Note: Descriptions are shown in the official language in which they were submitted.
2149693
GLAND PERMITTlNG LEAK TESTING
OF LEAD PEI!~ETRATIO~S
TECHNICAL ~IELD
s
This invention broadly relates to generators and more particularly to an
improved gland design which will allow lead, i.e., wire, pen~t~ation~ to be
tested for air tightn~ss prior to start-up of the generator.
BACKGROUND
GenP~tors typically include inshu~ n and other devices which
require the generator frame to admit wires ~ t~ with such devices. At
the same time, it is of critical importance to prevent hyd~o&cn gas within the
5 gcne.ator from leaking to ~tmosphP~e. One source of potential hydlogen gas
leakage is the point at which ina~ nl~l;nn and/or other wires enter/exit the
grn. ..~tor frame and thus, it is ,c~u~ to provide an cffective seal or gland
which will allow the wires to pPn-tratP the gcn. ,llo~ frame but without
pf.",;ll;n~ hy~rogcn gas to leak out along the wires.
One conventional gland construction is shown in Figure 1 where a
gland 10 is i~ str~tpd in place within the wall 12 of a genP~ator. The g!and
10, as alrcady noted, is de~ignpA to allow wires to enter/e~cit the genc~or
frame while pl~cnting hydrogen gas leakage. The gland 10 in this
25 conventional arrangement includes a subst~nti~lly cylin~nc~l steel gland body14 in~lt)~inE an outer ~iphe.~l wall 16 and radial wall 18 at one end, the
radial wall having a centrally located apc,lu~e 20. The O~pOaitc end of the
gland body 14 is provided with a plurality of threaded bolt holes 22 so that a
disk-like pressure plate 24 with aligned bolt holes 26 can be secured to the
30 body 14 via a cGl,c~nding plurality of bolts 28. The prcsaule plate 24 is
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also provided with a centrally located opening 30 of approximately the same
di-q-mete~ as (and axially aligned with) opening 20 in radial wall 18.
The gland body receives a pair of disk-like Textalite~ spacer plates 32,
s 34 on either side of a disk-shaped rubber packing gasket 36. These spacer
plates 32, 34 and the rubber gasket 36 are sized to fit within the gland body
as shown. In addition, a compressible gasket 38 of rubber or other suitable
mqt~riql is inserted between the spacer plate 32 and the radial wall 18. A
wire 40 is shown passing through the gland 10 and out of the ~ A~or wall
0 12, the wire 40 in-~lu~ing a copper strand 42 and an inclllqtin~ sleeve 44. The
wire 40 is stripped of its sleeve 44 in arus on either side of, and within, the
rubber packing 36. This arrangement, upon tight nine of the pressure plate
24, results in 360~ co"lp-ession of the packing 36 directly against and about
the metal wire strand 42 to insure gas tight sealing.
While this conventional qrrangem~nt has provided g~n~lly ~ccept~ble
sealing ~- rv~ n~e~ it is disadvantageous in that it does not permit p~,SSIIlc
rh~ing of the gland for gas tightn~cc prior to geh~ Ator start-up.
DISCLOSU~F. OF l~F INVFl~IION
This invention has for its prinrip~l ob,e.li-e an effective sealing gland
which improves the sealing properties of the gland, allows for the quick
25 ~et~ction of gas leakage, and also inco~ tes means for checl~ing gas
tightn~ss of the lead pCncL~,tions prior to generator start-up. In an eYemp
embo~im.-nt the invention essPnti~lly incGl~olAtes a pair of conventional
gland arrange."cr,t~ within a single gland body, with a center cavity between
the two glands used for detecting leakage and/or ch~inP gas tightn~s5 The
30 center cavity is ch~nn~led out of the gland through a drilled hole in the
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a~jacl~nt spacer plates and then axially through the gland body. A conduit
extends from the gland body ~o a hydrogen detection device which alerts the
operator to a hydrogen gas leak in the first or inner of the two axially alignedglands. The second or outer gland insures against leakage of the hydrogen
5 beyond the first or inner gland.
The invention also permits pL~;,a,,re testing of the gland prior to
gene.~,tor start-up.
0 The invention also permits continuous monitoring of mllltiple glands in
a manner which permits accurate detection and id~ntifi~ on of the leaking
gland.
