ELECTRICAL ARC FLASH MITIGATION SYSTEM

Abstract

The present invention includes devices and systems which detect an are flash electrical fault by calculating the rate of change in ultraviolet light, infrared light, and electrical current. This ensures compliance of plant electrical systems with 29 U.S.C. § 651 et seq. (1970), 29 CFR § 1910333, NFPA 70E and IEEE 1584 Standard. The devices and systems simultaneously provide a means for maintenance personnel to reduce long time, long time delay, short time, short time delay, instantaneous, ground fault, ground fault delay, and trip functions in the electronic trip units of typical low voltage breakers from a remote location outside the arc flash boundary. The devices and systems can also be controlled from a cloud-based computer which can be the host for the system operating software.

Claims

1. The present invention detects an arc flash electrical fault by calculating the rate of change in ultraviolet light, infrared light, and electrical current.

2. The devices and systems can also be controlled from a cloud-based computer which can be the host for the system operating software.

3. Provides protection for both the electrical equipment in the substation room and remote electrical systems being worked on by humans throughout the plant simultaneously.

4. The present invention also allows human interface with the arc flash mitigation system to reduce the amount of instantaneous, ground fault, short time, and long time energy from a remote location located outside the arc flash boundary where exposure to the electrical fault could produce damage to the electrical equipment and/or personal injury.

5. The present invention allows interruption of the formation of arc flash incident energy which can damage equipment or result in personal injury, thus limiting its magnitude to a value where there is little to no damage or injury.

6. The present invention is capable of detecting the inception of an impending arc flash event and providing signaling to an up-stream trip coil within 1.66 cycles of calculating an increase in the rate of change of the duv, dir and di which exceeds the user set limits.

7. The present invention is capable of detecting the onset of the arc flash incident energy and interrupting electrical current flow via a trip signal to the up-stream circuit breaker within 0.11666 seconds, or 7 cycles.

8. The present invention includes an arc flash breaker settings control system (ABC System).

9. The present invention comprises devices or systems that provide early detection and mitigation of an impending arc flash event.

Description

SUMMARY OF THE INVENTION

[0021] Congress passed the Occupational Safety and Health Act of 1970, defining a continuing general duty for employers to provide a safe and hazard free workplace. The Act is codified as 29 U.S.C. § 651 et seq. (1970). 29 CFR § 1910.333 further defines the treatment of electrical hazards in the workplace. 29 CFR § 1910.333 defines NFPA 70E as the consensus standard industrial facilities should use in analyzing their plants' electrical distribution systems for compliance with federal law. NFPA 70E, in turn, provides reference to IEEE 1584 Standard (2002 and 2018 editions). This provides detailed technical methodology for the analysis of plant electrical distribution systems and the calculation of electrical faults, breaker coordination, and arc flash energies.

[0022] The present invention addresses the needs described above. The present invention comprises devices or systems that provide early detection and mitigation of an impending arc flash event. In preferred embodiments, the present invention comprises devices which detect the change in ultraviolet light, infrared light, and electrical current in electrical equipment at the onset of an arc flash event. The devices and systems compare these rates of change in ultraviolet light, infrared light, and electrical current against normal rates of change associated with typical in-rush values occurring when energizing electrical equipment and ambient room lighting. In the event that a change in ultraviolet light, infrared light, and electrical current simultaneously exceeds the normal user defined values, the devices and systems send a trip signal to a lock-out relay and to the trip coil of the up-stream medium or low voltage breaker or circuit interrupting device. Due to the speed of operation, the devices and systems are capable of interrupting fault current forming at the contacts of the medium or low voltage circuit breakers or interrupting devices. Breaking the current path within the medium or low voltage circuit breakers results in arc flash incident energies far smaller than allowing the undetected flow of current to continue for two (2) seconds, the normal duration of an arc flash incident.

[0023] The devices and systems are specially adapted for the detection of ultraviolet light, infrared light, and electrical current in low voltage electrical equipment where the arc flash incident energy is much higher. Opening the up-stream breaker in the medium voltage system greatly reduces the potential for damage as the medium voltage system delivers a proportionally lower value of current during an arc flash event. The medium voltage breaker is typically more robust due to the application of vacuum bottle technology. Reduction in the amount and duration of fault current associated with the arc flash event reduces the potential for phase change of conductors and other metallic components. Eliminating the potential for phase change stops the arc flash energy from reaching the point where latent heat is produced, destroying conductors and significantly damaging electrical equipment. The devices and systems also provide a mechanism for maintenance personnel or system operators to lower their personal arc flash energy exposure while working on feeder branches of the electrical distribution system. The operation of this part of the system is conducted from outside the arc flash boundary and typically outside the electrical equipment room. The devices and systems provide instant feedback via the illumination of a blue push-to-test pilot light. The pilot light advises personnel that the electrical hazard has been reduced in the circuit they have selected. The devices and systems communicate that the breaker has been placed in the MAINTENANCE mode to an electronic supervisory system which can be monitored remotely and provide event and alarm logging if the breaker is in MAINTENANCE mode for an extended period of time. Event and alarm information is transmitted via a Cat. IV cable to an onboard Ethernet switch located in the Electrical Equipment Interface part of the ABC System (EIP). The Ethernet switch is in turn connected via a fiberoptic isolation device to the facility's computer system and then to the internet. The Electrical Equipment Interface part of the ABC System (EIP) also collects information on metered variables (i.e., Amps, Volts, kW, kWh, etc.) and transmits this information to the facility's computer and then to the internet. This part of the Electrical Equipment Interface part of the ABC System (EIP) displays both the NORMAL and MAINTENANCE settings for long time, long time delay, short time, short time delay, instantaneous, ground fault, and ground fault delay protective functions in the electronic trip units of typical low voltage breakers.

[0024] The foregoing summary has outlined some features consistent with the present invention in order that the enclosed herein description thereof may be better understood, and in order that the present contribution to the art may be better appreciated. The present invention is not limited in its application, details, or components merely to those set forth in the following description and illustrations. Devices consistent with the present invention are capable of other embodiments. Also, the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting unless explicitly stated as such.

[0025] Those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as a basis for designing of other structures, methods, and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the devices consistent with the present invention.

DESCRIPTION OF THE DRAWINGS AND PICTURES

[0026] FIG. 1 is a picture demonstrating the key hazards which can occur during the two second duration of an arc flash incident.

[0027] FIG. 2 is a graph illustrating the reduction of arc flash energy by the present invention.

[0028] FIG. 3 are perspective views of a first embodiment of the Maintenance Interface part of the ABC System (MIP) (Exterior View of the Front Door and Interior View of the Cabinet.)

[0029] FIG. 4 are perspective views of a first embodiment of the Main PLC part of the ABC System (MPP) (Exterior View of the Front Door and Interior View of the Front Door).

[0030] FIG. 5 are perspective views of a first embodiment of the Electrical Equipment Interface part of the ABC System (EIP) (Interior View of the Front Door and Exterior View of the Front Door.)