Leakage current detection in cable tray

Abstract

The present invention is entitled "Leakage Current Detection in Cable Tray." The present invention provides a leakage detector for use with a cable tray raceway configured to support one or more electrical cables. The leakage detector includes an electrical conductor extending generally transverse to a length of the cable tray raceway around the cable tray raceway. A magnetic sensor is coupled to the electrical conductor. In use, the leakage detector is configured to sense a magnetic flux generated by current flowing through one or more electrical conductors adjacent to the leakage detector. More than one leakage detector can be used in a leakage detection system. The leakage detection system can also include a central computing device to determine whether a leakage current is present from the one or more electrical conductors in the cable tray raceway based on signals received from the leakage detector.

Description

[0001] Citation of relevant applications

[0002] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 157,084, filed March 5, 2021, the contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates in its entirety to a leakage current detection system for cable trays. Background Technology

[0004] Wires (cables) are guided from one end to the other through cable trays. Currently, if any wire damage occurs (e.g., insulation wear), current leaks through the cable trays. Typically, cables are bundled and run through the trays. Furthermore, these cable trays are installed at a certain height above the ground, making it challenging to physically detect wire damage. Summary of the Invention

[0005] In one aspect, a cable tray assembly typically includes a cable tray trough of a certain length. The cable tray trough is configured to support one or more electrical conductors. A first leakage detector is disposed at a first longitudinal position within the cable tray trough. The first leakage detector includes a first magnetic sensor. In use, the first leakage detector is configured to sense the magnetic flux generated by a current flowing through one or more electrical conductors adjacent to the first leakage detector. A second leakage detector is disposed at a second longitudinal position within the cable tray trough. The second leakage detector includes a second magnetic sensor. In use, the second leakage detector is configured to sense the magnetic flux generated by a current flowing through one or more electrical conductors adjacent to the second leakage detector. The first and second longitudinal positions are spaced apart from each other along the length of the cable tray.

[0006] On the other hand, a leakage detection system used with a cable tray duct configured to support one or more cables typically includes a first leakage detector configured to be positioned at a first longitudinal location within the cable tray duct. The first leakage detector includes a first magnetic sensor. In use, the first leakage detector is configured to sense the magnetic flux generated by a current flowing through one or more electrical conductors adjacent to the first leakage detector. A second leakage detector is configured to be positioned at a second longitudinal location within the cable tray duct. The second leakage detector includes a second magnetic sensor. In use, the second leakage detector is configured to sense the magnetic flux generated by a current flowing through one or more electrical conductors adjacent to the second leakage detector. A central computing device is configured to receive: i) a first signal from the first leakage detector indicating the magnetic flux generated by the current flowing through one or more electrical conductors adjacent to the first leakage detector, and ii) a second signal from the second leakage detector indicating the magnetic flux generated by the current flowing through one or more electrical conductors adjacent to the second leakage detector. The central computing device is configured to compare the first signal and the second signal to determine whether leakage current exists from one or more electrical conductors in the cable tray duct.

[0007] On the other hand, leakage detectors used with cable trays configured to support one or more cables typically include an electrical conductor configured to extend generally transversely to the length of the cable tray. A magnetic sensor is coupled to the electrical conductor. In use, a second leakage detector is configured to sense the magnetic flux generated by the current flowing through one or more electrical conductors adjacent to the leakage detector.

[0008] Other purposes and features will be apparent in part and are indicated in part herein. Attached Figure Description

[0009] Figure 1 This is a schematic diagram of a cable tray assembly that includes a leakage current detection system.

[0010] Figure 2 This is a perspective view of a cable tray assembly including a leakage detector for a leakage current detection system.

[0011] Figure 3 This is a schematic diagram of a leak detector including a Hall effect sensor for use in a 6" wide cable tray.

[0012] Figure 4 This is a schematic diagram of a leak detector including a Hall effect sensor for use in a 36" wide cable tray.

[0013] Figure 5 This is a magnified schematic detail of the leak detector. Detailed Implementation

[0014] Electrical distribution systems in factories, residential buildings, and other applications typically utilize cable trays to carry overhead cables and wall wiring. Cable trays are also known as cable conduits or cable ducts. For example, due to environmental factors or overheating, cable insulation may weaken, allowing current to leak through the metal cable tray. Leaks can occur anywhere in the cable system, and cable trays are often installed at a certain height above the ground, making physical detection of cable damage challenging. Locating the location of a leak is crucial for de-energizing specific areas for maintenance and for avoiding system-wide power outages. Accurate leak location leads to faster repairs and reduces the manual labor required to identify the leak.

[0015] Generally speaking, this disclosure relates to a leakage current detection system configured to help identify the location of leakage current along cable trays. This leakage current detection system makes the cable tray "smart," allowing it to identify the location of damaged cables and transmit that location to the operator / technician.

