The present invention relates generally to the connection of power and signal/control cables to a drive motor and, in particular, to a method and apparatus for connecting power/control cables to a submersible pump.
Submersible pumps are used for a wide variety of applications. In order to power and monitor a submersible pump, one or more electrical cables must be attached mechanically and electrically to the pump housing. Although an apparatus for making the connection currently exists, there is a need for a connection apparatus and method with improved reliability, including improved sealing to further inhibit the entry of water or other liquid into the motor housing.
The present invention provides a new and improved method and apparatus for coupling power and control/signal cables to a submersible pump housing. This disclosed apparatus and method includes multiple sealing components which further inhibit the entry of water from the operating environment, into the motor housing, even if a cable or cables are cut or otherwise mechanically fail.
According to the invention, the electrical terminal assembly is used to connect an electrical cable having multiple conductors to a submersible pump. According to the invention, the terminal housing assembly may be used to connect a power cable to the motor of a submersible pump and/or to connect a control or signal cable to corresponding components such as sensors, also located within the submersible pump housing.
The electrical terminal assembly includes a terminal housing that defines at least one bore. A first sealing element receives the overall electrical cable and includes an element bore that is engageable with an outer jacket of the electrical cable. The first sealing element is receivable and sealingly engageable with the bore defined by the housing. In a more preferred embodiment, the bore is tapered and the sealing element comprises a complementally-shaped bushing.
A gland secured to the terminal housing is operative to urge the first sealing element into sealing contact with the terminal housing bore and the outer jacket of the electrical cable, whereby fluid leakage along the outer jacket of the cable into the terminal housing is inhibited.
A second sealing element is carried by the terminal housing and includes bores for receiving the individual conductors of the electrical cable. A pressing element is operative to urge the second sealing element into sealing engagement with the terminal housing and the outside surfaces of the conductors, whereby fluid leakage into the terminal housing by way of the individual conductors is also inhibited.
The separate sealing of the outer jacket of the overall cable and the individual conductors substantially inhibits fluid leakage into the housing of the submersible pump, even if the outer jacket of the cable is damaged.
According to the illustrated embodiment, the terminal housing defines a second bore for receiving a second electrical cable and includes another set of first and second sealing elements for sealing the outer jacket of the second electrical cable and the individual conductors of the second electrical cable. In practice, one of the electrical cables typically comprises a power cable for providing power to the motor of the submersible pump, whereas the second cable is considered a signal or control cable and transmits control or sensor signals to and from the submersible pump.
In the exemplary embodiment, the pressing element for clamping the second sealing element comprises a spacer having bores that align with the bores formed in the second sealing element. In addition, both the second sealing element and the spacer include aligned bores for a clamping fastener that extends through the aligned bores and threadedly engages the terminal housing. When the fastener is tightened, the second sealing element is sealingly clamped by the spacer and sealingly engages both the terminal housing and the outside surfaces of the individual conductors.
In the preferred and illustrated embodiment, as the gland applies axial forces to the first sealing element or bushing, it co-acts with the tapered bore formed in the terminal housing to cause it to constrict radially inwardly, thus sealingly engaging the outer jacket of the associated serial cable.
According to an additional feature of the invention, the individual conductors of the electrical cable terminate in a quick disconnect connector and corresponding conductors in the submersible pump terminate in a mating quick disconnect connector, whereby the electrical cable can be easily disconnected from the submersible pump when the terminal housing is released from the housing of the submersible pump.
In the illustrated embodiment, a terminal housing assembly is disclosed in which sealing bushings are used to seal the outer jackets of both the power and control cables to the terminal housing. A pair of terminal glands secured by threaded fasteners press the bushings into sealing engagement with the terminal housing and the outer surface of the cables. The individual conductors in the control and powered cables pass through another pair of sealing bushings associated with the cables. The latter sealing bushings are sealingly clamped to the terminal housing by a unitary clamping or spacer element.
According to the preferred method for connecting a multi-conductor cable to a submersible pump, the electrical cable to be connected is passed through a sealing bushing held in a bore defined by a terminal housing. A predetermined length of an outer jacket forming part of the electrical cable is stripped back to expose individual conductors. A gland mounted to the terminal housing is used to apply forces to the sealing bushing in order to urge it into sealing contact with the terminal housing bore and the outer jacket of the electrical cable. The individual conductors are then passed through individual bores in a second sealing bushing. The second bushing is then clamped to the terminal housing using a pressing element or a spacer that urges the second sealing bushing into sealing contact with the terminal housing and the outer surfaces of each of the individual conductors. The terminal housing is then sealing attached to a pump housing forming part of the submersible pump.