In its broader aspects, the.~fo~c, the invention relates to a sealing gland
5 for ~,llPiuing at least one wire to p~ t~ a wall of a vcssel while preventing
leakage of a gas from the vessel, the gland comrn~ing a gland body; a pair of
seals located within the body with an air space formed b~ n the seals; at
least one wire passing through the gland, the pair of packing seals and the air
space; and a conduit comml~ni~ting the air space with a gas det~tioll device.
Other objects and advantages of the invention will become apparent
from the detailed d~c~ ion which follows.
BRIE:F DESCRI~IO~ OF T~IE DRAW~GS
FIGIJRE 1 is a side elevation, partly in section, illustrating a
cG-,~cnLional gland;
FIGURE 2 is a side elevation, partly in section, illustrating a gland in
30 accordance with this invention;
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FIGURE 3 is a partial end view of the gland illustrated in Figure 2;
FIGURE 4 is an enlarged detail A taken from Figure 2; and
FIGURE 5 is a sc~Pm~tiC diagram of a multiple gland continuous
monitoring arrangement in accordance with the invention
BEST MODE FOR CARRYING OUT ~IE INVENTION
With reference now to Figure 2, a gland 50 in acco,-lance with this
invention is shown welded in place within a gcne~ltor wall 52. The gland 50
in~ d~s a cylin~ri~l gland body which in~ludes a p~ . ;p~ ",l wall 56 and a
radial end wall 58 at the genelalor end of the gland. As in the conventional
gland, the radial end wall 58 has a centrally located opcning 60 therein to
5 permit passage of any number of wires W (one shown) through the gland.
The ~liph~l wall 56 in accG,~ncc with this invention has an axial
length greater than the conventional gland 10 decrrihed above, in order to
accommod~te a pair of packing arrange.llcn~ as des~ nhed below. The open
20 end of the gland (remote from the gcnelator) is provided with a plurality of
bolt holes 62 in a circular array (see also Figure 3).
Within the gland body are inserted the following el~ "- .t~ from left to
right: a solid disk gasket 64; a first spacer plate 66; a first packing seal 68; a
25 second spacer plate 70; a third spacer plate 72; a sccond packing seal 74; and
a fourth spacer plate 76.
The gasket 64, which may be rubber, is provided in the form of a solid
disk-like ,ne..iber formed with one or more holes for receiving one or more of
30 the wire leads W exiting the generator wall 52.
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The first and fourth spacer plates 66 and 76 are formed of a solid non-
metallic but relatively rigid material such as Textaliten' (other suitable material
may also be used), and are shaped as solid disks having a slight clearance fit
or friction fit within the gland body. The second and third spacer plates 70
5 and 72 are formed of a similar m~n~l but these two confronting spacer
plates are m~hin~d or molded to include aligned recesses which, when
arranged in facing relationship, provide a central air space 78 between the
second and third plates 70, 72. Space 78 is concen~ ;c with the plates 70 and
72, and with the gland body 56.
The packing seals 68 and 74 are solid disk-like members which may be
formed of rubber or other suitable m~t~n~l
With reference also to Figure 3, a radially eYt~n~ing hole or bore 80 is
5 forrned through the gland body and radially through the spacer plates 70 and
72 to commllni~te with the center space 78. The gland body is also axially
drilled to form an axial passageway 82 cYt~n~ling from passageway 80 to the
outer axial edge 84 of the gland body. The bore 82 a~j~ren~ to the edge 84 is
threaded to receive a sealing con~ or 86 which, in turn, corln~ to a
20 conduit 88 which extends to gas leakage monitoring apparatus (not shown in
Figure 2), as desl~nl)ed further below.
A plcs~ e plate 90 in~ludes a cylin~n~l body portion 92 and a radial
flange portion 94. The body portion 92 is sized to snugly fit within the gland
25 body 56 and the radial flange portion 94 is provided with a plurality of boltholes 96 which enable a plurality of bolts 98 to be threaded into the
co~ onding bolt holes 62 forrned in the gland body 54.
