise in pressure and the second drop, and setting (S5) the determined time to represent the switch time of the diverter switch (4).