Apparatus for detecting arc flash

Patent metadata

Field	Value
Publication number	US-9825452-B2
Application number	US-201514801158-A
Country	US
Kind code	B2
Filing date	Jul 16, 2015
Priority date	Jul 16, 2015
Publication date	Nov 21, 2017
Grant date	Nov 21, 2017

Abstract

An apparatus may include a sensor housing, a light sensor disposed within the sensor housing, the light sensor arranged to generate a detection signal when light impinges on the light sensor, a sensor lens disposed at least partially outside the sensor housing, wherein a distal portion of the sensor lens extends a first distance above the sensor housing, the sensor lens being transparent, wherein light received from outside the sensor housing is transmitted to the light sensor; and a light emitter assembly disposed outside the sensor housing at a second distance above the housing less than the first distance.

First claim

The invention claimed is:

1. An apparatus, comprising:
a sensor housing;
a light sensor disposed within the sensor housing, the light sensor arranged to generate a detection signal when light impinges on the light sensor;
a sensor lens disposed at least partially outside the sensor housing, wherein a distal portion of the sensor lens extends a first distance above the sensor housing, the sensor lens being transparent, wherein light received from outside the sensor housing is transmitted to the light sensor; and
a light emitter assembly disposed outside the sensor housing, and arranged to extend a second distance above the sensor housing less than the first distance.

2. The apparatus of claim 1 , further comprising:
a signal line disposed at least partially within the sensor housing and coupled to the light sensor, the signal line to receive the detection signal and transmit the detection signal as an electric current; and
a relay connected to the signal line and having a shutoff component to terminate conduction through an external conduction line when value of the detection signal exceeds an arc flash detection threshold.

3. The apparatus of claim 1 , wherein the light emitter assembly comprises:
a light emitter housing;
a light emitting diode arranged to generate light as a test signal; and
a light emitter lens disposed on the light emitter housing and transparent to light emitted as a test signal, wherein the test signal is transmitted through the light emitter lens.

4. The apparatus of claim 3 , wherein the light emitter lens is disposed in a line-of-sight relationship with the sensor lens, wherein the test signal is transmitted by the sensor lens to the light sensor.

5. The apparatus of claim 3 , further comprising a circuit check arrangement having a test signal component to cause the light emitter assembly to periodically emit the test signal; and
a failure component to generate a failure signal when an intensity of light from the test signal detected by the light sensor falls below a threshold value.

6. The apparatus of claim 1 , wherein the sensor lens comprises a cylindrical structure having a cylinder axis extending along a perpendicular to a surface of the sensor housing.

7. The apparatus of claim 6 , wherein the sensor lens comprises a dome structure on a distal portion of the cylindrical structure away from the sensor housing.

8. The apparatus of claim 6 , wherein the sensor lens comprises an inner surface, the inner surface having a tapered structure, wherein the cylindrical structure has a first wall thickness in a first region and has a second wall thickness in a second region greater than the first wall thickness, the first region being disposed closer to the sensor housing than the second region.

9. The apparatus of claim 8 , wherein the inner surface is arranged to refract light incident from a side of the cylindrical structure downwardly toward the light sensor.

10. The apparatus of claim 6 , wherein the light sensor comprises a photovoltaic chip arranged along a horizontal at a first position within the sensor housing, wherein a first light beam received at a first angle with respect to the horizontal generates a first intensity in the light sensor equal to a second intensity generated in the light sensor when a second light beam is received at a second angle different than the first angle.

11. The apparatus of claim 6 , wherein the sensor lens is arranged to generate a first intensity at the light sensor for light received over a range of angles of incidence of +/−60 degrees with respect to the cylinder axis, wherein the first intensity lies between +/−10% of a second intensity of light received along the cylinder axis.

12. The apparatus of claim 6 , wherein the sensor lens is arranged to generate uniform intensity at the light sensor for light incident on the sensor lens over a 360 degree range of angles with respect to the cylinder axis at a fixed angle of incidence with respect to a plane of the housing.

13. An arc flash protection device, comprising:
an arc flash relay having a receiving component to receive a detection signal and a shutoff component to terminate conduction through a conduction line when a value of the detection signal exceeds a threshold; and
an arc flash sensor, comprising:
a sensor housing;
a light sensor disposed within the sensor housing, the light sensor arranged to generate the detection signal when light impinges on the light sensor;
a sensor lens disposed at least partially outside the sensor housing, wherein a distal portion of the sensor lens extends a first distance above the sensor housing, the sensor lens being transparent, wherein light received from outside the sensor housing is transmitted to the light sensor; and
a light emitter assembly disposed outside the sensor housing and arranged to extend a second distance above the sensor housing less than the first distance.

14. The arc flash protection device of claim 13 , wherein the light emitter assembly comprises:
a light emitter housing;
a light emitting diode arranged to generate light as a test signal; and
a light emitter lens disposed on the light emitter housing and transparent to light emitted as a test signal, wherein the test signal is transmitted through the light emitter lens.

15. The arc flash protection device of claim 13 , further comprising:
a circuit check arrangement having a test signal component to cause the light emitter assembly to periodically emit the test signal; and
a failure component to generate a failure signal when an intensity of light from the test signal detected by the light sensor falls below a threshold value.

16. The arc flash protection device of claim 13 , wherein the sensor lens comprises a cylindrical structure having a cylinder axis extending along a perpendicular to a surface of the sensor housing.

17. A method of protecting a component against an arc flash, comprising:
providing a light sensor within a sensor housing, the light sensor arranged to generate a detection signal when light impinges on the light sensor;
providing a sensor lens at least partially outside the sensor housing, wherein a distal portion of the sensor lens extends a first distance above the sensor housing, the sensor lens being transparent, wherein light received from outside the sensor housing is transmitted to the light sensor;
providing a light emitter outside the sensor housing, the light emitter extending a second distance above the sensor housing less than the first distance; and
generating a test signal from the light emitter, wherein the test signal is received by the light sensor.

18. The method of claim 17 , further comprising providing the sensor lens comprises with an inner surface having a tapered structure, wherein the sensor lens has a first wall thickness in a first region and has a second wall thickness in a second region greater than the first wall thickness, the first region being disposed closer to the sensor housing than the second region.

19. The method of claim 17 , further comprising:
causing the light emitter to periodically emit the test signal; and
generating a failure signal when an intensity of light from the test signal detected by the light sensor falls below a first threshold value.

20. The method of claim 19 , further comprising receiving a detection signal based upon light detected by the light sensor, and terminating conduction through a conduction line when a value of the detection signal exceeds a second threshold value.

Assignees

• Littelfuse Inc

Inventors

• Holmgaard Niels
• Seedorff Jakob

Classifications

• G01J1/44

  Electric circuits {(for command of an exposure part G03B7/02)} · CPC title

• H02H1/0023 Primary

  sensing non electrical parameters, e.g. by optical, pneumatic, thermal or sonic sensors · CPC title

• H01T2/02

  comprising a trigger electrode or an auxiliary spark gap · CPC title

• G01J2001/4238

  Pulsed light · CPC title

• G01J1/0411

  using focussing or collimating elements, i.e. lenses or mirrors; Aberration correction · CPC title