Information
-
Patent Grant
-
6676447
-
Patent Number
6,676,447
-
Date Filed
Thursday, July 18, 200222 years ago
-
Date Issued
Tuesday, January 13, 200420 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
- Bracewell & Patterson, LLP
-
CPC
-
US Classifications
Field of Search
US
- 439 587
- 439 588
- 439 589
- 439 274
- 439 275
- 439 278
- 439 271
-
International Classifications
-
Abstract
A pothead connector for an electrical submersible pump motor includes a housing. A first insulating block is disposed within the housing and has passages for receiving insulated conductors of the power cable. The passages in the first insulating block have counterbores on an second end. A second insulating block is also disposed within the housing. The second insulating block has passages through which the insulated conductors pass. The second insulating block also has protrusions on a first face that are concentric with the counterbores and shaped to fit within the counterbores in the first insulating block. An elastomeric washer is positioned within each of the counterbores. A fastener rigidly secures the second insulating block to the first insulating block, forcing the protrusions against the elastomeric washers to cause the washers to seal around the insulated conductors.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to downhole electrical connectors for use in oil field applications. More specifically, the present invention relates to a pothead connector for connecting an insulted power cable to the motor of an electric submersible pump.
2. Description of the Related Art
Downhole electric submersible pumps are driven by electric motors. The electric motor is powered from the surface, so a cable must be fed down the well to the pump motor. Prior to lowering the motor, a motor lead of the cable is attached with what is known in the art as a pothead connector. The pothead connector secures the motor lead to the motor so that it is not loosened as it is lowered. The pothead connector must also be able to withstand the downhole environment, which may include caustic materials under high pressure and temperatures. The service life of the pothead connector depends on its ability to seal effectively.
Various sealing techniques and cable securing means have been used. Typically, a metal housing is used for the connector. An insulating block mounts inside the housing. The insulating block has passages for receiving the insulated conductors. Electrical contact pins are secured to each conductor and protrude from the forward side of the insulating block. Epoxy is filled in the spaces around the conductors within the housing to seal the conductors and secure them. The housing has an integral cylindrical lip that protrudes past the insulating block for reception in a mating receptacle.
SUMMARY OF THE INVENTION
In accordance with the present invention, a pothead connector is provided with a protective housing near the terminal end of a motor lead. In all of the embodiments, an insulating block is mounted in the housing. The insulating block has at least one hole therethrough for receiving an insulated electrical conductor. An electrical contact pin is secured to the conductor within the insulating block and protrudes from the insulating block. A cylindrical wall or lip is integrally formed on the insulating block and protrudes past a first end of the housing. A seal is located on the outer diameter of the lip.
In another embodiment, the insulating block has a counterbore in a second end. A second insulating block is also disposed within the protective housing. The second insulating block has a passage through which the insulated conductor passes. The second insulating block also has a protrusion on a lower face that is concentric with the counterbore and shaped to fit within the counterbore in the first-mentioned insulating block.
An elastomeric washer is positioned within the counterbore at the second end of the passage in the first insulating block. The elastomeric washer has a hole through which the insulated conductor passes. A fastener rigidly secures the second insulating block to the first insulating block, forcing the protrusion against the elastomeric washer to cause the washer to seal around the insulated conductor. The elastomeric washer will also effectively secure the insulated conductor in the protective housing.
The fastener may take the form of a shoulder engaging the second end of the second insulating block coupled with a retaining ring engaging the first insulating block. Alternatively the fastener may be a threaded connector between the two insulating blocks. A threaded connector could include a spring to compensate for thermal expansion.
In still another embodiment, the insulating block is formed of a thermoplastic material that is compatible with a thermoplastic insulating layer on the conductors. After installation in the holes, the insulating layer is heat fused to the insulating block.
DESCRIPTION OF THE DRAWINGS
FIG. 1
is a sectional view of a pothead connector of the present invention.
FIG. 2
is a sectional view of an alternative embodiment of the pothead connector of the present invention.
FIG. 3
is a sectional view of a second alternative embodiment of the pothead connector of the present invention.