As shown in Figure 2, a single lead or wire W is shown penetrating
30 the generator wall 52 through the gland 50. Thus, the wire W which
2149693
inclu~eS~ for example, a .064, 14 AWG varnished metal strand 100 covered
with an inc~ ting sleeve 102, passes through the opening 60, and then through
the first spacer plate 66, first packing seal 68, second spacer plate 70, centerspace 78, the third spacer plate 72, second packing seal 74 and fourth spacer
5 plate 76. The in5ul~ing sleeve material 102 is removed from the wire for
those portions of the wire which extend through the packing seals 68 and 74
and adjacent portions, as best seen in Figure 2. The in~ ting sleeve 102
remains in place, however, within the space 78. While only one wire W is
shown exiting the generator, it will be appreciated that the size and
o configuration of the gland, in combination with the size of the opening 60,
allow many wires to exit the generator through the same gland if required.
With the wire W shown in place, the p.~ssulc plate 90 may be secured
to the outer end of the gland body 54 and tighte-~ed down via bolts 98. The
5 col,lpf~ssive forces exerted by the p~Saulc plate col,.~.ess the el~ within
the gland body and particularly the gasket 64 and the packing seals 68 and 74.
These colllpressive forces result in a 360 radial squeezing of the packing
seals 68 and 74 against the bare metal strand 100 in the stripped portions to
thereby p~ .ely seal the strand and thus prevent leakage of hydlugo, gas
20 along the strands.
Further in this regard, and with particular reference to Figure 4 (detail
A from Figure 2), the annular edge 104 of the p.es~ule plate 90 is beveled
and exerts uniform plessu.e on an O-ring 106 located between the fourth
2s spacer plate 76 and the inner end of the pressure plate. In turn, the p.esi~
plate 90 exerts uniform pressure on the plates 76, 72, 70 and 66. As a
result, uniform pressure is also applied to the packing seals 68 and 74 and
then to the wire W.
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By providing the center space 78 within the gland body 56, one is able
to detect any gas leakage through the first seal comprising the first and secondspacer plates 66 and 70 in combination with a packing seal 68, in that any gas
leaking beyond plate 70 into space 78 will flow via cQI-dllitc 80, 82 and 88 to
s gas detection apparatus similar to that shown rh-~m~tic~lly at 122 in Figure 5.
At the same time, the presence of a second sealing arrangement formed by the
third and fourth spacer plates 72 and 76 and second packing seal 74, insures
against gas leakage out of the generator.
0 With ,~fc.~,~ce now to Figure S, the present gland design permits a gas
leakage monitoring scheme to be set up to identify and isolate leaks in several
glands which may be spaced at various loc~ nc about thc gçn~rator. Thus,
in Figure 5, three glands 108, 110 and 112 are shown in an ~ng~om.ont
where conl;.-~,ous ,--on;~o~;ng of all three glands can occur cimnlt~n~oucly.
Thus, the gland 108 is conn~ted by gas leakage branch conduit 114 to a
common manifold conduit 116. Glands 110 and 112 are similarly connrct~
to the manifold conduit 116 by branch co~;d~ 118 and 120, l~i~ely.
Between the branch condllitc 114 and 118, the .I.~irold gland 116 innllldes a
first valve 122, and ~.OeA branch condllitc 114 and 118, the m~nifi~ki
conduit 116includes a second valve 124. The manifold conduit 116 e~ctends
beyond the glands to a conventional h~d~gen de~ecti~n device 126 which is
vented to ~..o~yk~ G at 128. In the event the gas det~tion device 126 detects
leakage, the op~.<,tor can selectively close the normally open valves 118 and
120 to pinpoin~ the source of the leakage. In this way, k~kage in any one of
2S the glands can be isolated and repaired before any cig~ifiç~nt danger arises by
reason of the leakage. At the same time, the utili7~tion of a double seal
design plc~ents gas leakage beyond the gland itself.
It will also be appr~iated from the new gland design illustrated in
30 Figures 3 and 5, that air can be ~mit~,d into the glands 108, 110 and 112
2149693
selectively via co~dl~it~ 114, 118 and 120, ~es~ .vely, to pll-s~ule test one ormore of the glands prior to start-up of the generator. This ability to presa~le
test the gland is, of course, equally applicable to single gland arrangements asshown in Figure 2. Thus, the present gland design provides distinct
5 advantages over the previously described conventional gland design.
While the invention has been described in co~n~ ;on with what is
pl~ tly considered to be the most pra~t~ and p~ef~ d embo~limpn~ it is
to be understood that the invention is not to be limited to the rlicrloc~d
0 embo~lim~nt but on the contrary, is intc~ndcd to cover vanous m~ific~ti~ nc
and equivalent arrangements in~luded within the spirit and scope of the
appended claims.
