Method for determining a cause of a voltage outage load-side from a circuit breaker, auxiliary unit for a circuit breaker, electric system comprising a circuit breaker and one such auxiliary unit

Patent metadata

Field	Value
Publication number	US-10020153-B2
Application number	US-201414483714-A
Country	US
Kind code	B2
Filing date	Sep 11, 2014
Priority date	Sep 12, 2013
Publication date	Jul 10, 2018
Grant date	Jul 10, 2018

Abstract

In this method, the voltage outage load-side is an opening of the circuit breaker, and the circuit breaker is able to interrupt the flow of electric current in an electric connection including an electric conductor. The auxiliary unit comprises a current sensor for measuring the intensity of the current flowing in the electric conductor and a first detection means for detecting the voltage outage load-side from the circuit breaker. The method comprises the following steps: measuring the intensity of the current flowing in the electric conductor, detecting the voltage outage load-side from the electric circuit breaker, determining a cause of the detected voltage outage load-side from the circuit breaker, said cause being selected from the group consisting in: an electric overload, a short-circuit and a voltage drop.

First claim

The invention claimed is:

1. A method for determining a cause of a voltage outage load-side from a circuit breaker by an auxiliary unit, the voltage outage load-side corresponding to an opening of the circuit breaker or to a voltage drop at the input of the circuit breaker below a first reference voltage value, the circuit breaker being in an open position able to interrupt flow of an electric current in an electric connection including at least one electric conductor,
the auxiliary unit comprising at least one current sensor configured to measure intensity of the current flowing in a respective electric conductor and a first detector configured to detect the voltage outage load-side from the circuit breaker, the method comprising the following steps:
a) measuring, with said current sensor, the intensity of the current flowing in said or each electric conductor;
a2) calculating, depending on the intensity or intensities measured in step a), a value of a heating-up of a second detector of an electric overload, the second detector being comprised in the circuit breaker;
a3) calculating, with the auxiliary unit, a maximum value of the intensities measured during a predetermined lapse of time;
b) detecting, via the first detector, the voltage outage load-side from the electric circuit breaker; and
c) determining a cause of a detected voltage outage load-side from the circuit breaker, with the auxiliary unit and depending on
the intensity or intensities measured by said current sensor,
a first threshold value set to a heating-up value of the second detector corresponding to a current comprised between 100% and 120% of a rated current of the circuit breaker, and
a second threshold value comprised between 3 and 10 times the rated current of the circuit breaker,

the determining step including comparing the maximum value of the intensities measured with the second threshold value and, when the calculated maximum value of the intensities measured is lower than the second threshold value, a second cause of the voltage outage load-side from the circuit breaker corresponding to a short-circuit is determined, whereas otherwise the calculated heating-up value is compared with the first threshold value, and a first cause of the voltage outage corresponding to an electric overload is determined when the calculated heating-up value is higher than the first threshold value, while otherwise a third cause of the voltage outage corresponding to a manual opening of the circuit breaker and/or to a drop/cut off of a voltage arriving on input terminals of the circuit breaker is determined.

2. The method according to claim 1 , wherein subsequently to step a2), the auxiliary unit carries out the following steps:
a3) comparing the value of the heating-up calculated with a third threshold value; and
a4) generating an alarm signal when the value of the calculated value of the heating-up is greater than the third threshold value.

3. The method according to claim 2 , wherein
the first threshold value is greater than the third threshold value.

4. The method according to claim 1 , wherein subsequently to step a2), the auxiliary unit carries out the following steps:
a3′) comparing the value of the heating-up calculated with a third threshold value and with a fourth threshold value, less than the third threshold value; and
a4′) generating an alarm signal from a moment when the calculated value of the heating-up is greater than the third threshold value and as long as the calculated value of the heating-up is greater than the fourth threshold value.

5. The method according to claim 1 , wherein subsequently to the determining step c), the auxiliary unit carries out the following step:
d) transmitting a message containing a first datum corresponding to the presence of a voltage load-side from the circuit breaker and a second datum corresponding to the cause of the voltage outage load-side from the circuit breaker, to a concentrator.

6. An auxiliary unit for an electric circuit breaker, the circuit breaker being, in an open position, capable of interrupting flow of an electric current in an electric connection including at least one electric conductor, the circuit breaker comprising at least a second detector configured to detect an electric overload, the auxiliary unit comprising:
at least one current sensor configured to measure intensity of the current flowing in a respective electric conductor;
a first detector configured to detect a voltage outage load-side from the circuit breaker, the voltage outage load-side corresponding to an opening of the circuit breaker or to a voltage drop at the input of the circuit breaker below a first reference voltage value;
a first calculator configured to calculate a heating-up value of the second detector, depending on the intensity measured by said current sensor;
a second calculator configured to calculate a maximum value of intensities measured during a predetermined lapse of time; and
a determining device configured to determine a cause of the voltage outage load-side from the circuit breaker, depending on
the intensity or intensities measured by the current sensor,
a first threshold value set to a heating-up value of the second detector corresponding to a current comprised between 100% and 120% of a rated current of the circuit breaker, and
a second threshold value comprised between 3 and 10 times a rated current of the circuit breaker,

the determining device being configured to compare the maximum value of the intensities measured with the second threshold value and, when the calculated maximum value of the intensities measured is lower than the second threshold value, a second cause of the voltage outage load-side from the circuit breaker corresponding to a short-circuit is determined, whereas otherwise the calculated heating-up value is compared with the first threshold value, and a first cause of the voltage outage corresponding to an electric overload is determined when the calculated heating-up value is higher than the first threshold value, while otherwise a third cause of the voltage outage corresponding to a manual opening of the circuit breaker and/or to a drop/cut off of a voltage arriving on input terminals of the circuit breaker is determined.

7. The auxiliary unit according to claim 6 , the circuit breaker including an input terminal for the current and an output terminal for the current for each electric conductor, wherein the first detector comprises at least one voltage sensor configured to measure the voltage delivered to a respective output terminal of the circuit breaker, and the first detector is configured to detect the voltage outage load-side from the circuit breaker in response to the voltage measured by the voltage sensor being less than a second reference voltage value during a predetermined time interval.

8. The auxiliary unit according to claim 7 , further comprising:
a third calculator configured to calculate an electric power and an electric energy crossing each corresponding conductor from the intensity and voltage values respectively measured by said current sensor and said voltage sensor; and
a communication member configured to transmit the intensity and voltage measured values and the calculated energy and power values to a concentrator.

9. The auxiliary unit according to claim 6 , the circuit breaker including an input terminal for the current and an output terminal for the current for each electric conductor, wherein the first detector comprises at least one voltage sensor configured to measure the voltage delivered to a respective output terminal of the circuit breaker, and the first detector is configured to calculate a derivative of the measured voltage and to detec

Assignees

• Schneider Electric Ind Sas

Inventors

• Vincent Francois
• Tian Simon

Classifications

• H01H71/125 Primary

  characterised by sensing elements, e.g. current transformers (for differential protection H01H83/144) · CPC title

• H01H71/462

  housed in a separate casing, juxtaposed to and having the same general contour as the main casing (for neutral conductor H01H71/002) · CPC title

• H01H2071/042

  with different indications for different conditions, e.g. contact position, overload, short circuit or earth leakage · CPC title

• H02H3/38

  responsive to both voltage and current; responsive to phase angle between voltage and current · CPC title

• H02H3/10

  additionally responsive to some other abnormal electrical conditions · CPC title