FIG. 4
is a sectional view of a third alternative embodiment of the pothead connector of the present invention.
While the invention will be described in connection with the preferred embodiments, it will be understood that it is not intended to limit the invention to those embodiments. On the contrary, it is intended to cover all alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.
DESCRIPTION OF THE INVENTION
Referring to
FIG. 1
, electrical connector
11
has a housing
13
that is typically metal. Housing
13
is configured to be secured to an end of a motor lead portion of a power cable
15
of a downhole electrical submersible motor (not shown). Motor lead
15
has three electrical conductors (only two shown) in the preferred embodiment. Each conductor
17
has one or more layers of electrical insulation
19
. Conductors
17
extend into housing
13
through a passage in a second or upper end.
Housing
13
has an internal shoulder
21
near its first or lower end that faces in the first direction, which is to the left, as shown in the drawings. A first insulating block
23
locates within housing
13
at the first end. First insulating block
23
has an outer diameter that is the same as the inner diameter of housing
13
at shoulder
21
. The second end of first insulating block
23
abuts shoulder
21
. Block
23
is formed of a rigid electrical insulating material.
First insulating block
23
has a plurality of passages
25
(only one shown), each passage
25
receiving one of the insulated conductors
17
. Passage
25
has a counterbore
27
located on the second end of insulating block
23
. In the preferred embodiment, each counterbore
27
has a conical portion leading to a short cylindrical portion that joins the second end of first insulating block
23
. Counterbores
27
could be of different configurations, even completely cylindrical. The remaining portion of each passage
25
closely receives one of the insulating conductors
17
.
An electrical contact pin
29
is secured to the first end of conductor
17
. Pin
29
may be secured by soldering or crimping to conductor
17
. Pin
29
in this embodiment is shown to be hollow for receiving a mating pin in the submersible pump motor (not shown), but it could also be a solid male pin.
First insulating block
23
has a thin, cylindrical lip
31
integrally formed on it that protrudes forward past the first end of housing
13
. Lip
31
is formed of the same dielectric material as insulating block
23
. Lip
31
terminates short of the ends of pins
29
and is configured for reception within a mating receptacle of the pump motor. A seal
32
is located on lip
31
for sealing within the mating receptacle of the pump motor. Seal
32
is shown to be a flat elastomeric member, but it could also be an o-ring. Seal
32
is much softer than lip
31
, although both are formed of dielectric materials. Lip
31
has a smaller outer diameter than the first end of housing
13
.
An elastomeric washer
33
is located in counterbore
27
. Washer
33
is formed of a deformable electrical insulation material. Washer
33
has a central hole that closely receives insulated conductor
17
. Washer
33
has a configuration the same as the conical portion of counterbore
27
. The larger diameter or base of washer
33
is located on the second end within the cylindrical portion of counterbore
27
.
A plurality of threaded receptacles
35
(only one shown) are mounted in first insulating block
23
. Receptacles
35
are bonded to the first insulating block
23
and have open ends that face the second direction. Receptacles
35
have second ends that are substantially flush with the second end insulating block
23
.
A second or upper insulating block
37
formed of a rigid insulating material is also disposed in housing
13
. Second insulating block
37
is also generally a cylindrical disc, but in the embodiment of
FIGS. 1 and 2
, has an outer diameter that is smaller than the outer diameter of first insulating block
23
. The outer diameter of second insulating block
37
is spaced radially inward from the interior surface of housing
13
in the first and second embodiments. Second insulating block
37
also has three passages
39
, each of the passages
39
registering with one of the passages
25
of first insulating block
23
. Passages
39
in second insulating block
37
have the same diameters as passages
25
in first insulating block
23
. One of the insulated conductors
17
passes through each passage
39
.
A cylindrical protrusion
41
is formed on the first end of second insulating block
37
around each of the passages
39
. Each protrusion
41
protrudes a distance slightly less than the cylindrical portion of counterbore
27
. The outer diameter of protrusion
41
is slightly less than the inner diameter of the cylindrical portion of each counterbore
27
. Each protrusion
41
thus fits within the counterbores
27
in contact with the base of one of the washers
33
.