[0016] See Figure 1 A cable tray assembly constructed in accordance with the teachings of this disclosure is generally shown at reference numeral 208. As described below, the cable tray assembly 208 includes a cable tray 210 (or cable tray duct) and a leakage current detection system, generally shown at 214, configured to detect leakage current emanating from one or more cables 216 (or other electrical conductors) within the cable tray and transmit it to an operator / technician. The cable tray 210 can be a conventional cable tray, such as, but not limited to, basket-type or ladder-type cable trays. The leakage current detection system 214 can be retrofitted onto an existing cable tray duct 210 after installation, or the leakage detection components can be mounted on the cable tray prior to installation.

[0017] See Figure 1 and Figure 2 The leakage detection system 214 shown includes two (or more) leakage detectors, generally shown at 220A and 220B respectively, spaced apart from each other along the length of the cable tray 210 in the direction of current flowing through the cable 216 supported by the cable tray trough. It should be understood that the leakage detection system 214 may include any number of leakage detectors 220A and 220B, and it is anticipated that the system will include a large number of leakage detectors in most cases. Except for their location on the cable tray trough 210, the leakage detectors 220A and 220B may be identical, and therefore, identical components are indicated by the same reference numerals in the figures. Each of the leakage detectors 220A and 220B includes an electrical conductor 225 (e.g., an insulated electrical conductor, such as insulated wire) and a magnetic sensor 230 coupled to the electrical conductor and configured to detect a magnetic field. Figure 2 As shown, the electrical conductor 225 may extend around the cable tray 210, such as in a loop, and has a length that extends generally transversely to the length of the cable tray trough 210. Figure 3 and Figure 4 As shown, the length or size of the loop of the electrical conductor 225 may depend on the size of the cable tray 210. For example, Figure 3 A leak detector for a 6" wide cable tray is shown, while Figure 4 A leak detector for a 36" wide cable tray is shown. Other suitable sizes are envisioned.

[0018] See Figure 1 The magnetic sensor 230 shown includes a Hall effect sensor or Hall sensor 250. This sensor 250 operates based on the Hall effect principle known to those skilled in the art. When a conductor or semiconductor with current flow is introduced perpendicular to a magnetic field, voltage can be measured relative to the current path at a right angle. The Hall effect sensor 250 provides a proportional voltage to the magnetic flux density applied to the sensor. Figure 1 As shown and described below, the magnetic sensor 230 may include other electrical components to implement the leakage current detection system 214 and communicate with the central computing device 260. Other types of sensors besides Hall effect sensors can be used with the magnetic sensor.

[0019] See Figure 1 To best understand the operation of the leakage current detection system 214 during use. For example... Figure 1 As shown, cable 216 is supported by and within cable tray trough 210. Two of the leakage detectors 220A and 220B are coupled to the cable tray and spaced apart along the length of the cable tray trough. One of the leakage detectors is considered an incoming or upstream leakage detector 220A because it detects an incoming current I1 flowing into the longitudinal space between the leakage detectors, and the other leakage detector is considered an outgoing or downstream leakage detector 220B because it detects an outgoing current I2 flowing out of the longitudinal space between the leakage detectors.

[0020] An incoming current I1 at the leakage detector 220A generates a first magnetic flux, which is concentrated by the insulated iron wire 225 of the leakage detector 220A. The flux is limited using the first insulated iron wire 225 surrounding the cable tray 210. A Hall effect sensor 250 at the leakage detector 220A senses a parameter (e.g., magnitude) of the effective magnetic flux. Specifically, the Hall effect sensor 220A generates a voltage corresponding to the effective magnetic flux. This signal or detection is transmitted, for example, to a central computing device 260 via a wireless or wired connection. In one example, the voltage signal from the Hall effect sensor 250 is amplified and converted into a first DC current via a voltage amplifier and rectifier 270. If the cable 216 carries AC current, the signal from the Hall effect sensor 250 will also be an AC current. The converted DC signal is passed through an RC circuit 280 for stabilization. The stabilized signal from the RC circuit is converted into a digital signal by an analog-to-digital converter (ADC) 280. For example, the digital signal is transmitted to the central computing device 260 via a wireless transmitter 290 (e.g., a wireless transceiver).

[0021] Similarly, the outgoing current I2 at the outgoing leakage detector 220B generates a second magnetic flux, which is concentrated by the insulated iron wire 225 of the outgoing leakage detector. The flux is limited using the insulated iron wire 225 surrounding the cable tray 210 of the outgoing leakage detector 220B. The Hall effect sensor 250 of the outgoing leakage detector 220B senses a parameter (e.g., magnitude) of the effective magnetic flux. Specifically, the Hall effect sensor 220A generates a voltage corresponding to the effective magnetic flux. In general, this signal or detection is transmitted to a central computing device 260 via a wireless or wired connection. In one example, the voltage signal from the Hall effect sensor 250 is amplified and converted into a DC current via a voltage amplifier and rectifier 270. If the cable 216 carries AC current, the signal from the Hall effect sensor 250 will also be an AC current. The converted DC signal is passed through an RC circuit 280 for stabilization. The stabilized signal from the RC circuit is converted into a digital signal by an analog-to-digital converter (ADC) 280. For example, the digital signal is transmitted to the central computing device 260 via a wireless transmitter 290 (e.g., a wireless transceiver). Generally, the structure and operation of the first leak detection sensor 220A and the second leak detection sensor 220B can be identical.

