Method and device for monitoring circuit breaker

Patent metadata

Field	Value
Publication number	US-2016299192-A1
Application number	US-201615185614-A
Country	US
Kind code	A1
Filing date	Jun 17, 2016
Priority date	Sep 29, 2014
Publication date	Oct 13, 2016
Grant date	—

Abstract

Embodiments of the present disclosure provide a method for monitoring a circuit breaker, comprising the following steps: obtaining a characteristic force associated with an actuating mechanism of the circuit breaker over the time; and determining the time point when the closing and/or opening of the circuit breaker occurs by identifying a variation of the force. The step of determining further comprises determining the moment when a variation increase of the characteristic force occurs as the time point of the closing of the circuit breaker; and determining the moment when a variation decrease of the characteristic force occurs as the time point of the opening of the circuit breaker. The method can be used to accurately on-line monitor the closing and opening time point of the circuit breaker.

First claim

1 . A method for monitoring a circuit breaker comprising an actuating mechanism for actuating the closing and opening of a movable contact of the circuit breaker; the method comprising the following steps:
obtaining a characteristic force associated with the actuating mechanism over the time; and determining the time point when the closing and/or opening of the circuit breaker occurs by identifying a variation of the force; wherein the step of determining further comprises determining the moment when a variation increase of the characteristic force occurs as the time point of the closing of the circuit breaker; and determining the moment when a variation decrease of the characteristic force occurs as the time point of the opening of the circuit breaker.

2 . The method according to claim 1 , wherein the characteristic force is any of the followings:
a contact force which is directly applied on a linkage mechanism of the actuating mechanism by a movable contact of the circuit breaker; an internal force subjected by any rod of a linkage mechanism of a actuating mechanism; a resultant force subjected by either end of any rod of the linkage mechanism; a component of the resultant force subjected by either end of any rod of the linkage mechanism, which component is in the direction of the contact force; a component of the resultant force subjected by either end of any rod of the linkage mechanism, which component is perpendicular to the direction of the contact force; a resultant force subjected by any pivot point for the linkage mechanism; a component of the resultant force subjected by any pivot point for the linkage mechanism, which component is in the direction of the contact force; a component of the resultant force subjected by any pivot point for the linkage mechanism, which component is perpendicular to the direction of the contact force.

3 . The method according to claim 1 , wherein the step of obtaining comprises computing a contact force which is directly applied on a linkage mechanism of the actuating mechanism by a movable contact of the circuit breaker, by a sensored force associated with the actuating mechanism;
wherein the determining step comprises determining the time point when the closing and/or opening of the circuit breaker occurs by identifying a variation of the computed contact force.

4 . The method according to claim 3 , wherein the contact force is computed by the sensored force which is sensored at any pivot point of the linkage mechanism.

5 . The method according to claim 1 , wherein the variation of the characteristic force is identified based on the magnitude of the force and/or the rate of force variation.

6 . The method according to claim 5 , wherein the step of obtaining comprising:
sampling a number of values of the characteristic force at different time points from a starting point, and obtaining a first array F [a 1 , a 2 , . . . a 1 , . . . a n ] representing the values of the characteristic force at the sampling time points, and a second array T [t 1 , t 2 , . . . t i , . . . t n ] representing the corresponding sampling time points, wherein “a i ” is the value of the sampled characteristic force for the i time sampling, “n” is the number of the sampling, “t i ” is the time point for the i time sampling.

7 . The method according to claim 6 , wherein the determining step comprising identifying an item (a i ) from the first item in the first array F which value reaches or exceeds a first predetermined force value (V1) for the first time, and determining the time point (t i ) in the second array T corresponding to the identified item (a i ) from the first array F as the time point of the closing of the circuit breaker.

8 . The method according to claim 6 , wherein the determining step comprising identifying an item (a i ) from the first item in the first array F which value is at or below a second predetermined force value (V2) for the first time, and determining the time point (t i ) in the second array T corresponding to the identified item (a i ) from the first array F as the time point of the opening of the circuit breaker.

9 . The method according to claim 6 , wherein the determining step comprising identifying an item (a i ) from the first item in the first array F which meets the following condition for the first time:
there are just a predetermined number (V 3 ) of continuous items from a preceding item to the identified item (a i ) in the first array F, wherein each of the continuous items has a value at or below a second predetermined force value (V2); and then determining the time point (t i−V3+1 ) in the second array T corresponding to the first item of the predetermined number (V 3 ) of continuous items in the first array F as the time point of the opening of the circuit breaker.

10 . The method according to claim 6 , wherein the step of obtaining further comprising computing and obtaining a third array dF [(a 2 −a 1 )/(t 2 −t 1 ), (a 3 −a 2 )/(t 3 −t 2 ), . . . (a i −a i−1 )/(t i −t i−1 ), . . . (a n −a n−1 )/(t n −t n−1 )] representing the rate of force variation, in which each item refers to the force variation rate during the adjacent two samplings.

11 . The method according to claim 9 , wherein the determining step comprising:
identifying an item (a i ) from the first item in the first array F which meets the following both conditions for the first time:
the value of the identified item (a i ) reaches or exceeds a first predetermined force value (V1);
among the several items in the third array dF which are at or close to a corresponding item ((a i −a i−1 )/(t i −t i−1 )) in the third array dF, there is an item ((a j −a j−1 )/(t j −t j−1 )) which value reaches or exceeds a first predetermined force change rate value (V4), wherein the corresponding item ((a i −a i−1 )/(t i −t i−1 )) in the third array dF refers to the force change rate at the time point when the identified item (a i ) in the first array F is sampled;
and then determining the time point (t i ) in the second array T corresponding to the identified item (a i ) from the first array F as the time point of the closing of the circuit breaker.

12 . The method according to claim 9 , wherein the determining step comprising:
identifying an item (a i ) from the first item in the first array F which meets the following both conditions for the first time:
the value of the identified item (a i ) is at or below a second predetermined force value (V2);
among the several items in the third array dF which are at or close to a corresponding item ((a i −a i−1 )/(t i −t i−1 )) in the third array dF, there is an item ((a j −a j−1 )/(t j −t j−1 )) which absolute value reaches or exceeds a second predetermined force change rate value (V5), wherein the corresponding item ((a i −a i−1 )/(t i −t i−1 )) in the third array dF refers to the force change rate at the time point when the identified item (a i ) in the first array F is sampled;
and then determining the time point (t i ) in the second array T corresponding to the identified item (a i ) from the first array F as the time point of the opening of the circuit breaker.

13 . The method according to claim 5 , wherein
the step of obtaining comprises obtaining a profile of the value of the characteristic force over the time; and the step of determining comprises determining the time point when the closing and/or opening of the circuit breaker occurs by identifying a variation in the profile.

14 . The method according to claim 13 , wherein the step of determining comprises processing the profile with wavelet transforming, and determining the time point when the

Assignees

• Abb Technology Ltd

Inventors

• Zhuang Zhijian
• Ye Xin
• Lu Congwen

Classifications

• G01R31/327 Primary

  Testing of circuit interrupters, switches or circuit-breakers · CPC title

• G01R31/3274 Primary

  Details related to measuring, e.g. sensing, displaying or computing; Measuring of variables related to the contact pieces, e.g. wear, position or resistance (measuring contact resistance G01R27/205) · CPC title