A plurality of fasteners
43
(only one shown) clamp insulating block
37
tightly to first insulating block
23
. Fasteners
43
are screws or bolts, each having a head and a threaded portion. Each fastener
43
extends through a hole
45
in second insulating block
37
and threads into one of the threaded receptacles
35
. Then fasteners
43
secure the first face of second insulating block
37
in tight contact with the second face of first insulating block
23
. Each protrusion
41
deforms washer
33
into tight sealing engagement with insulation layer
19
of each insulated conductor
17
. This tight engagement also secures each conductor
17
against movement relative to second insulating block
37
. After full make up, the first end of each protrusion
41
is spaced slightly from the conical portion of counterbore
27
. Epoxy
47
is pumped into the interior of housing
13
to fill all of the spaces surrounding insulated connectors
19
. After curing epoxy
47
becomes a rigid dielectric material.
Electrical conductor connector
11
is constructed by inserting insulated conductors
17
from motor lead
15
into housing
13
. Second insulating block
37
slides over the insulated conductors
17
. Washers
33
are placed in counterbores
27
, and first insulating block
23
then slides over insulating conductors
17
. Pins
29
are formed on the extreme ends of conductor
17
. Fasteners
43
are tightened to clamp second insulating block
37
tightly to first insulating block
23
. The two insulating blocks
23
,
37
are then inserted into the first end of the housing
13
until the second end of first insulating block
23
abuts shoulder
21
. The interior is filled with epoxy
47
, which rigidly bonds the components within housing
13
.
The embodiment of
FIG. 2
has many similarities, and the common features will not be discussed again. The principal difference is a provision that allows thermal expansion of each washer
133
. In this embodiment, threaded receptacle
135
is located within second insulating block
137
. Fasteners
143
pass through holes
145
in first insulating block
123
. The heads of fasteners
143
are thus located on the first or lower side. Each hole
145
has an enlarged counterbore on the first end for receiving a coil spring
49
. Spring
49
is compressed between the shoulder in passage
145
and the head of fastener
143
.
Should thermal expansion of washers
133
tend to force insulating blocks
23
and
137
apart from each other, springs
49
will allow a slight amount of this movement to occur. When installed, the first end of second insulating block
137
will be in abutting contact with the second end of first insulating block
123
. If thermal expansion of washers
133
causes them to expand relative to the blocks
123
,
137
, first insulating block
123
will move slightly in the first direction relative to block
137
with springs
49
deflecting or compressing during this occurrence. This will create a slight gap between insulating blocks
137
and
123
. After subsequent cooling, springs
49
will cause second insulating block
123
to again move back into the second direction until its second end contacts the first end of second insulating block
137
.
The second alternate embodiment, shown in
FIG. 3
, also has a number of common components with the other embodiments. Connector
211
has the same housing
213
as housing
13
of
FIG. 1
, except internal shoulder
221
is located farther from the first end. In this embodiment, second insulating block
237
has a second end that abuts internal shoulder
221
. The outer diameter of second insulating block
237
is the same as the outer diameter of first insulating block
223
. Blocks
223
and
237
slide into the first end of housing
213
until block
237
abuts shoulder
221
.
The fastener for maintaining protruding portion
241
in engagement with washers
233
differs from the threaded fasteners
43
and
143
of the other embodiments. In this embodiment, a retaining ring
53
locates within a groove
51
formed in housing
213
between the first end and internal shoulder
221
. Retaining ring
53
is designed to snap into a mating recess
55
formed on the outer diameter of first insulating block
223
. The operator will press first insulating block
223
tightly against second insulating block
237
, the blocks moving into housing
213
until retaining ring
53
snaps into groove
51
in housing
213
. This engagement will hold each washer
233
in a desired deformation due to protrusions
241
.