To further facilitate replacement of the electrical cable when needed, the individual conductors in the cable terminate in a quick disconnect-type connector and the corresponding conductors in the submersible pump are terminated in a mating quick disconnect connector. With the disclosed invention, replacement of the cable involves removal or release of the terminal housing from a submersible pump (after the pump is removed from its operating environment) and the quick disconnect connector portions are separated, thus facilitating replacement of a damaged or failed electrical cable with a replacement cable having the terminal housing already attached.
With the disclosed invention, a first seal is used to seal the outer jacket of a cable to the housing and a second seal seals the conductors of a cable to a housing. This dual sealing arrangement further inhibits the entry of water into the pump motor housing. The disclosed terminal housing assembly also facilitates the repair or replacement of the power cable/control cable connection to the submersible pump.
Additional features of the invention will become apparent and a fuller understanding obtained by reading the following detailed description made in connection with the accompanying drawings.
Cables 18 and 19 both contain multiple conductors. Each cable has an outer jacket 21 (Shown best in
As seen in
If the cable shown in
As seen in
It is also contemplated that cables 18 and 19 could be combined into one single cable, with all of the conductors inside of one outer jacket. While this might simplify the number of parts, it would make the cable stiffer and might add additional cost to the product. There may be other advantages or disadvantages of using a single cable instead of two.
It is also conceived that in some cases a single submersible pump might require more than one complete terminal housing subassembly 20. This could be due to the amount of electrical current or the type of voltage required to operate the pump or other possible causes.
Power cable 19 is what carries the actual current required to the submersible pump motor in order to power it. Control cable 18 connects to multiple sensors within the pump to provide feedback to a conventional motor control panel (mounted above the water surface—not shown) to give indication of whether there is a fault within the unit. Any such fault would trigger the control panel to terminate sending current through the power cable 19. Some of the sensors contemplated to be connected to the control cable include moisture detection and thermal readings. Other sensors could be used in addition to these or in place of these.
The sealing arrangement for both the power cable 19 and the control cable 18 may be substantially identical other than the number of individual conductors.
Prior to assembly, the power cable 19 and the control cable 18 have their outer jackets stripped off a predetermined length from their respective ends. Each individual conductor 23, 25 is then also stripped a predetermined length from their ends (see
The next step in the assembly procedure would be to slide the terminal glands 5 (see also
Referring to
Referring to
The individual conductors 23, 25 of the power cable 19 and control cable 18 are then fed through bushings 3 (see also
The bushings 3, 4, 9, 10 are preferably made from an elastomer. Examples of elastomers that are contemplated include, but are not limited to, neoprene rubber or a fluorinated elastomer such as Dupont Viton or equivalent. It should be noted here that the spacer 2, the bushings 3, 10 and the housing 20a are shown with sets of four bores (2a, 3a, 10a, 31) equally spaced about a center bore. The number of bores spaced about the center bore may vary depending on the number of conductors in the control and power cables 18, 19. With some applications, less than four conductor bores may be needed, whereas in other application, more than four bores will be required.
Terminal housing 20a is installed onto the submersible motor housing with a nut 60 and stud 62 arrangement (shown in
Prior to installing the terminal housing to the motor housing as described above, the stripped ends of the individual conductors 23, 25 from the power cable 19 and the control cable 18 are installed into respective cable connectors 49, 48 as shown in
In the preferred and illustrated embodiment, the terminal housing 20a is constructed of cast iron. Other metal materials or non-metal materials for the terminal housing 20 are contemplated by the invention.
With the disclosed invention, the integrity and reliability of the electrical connections to a submersible pump are greatly improved. Moreover, serviceability is also improved. By providing separate seals for the overall cable and the individual conductors, leakage into the motor housing of the submersible pump is substantially inhibited. Serviceability is improved because the replacement of a damaged or failed cable can be easily accomplished by simply removing the submersible pump from its sump, releasing the terminal housing from the pump housing and then separating the connectors 48, 49. The invention contemplates providing a length of cable with one end already attached to the terminal housing and with the individual conductors attached to the connectors 48, 49. With this configuration, the replacement cable with terminal housing attached is simply coupled to the connectors 58, 59, forming part of the submersible pump, followed by attachment of the terminal housing to the submersible pump housing by means of the nuts 60 and the studs 62 (shown in
It should also be noted here that the invention contemplates, as indicated above, multiple terminal housings mounted to a given pump to accommodate multiple power and control/signal cables. Those skilled in the art will recognize that the principles of the invention can be applied to construct a terminal housing for attaching three or more electrical cables to a submersible pump
Although the invention has been described with a certain degree of particularity, it should be understood that those skilled in the art can make various changes to it without departing from the spirit or scope of the invention as hereinafter claimed.
This application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/388,915, filed on Oct. 1, 2010, the disclosure of which is entirely incorporated herein by reference.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/US11/54147 | 9/30/2011 | WO | 00 | 3/26/2013 |
Number | Date | Country | |
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61388915 | Oct 2010 | US |