Electrical protection unit including a current limiter device

Patent metadata

Field	Value
Publication number	US-2018366289-A1
Application number	US-201815944078-A
Country	US
Kind code	A1
Filing date	Apr 3, 2018
Priority date	Jun 16, 2017
Publication date	Dec 20, 2018
Grant date	—

Abstract

An electrical protection unit A including a main conductor and, for each main conductor, a current limiter device connected in series with the main conductor to limit the current when a current or temperature threshold is exceeded, the limiter device including an element made of a material having a positive temperature coefficient, called PTC, and being capable of controlling a device for tripping the mechanism M for opening the contacts of the protection unit D, to cause the opening of the contacts of the unit when the threshold is exceeded leading to a change of state of the element between a low resistance state and a high resistance state. The PTC element includes the trip device, in such a way that this element itself provides the functions of fault current limitation and of tripping the mechanism for opening the contacts.

First claim

1 . An electrical protection unit comprising at least one main conductor and, for the or each main conductor, at least one current limiter device connected in series with said main conductor in order to limit the current when a current or temperature threshold is exceeded, said limiter device including a PCT element made of a material having a positive temperature coefficient and being capable of controlling trip means for tripping the mechanism for opening the contacts of the protection unit, so as to cause the opening of the contacts of the unit when said threshold is exceeded leading to a change of state of said element between a low resistance state and a high resistance state,
wherein said PTC element includes the trip means, in such a way that said element itself provides the functions of fault current limitation and of tripping the mechanism M for opening the contacts.

2 . The electrical protection unit according to claim 1 , wherein said PTC element further includes means for detecting overload faults and means for detecting short-circuit faults.

3 . The electrical protection unit according to claim 1 , wherein the trip means are controlled by the variations in size, along a preferred direction, of the PTC element, during the change of state, said variation in size being capable of causing a portion of the PTC element to move in the direction of a trip bar belonging to the trip means.

4 . A protection unit according to claim 3 , wherein trip means are controlled by the variation in the thickness of the PTC element during the change of state.

5 . The electrical protection unit according to claim 3 , wherein amplification means configured to exert, based on a small movement of a portion of the element, an applied force of higher intensity.

6 . The electrical protection unit according to claim 1 , wherein the limiter device includes multiple PTC elements stacked along the preferred direction and electrically connected in parallel.

7 . The electrical protection unit according to claim 6 , wherein the number of stacked elements is comprised between two and ten.

8 . The electrical protection unit according to claim 7 , wherein the number of stacked elements is four.

9 . The electrical protection unit according to claim 3 , wherein means for limiting the volume expansion along at least one direction other than the preferred direction.

10 . The electrical protection unit according to claim 9 , wherein the means include a metallization produced on at least one face of said element, likely to promote the adhesion of the filled polymer.

11 . The electrical protection unit according to claim 10 , wherein the thickness of said metallization is greater than 50 μm when said metallization is made of copper, and greater than 35 μm when said metallization is made of nickel.

12 . The electrical protection unit according to claim 1 , wherein the limiter device further includes at least one shunt that is connected in parallel with at least one PTC element, respectively, and configured to set the maximum value of the limited current after the transition of the PTC element.

13 . The electrical protection unit according to claim 12 , wherein the resistive value of the shunt is comprised between ten times and twenty times the value of the corresponding PTC resistance at room temperature.

14 . The electrical protection unit according to claim 1 , wherein the limiter device further includes at least one component, called an overvoltage protector, that is connected in parallel with at least one PTC element, respectively, and is intended to limit potential overvoltages that are liable to damage the PTC component.

15 . The electrical protection unit according to claim 1 , wherein each PTC element is produced on the basis of a semi-crystalline polymer.

16 . The electrical protection unit according to claim 15 , wherein said electrical protection unit is a miniature circuit breaker.

Assignees

• Schneider Electric Ind Sas

Inventors

• Rapeaux Michel
• Domejean Eric

Classifications

• H02H3/025

  Disconnection after limiting, e.g. when limiting is not sufficient or for facilitating disconnection · CPC title

• H02H9/026 Primary

  Current limitation using PTC resistors, i.e. resistors with a large positive temperature coefficient · CPC title

• H01H2033/163

  using PTC elements · CPC title

• H02H1/0015

  Using arc detectors · CPC title

• H01H71/7427

  Adjusting only the electrothermal mechanism · CPC title