In the embodiment of
FIG. 4
, electrical connector
311
has a housing
313
as in the other embodiments. A single insulating block
323
is mounted in housing
311
. Insulating block
323
is rigid and has a thin, cylindrical lip
331
that protrudes forward past housing
311
as in the other embodiments. Insulating block
323
has a passage
325
for each of the conductors
317
. Each conductor
317
has one or more insulation layers
319
that slide closely inside passage
325
. An electrical contact pin
329
is secured to each conductor
317
and protrudes past insulating block
323
and lip
331
.
Insulating block
323
and insulation layer
319
are made of compatible thermoplastic materials. After insulation layers
319
are inserted into passages
325
, heat is applied to cause slight melting of the materials at the interface between insulation layers
319
and passages
325
of insulating block
323
. When cooled, the materials thermally fuse together. During manufacturing, conductors
317
are threaded through housing
313
and into passages
325
of block
323
while housing
313
is pushed rearward of block
323
. Then heat is applied to cause insulation layers
319
to fuse to block
323
. Then block
323
is pushed into housing
313
and epoxy
347
placed in the spaces in housing
313
around conductors
317
. Epoxy
347
rigidly secures block
323
to housing
313
. The fused insulation layers
319
seal and secure conductors
317
to block
323
. Examples of suitable thermoplastic materials for layer
319
and insulating block
323
include, but are not limited to the following: polyvinylchloride (PVC), polyethylene, polypropylene, fluorinated ethylene propylene (FEP), tetrafluoroethylene as a co-polymer with a fully fluorinated alkoxy (PFA), or perfluoromethylvinylether as a co-polymer with tetraflourofluoroethylene (MFA). These thermoplastics are known insulation materials for electrical power cable for downhole centrifugal pumps. Also, it is not necessary that insulating block
323
and insulation layer
319
be the same material, only that they are sufficiently compatible to thermally fuse together.
The invention has significant advantages. The protruding cylindrical lip of the insulating block provides additional dielectric thickness over the prior art, which employed a metal housing lip surrounded by a seal. The elastomeric washer provides an effective seal formed by the two insulators. The thermal fusing of the insulation layer to the insulating block seals as well as providing rigidity.
It is to be understood that the invention is not limited to the exact details of the construction, operation, exact materials or embodiment shown and described, as obvious modifications and equivalents will be apparent to one skilled in the art. For example, all of the embodiments show the conical counterbore located in the first insulating block. It should be apparent that the counterbore could alternately be located in the second insulating block. In that instance, the protrusions would be located on the second end of the first insulating block.
Claims
- 1. An electrical connector for a cable having at least one insulated conductor, the connector comprising:a housing; a rigid insulating block of insulating material disposed within the housing and having a passage for receiving an insulated conductor of the cable; a cylindrical lip of the same insulating material as the insulating block integrally formed on an end of the insulating block and protruding past an end of the housing for insertion into a mating receptacle, the lip having an outer diameter and an inner diameter that are concentric relative to an axis of the insulating block; an electrical contact pin mounted in the insulating block and adapted to be joined to the cable, the pin protruding past the cylindrical lip for mating engagement with an electrical contact in the receptacle; and an elastomeric seal extending around an the outer diameter of the cylindrical lip for sealing in the mating receptacle.
- 2. The connector of claim 1, wherein the elastomeric seal is of softer material than the cylindrical lip.
- 3. The connector of claim 1, wherein the outer diameter of the cylindrical lip is smaller than the end of the insulating block.
- 4. An electrical connector for a cable having at least one insulated conductor, the connector comprising:a housing; a rigid insulating block of insulating material disposed within the housing and having a passage for receiving an insulated conductor of the cable; a cylindrical lip of the same insulating material as the insulating block integrally formed on a first end of the insulating block and protruding past an end of the housing for insertion into a mating receptacle; an electrical contact pin mounted in the insulating block and adapted to be joined to the cable, the pin protruding past the cylindrical lip for mating engagement with an electrical contact in the receptacle; an elastomeric seal extending around an outer diameter of the cylindrical lip for sealing in the mating receptacle; a second insulating block disposed within the housing, the second insulating block having a passage for receiving the insulated conductor, the second insulating block having a first end that faces a second end of said first mentioned insulating block; a counterbore in one of the passages of one of the insulating blocks; a protrusion on the other insulating block that is concentric with and locates within at least a portion of the counterbore; a washer formed of deformable dielectric material and positioned within the counterbore, the washer having a hole for receiving the insulated conductor; and a fastener that secures the second insulating block to said first mentioned insulating block, forcing the protrusion against the washer to cause the washer to seal around the insulated conductor.
