Gas cooled solid conductor series loop cap assembly

Details Gas cooled solid conductor series loop cap assembly Gas cooled solid conductor series loop cap assembly

1999-11-10

2001-05-15

Ramirez, Nestor (Department: 2834)

Electrical generator or motor structure

Dynamoelectric

Rotary

C029S592100

Reexamination Certificate

active

06232682

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to a cap for insulating series loop connections on bar wound armatures of electrical systems such as generators and, more particularly, to a cap assembly for providing series loop cooling and extended electrical creepage distances from loop to loop.
U.S. Pat. No. 5,633,543 and U.S. Pat. No. 5,652,469 describe ventilated cooling systems for rotating electrical machines, such as generators, which provide for end region cooling.
An exemplary reverse flow ventilation system of the type disclosed in U.S. Pat. No. 5,633,543, is illustrated by way of example in FIG.
1
. More specifically,
FIG. 1
shows a cross-section of one-half of a generator
10
(see axial center-line
12
and longitudinal center-line
14
) having a conventional reverse flow ventilated cooling system. A portion
16
of the flow of cooling gases is directed to the rotor
18
. The cooling gases are drawn through ventilation ducts
20
in the rotor by centrifugal forces created by the spinning rotor. As the gases flow through the rotor, heat in the rotor is transferred to the gases. The heated rotor gases exit the ducts
20
at the surface of the rotor into an air gap
22
between the rotor
18
and stator
24
. Spinning fans
26
mounted at the ends of the rotor draw the heated gas through the gap
22
between the stator and rotor. The heated gas is directed by an external duct
28
to a heat exchanger
30
that cools the gas.
The stator
24
is cooled by ventilation flow paths that are separate from the flow path in the rotor. Cold gas
32
cooled by the heat exchanger
30
enters a plenum chamber
34
surrounding the stator
24
. Because the end sections of the stator are closest to the rotor exhaust fans
26
, cooling gas tends naturally to flow in greater volume near the ends of the stator than through ducts at the center of the stator. This potential unbalance in the flow of cooling gas through the stator has traditionally been compensated for by baffle chambers
36
that extend around outer surface
38
of the stator.
The cooled gas
32
passes through the baffle chambers
36
(or directly to the stator near the center of the stator) and into cooling gas intake ducts
40
defined between packets
42
of stator core laminations. As the gas flows radially inward through the stator, heat from the stator coils
44
,
46
is transferred to the gas. The fans
26
draw the warmed gas from the stator, into the air gap
22
and out to the external duct
28
to the heat exchanger
30
.
A portion of the cooled gas
32
from the heat exchanger
30
is exhausted from exhaust ports
48
in the ends of the plenum chamber
34
and flows around the stator to cool the stator end turns
50
.
U.S. Pat. No. 5,142,182 describes an adjustable width cap for insulating the series loop on wound armatures in electrical systems. The molded cap is formed from two identical cap sections which are assembled to define a loop cap enclosure that is adjustable in width for receiving different sized series loops. To mechanically lock the cap sections to one another, potting resin is disposed within the cap section.
The provision of molded end caps as disclosed in U.S. Pat. No. 5,142,182 precludes the direct gas cooling of the solid series loops
50
. Thus, heat generated thereby must be thermally conducted along a heat flow path from the electrical winding, through the molded cap to the cooling gas.
BRIEF SUMMARY OF THE INVENTION
The present invention is embodied in a modified cap assembly for providing ventilation to solid series loops, which concurrently extends electrical creepage distances from loop to loop. In an embodiment of the invention, the solid series loops are ventilated by providing ventilation openings in the side walls of the cap and a cooling gas flow path through the cap to allow forced convective cooling of the conductor and, thus, the electrical winding therewithin. More specifically, the invention is embodied in a cap for disposition on a series loop of a bar wound armature of an electrical system, that is formed by assembling a pair of cap sections. A cutout is defined in one or both side walls of one or both cap sections to provide at least one ventilation opening in each side wall of the assembled cap. In the presently preferred embodiment, the conductor bars of the series loop disposed within the cap are configured to define gas flow passage(s) between the ventilation openings.


REFERENCES:
patent: 2929943 (1960-03-01), Richardson et al.
patent: 3010038 (1961-11-01), Manni
patent: 3075250 (1963-01-01), Strohm
patent: 3151260 (1964-09-01), MacCracken et al.
patent: 3648091 (1972-03-01), Kostin et al.
patent: 3978359 (1976-08-01), Kultzow et al.
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patent: 5093598 (1992-03-01), Fort
patent: 5142182 (1992-08-01), Grant
patent: 5633543 (1997-05-01), Jarczynski
patent: 5652469 (1997-07-01), Boardman et al.
patent: 5866960 (1999-02-01), Meier et al.
patent: 5883448 (1999-03-01), Zimmerman

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