[0022] Central computing device 260 includes readable storage and a processor for executing instructions stored in the readable storage. Computing device 260 receives digital signals from incoming leakage detector 220A and outgoing leakage detector 220B, respectively, and may receive signals from other leakage detectors where applicable. For example, central computing device 260 may include a wireless receiver 295 (e.g., a wireless transceiver) for receiving wireless signals from leakage sensors 220A, 220B. Suitable communication protocols include LoRA, Zigbee, or BLE protocols. The processor of computing device 260 compares the received signals to determine whether there is current leakage in portions of one or more cables 216 disposed between the two leakage detectors 220A, 220B. If the incoming current I1 equals the outgoing current I2, the digital signals will be substantially equal, indicating that there is no current leakage between the first leakage detector 220A and the second leakage detector 220B. If the incoming current I1 is not equal to the outgoing current I2, the first received signal and the second received signal will be unequal, indicating the presence of a leakage current I3 in a specific cable tray 210 between the identified first detection sensor 220A and the second detection sensor 220B. If the leakage current I3 is detected based on signals from the first leakage detector 220A and the second leakage detector 220B, the central computing device 260 can generate an alarm signal (e.g., a visual and / or audible alarm 300) to indicate the presence of the leakage current I3 to a technician. The computing device 260 can be configured to provide information to the operator / technician, including the location of the leak and other information related to the leak.

[0023] The described leakage current detection system is applicable to both AC and DC currents, and is independent of the current direction, but depends on the magnitude of the current entering the cable in the longitudinal section between the incoming and outgoing leakage detectors. Leakage detectors 220A and 220B can be integrated with batteries and wireless systems for monitoring. Accuracy can be increased by placing multiple leakage detectors at spaced intervals along the cable tray runner.

Claims

1. A cable tray assembly with a leakage detection system, the cable tray assembly comprising: A cable tray has a base, opposing sidewalls extending from the base, and a certain length, wherein the cable tray is configured to support one or more cables. A first leakage detector is configured to be disposed at a first longitudinal position in the cable tray trough. The first leakage detector includes a first magnetic sensor and a first electrical conductor coupled to the first magnetic sensor. In use, the first leakage detector is configured to sense magnetic flux generated by current flowing through one or more cables adjacent to the first leakage detector. The first electrical conductor extends around the cable tray trough in a direction generally transverse to the length of the cable tray trough. A second leakage detector is configured to be disposed at a second longitudinal position in the cable tray trough. The second leakage detector includes a second magnetic sensor and a second electrical conductor coupled to the second magnetic sensor. In use, the second leakage detector is configured to sense magnetic flux generated by current flowing through one or more cables adjacent to the second leakage detector. The second electrical conductor extends around the cable tray trough in a direction generally transverse to the length of the cable tray trough. and A central computing device configured to receive: i) a first signal from a first leakage detector, the first signal indicating the magnetic flux generated by current flowing through one or more cables adjacent to the first leakage detector, and ii) a second signal from a second leakage detector, the second signal indicating the magnetic flux generated by current flowing through one or more cables adjacent to the second leakage detector, wherein the central computing device is configured to compare the first signal and the second signal to determine whether there is leakage current from one or more cables in the cable tray.

2. The cable tray assembly of claim 1, wherein the central computing device is configured to determine the presence of leakage current if the magnetic flux indicated by the first signal and the magnetic flux indicated by the second signal are not substantially equal to each other.

3. The cable tray assembly of claim 1, wherein the leakage detection system further includes an alarm communicating with the central computing device, wherein the central computing device is configured to activate the alarm if the central computing device determines that there is leakage current from one or more cables in the cable tray trough.

4. The cable tray assembly of claim 1, wherein the first leak detector and the second leak detector communicate wirelessly with the central computing device.

5. The cable tray assembly of claim 1, wherein each of the first magnetic sensor and the second magnetic sensor comprises a Hall effect sensor.

6. The cable tray assembly of claim 1, wherein each of the first electrical conductor and the second electrical conductor extends in a loop around the cable tray routing channel.

7. The cable tray assembly of claim 6, wherein the longitudinal ends of the first electrical conductor and the second electrical conductor are coupled to corresponding magnetic sensors in the first magnetic sensor and the second magnetic sensor.

8. The cable tray assembly of claim 6, wherein each of the first electrical conductor and the second electrical conductor comprises an insulated electrical conductor.

9. The cable tray assembly of claim 1, wherein the first leak detector and the second leak detector communicate with the central computing device via wired or wireless communication.

10. The cable tray assembly of claim 1, wherein the first leak detector and the second leak detector are battery powered.

11. The cable tray assembly of claim 1, further comprising a third leakage detector disposed at a third longitudinal position in the cable tray trough, the third leakage detector comprising a third magnetic sensor, wherein in use, the third leakage detector is configured to sense the magnetic flux generated by the current flowing through the one or more cables adjacent to the third leakage detector. The third longitudinal position is spaced apart from the first longitudinal position and the second longitudinal position along the length of the cable tray.

12. The cable tray assembly of claim 1, further comprising the one or more cables received in the cable tray trough.

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