- 5. The electrical connector of claim 4, wherein:the fastener comprises a threaded connector extending between the second insulating block and the first mentioned insulating block.
- 6. An electrical connector for a cable having at least one insulated conductor, the connector comprising:a housing; a first insulating block disposed within the housing and having first and second ends, the first insulating block having a passage for receiving an insulated conductor of the cable; an electrical contact pin mounted in and protruding from the first end of the first insulating block, the contact pin adapted to be joined to the conductor of the cable; a second insulating block disposed within the housing, the second insulating block having a passage for receiving the insulated conductor, the second insulating block having a first end that faces the second end of the first insulating block; a counterbore in one of the passages of one of the insulating blocks; a protrusion on the other insulating block that is concentric with and locates within at least a portion of the counterbore; a washer formed of deformable dielectric material and positioned within the counterbore, the washer having a hole for receiving the insulated conductor; and a fastener that secures the second insulating block to the first insulating block, forcing the protrusion against the washer to cause the washer to seal around the insulated conductor.
- 7. The electrical connector of claim 6, wherein:the housing has a shoulder on an interior surface; and the second insulating block engages the shoulder and is retained against the shoulder by the fastener.
- 8. The electrical connector of claim 6, wherein:the fastener comprises a threaded connector extending between the second insulating block and the first insulating block.
- 9. The electrical connector of claim 6, wherein:the washer is conical with a base contacted by the protrusion.
- 10. The electrical connector of claim 6, further comprising a cylindrical lip integrally formed on a the first end of the first block and protruding past a first end of the housing; anda seal located on an outer diameter of the cylindrical lip.
- 11. The electrical connector of claim 8, wherein:the threaded connector passes through the second insulating block into a threaded receptacle in the first insulating block.
- 12. The electrical connector of claim 8, wherein:the threaded connector passes through the first insulating block into a threaded receptacle in the second insulating block.
- 13. An electrical connector for a cable having a plurality of insulated conductors, comprising:a housing; a first insulating block disposed within the housing, the first insulating block having a plurality of passages, each for receiving an insulated conductor of the cable, each of the passages having a counterbore; a plurality of electrical conductor pins adapted to be joined to the conductors, each of the conductor pins mounted in the first insulating block and protruding therefrom; a second insulating block disposed within the housing, the second insulating block having a plurality of passages, each for receiving one of the insulated conductors, the second insulating block having a plurality of protrusions, each of which is concentric with and located within one of the counterbores in the first insulating block; a washer of deformable electrical insulation material positioned within each of the counterbores, each washer having a hole for receiving one of the insulated conductors; and a threaded fastener extending between the second insulating block and the first insulating block, securing the second insulating block to the first insulating block and pushing the protrusions on the second insulating block into the washers in the counterbores to deform the washers into sealing engagement with the insulated conductors.
- 14. The electrical connector of claim 13, wherein:the threaded fastener extends through the second insulating block into a threaded receptacle in the first insulating block.
- 15. The electrical connector of claim 13, wherein:the housing has a shoulder on an interior surface; the first insulating block abuts the shoulder; and the second insulating block has a smaller outer diameter than the first insulating block, the outer diameter of the second insulating block being spaced inward from the interior surface of the housing.
- 16. The electrical connector of claim 13, wherein:the washers are conical, each having a base that is contacted by one of the protrusions of the second insulating block.
- 17. The electrical connector of claim 13, wherein:the first insulating block has a thin, cylindrical lip integrally formed thereon that extends beyond a first end of the housing; and a seal is located on an outer diameter of the cylindrical lip.
US Referenced Citations (13)
Foreign Referenced Citations (2)
Number |
Date |
Country |
0660447 |
Jun 1995 |
EP |
0660447 |
Jun 1995 |
EP |