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Method for predictive online ablation monitoring of a circuit breaker

IP.com Disclosure Number: IPCOM000239430D
Publication Date: 2014-Nov-06
Document File: 2 page(s) / 125K

Publishing Venue

The IP.com Prior Art Database

Abstract

A method and a system to predict the probability of failure to break of a circuit breaker based on the online monitoring of the overlapping time and drive speed are proposed. The system monitors the overlapping time of a circuit breaker and conjointly the speed of the drive. From those parameters, the overlapping length is then determined. Using the previous logged drive speeds and the manufacturer information on the drive, a worst-case, i.e. shortest overlapping time is predicted. If this is lower than a given threshold an alarm is raised.

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Method for predictive online ablation monitoring of a circuit breaker

Idea: Yannick Maret, Martin Zlatanski

A method and a system to predict the probability of failure to break of a circuit breaker based on the online monitoring of the overlapping time and drive speed are proposed. The system monitors the overlapping time of a circuit breaker and conjointly the speed of the drive. From those parameters, the overlapping length is then determined. Using the previous logged drive speeds and the manufacturer information on the drive, a worst- case, i.e. shortest overlapping time is predicted. If this is lower than a given threshold an alarm is raised.

Basic prediction

A proposed basic predictive monitoring system shown in Figure 1 is simple but of limited reach as it makes use of the estimated overlapping time and of the speed variation of the drive. A subsystem is attached to the circuit breaker and monitor the overlapping time online while another subsystem is attached to drive and monitor the speed thereof. Both parameters are then conveyed to a central unit that process both information to estimate the overlapping length1. Conjointly, the speed of the drive is logged in the central unit memory. The central unit then get the fastest speed from its memory and compare it with the highest admissible speed as given from the manufacturer. The larger between both speeds is then used to predict the worst-case overlapping time from the latest overlapping length. The worst-case overlapping time is subsequently compared to a threshold2. An alarm is then raised accordingly.

The overlapping time as one input parameter may be monitored and estimated online as proposed in WO2014/14104. It is based on two couplers, one on each side of the breaking chamber. A transient signal is injected through one coupler and read out through the other. The overlapping length depends on another variable parameter, namely the speed of the drive. Even though the overlapping time is the crucial parameter that determines if arcs will affect the main contact (and thus damage the breaker), the aforementioned dependency limits the predictive power of an online monitoring system based solely on the overlapping time. It is the aim to overcome this limitation and to propose prediction of the overlapping time evolution.

The drive speed is based on an estimated travel curve that can be obtained from a plurality of auxiliary switches. More on the travel curve estimation can be found for example in US 2012/0053886 A1.

Figure 1 - block diagram of the predictive monitoring system

1 The speed of the main drive needs first to be converted to the speed of the contact system in order to calculate the real overlapping length. For particular circuit breakers an explicit conversion equation is available; its parameters are based on measurements performed during the design phase. To verify/calibrate those parameters, a fingerprint measurement can be performed during producti...