Title: Fault-annuciating system for a transformer
Abstract: A preferred embodiment of a transformer includes a core, and a primary and a secondary winding positioned on the core so that the primary and secondary windings are inductively coupled when the primary winding is energized. The transformer also includes a sensor for measuring an operating parameter of the transformer, an audible signaling device, and an actuator for activating the audible signaling device when the operating parameter reaches a predetermined value.
Patent Number: 6,949,934 Issued on 09/27/2005 to Vu, et al.
| Inventors:
|
Vu; Tri D. (Apex, NC);
Oravsky; Joseph (Clayton, NC)
|
| Assignee:
|
ABB Technology AG (Zurich, CH)
|
| Appl. No.:
|
431286 |
| Filed:
|
May 7, 2003 |
| Current U.S. Class: |
324/547; 324/726 |
| Intern'l Class: |
G01R 031/06; G01R 029/20 |
| Field of Search: |
324/547,726,55,127,511
340/646
|
References Cited [Referenced By]
U.S. Patent Documents
| 3936699 | Feb., 1976 | Adams.
| |
| 4024436 | May., 1977 | Adams.
| |
| 4060803 | Nov., 1977 | Ashworth, Jr.
| |
| 4097852 | Jun., 1978 | Usry.
| |
| 4249170 | Feb., 1981 | Cham et al.
| |
| 4291204 | Sep., 1981 | Crick.
| |
| 4445457 | May., 1984 | Bargman.
| |
| 4654806 | Mar., 1987 | Poyser et al.
| |
| 4755805 | Jul., 1988 | Chau.
| |
| 5534853 | Jul., 1996 | Pioch.
| |
| 6429662 | Aug., 2002 | Cuk et al.
| |
| Foreign Patent Documents |
| 0 072 882 | Mar., 1983 | EP.
| |
| 0 253 447 | Jan., 1988 | EP.
| |
| 0 448 619 | Oct., 1991 | EP.
| |
Other References
"Single Phase Overhead Distribution Transformers", ABB, Inc., Distribution
Transformers, Athens, GA, Jefferson City, MO., Jan. 2002, 2 Pages.
|
Primary Examiner: Nguyen; Vincent Q.
Assistant Examiner: He; Amy
Attorney, Agent or Firm: Woodcock Washburn LLP
Claims
1. A transformer, comprising:
a core;
a primary and a secondary winding positioned on the core so that the primary
and secondary windings are inductively coupled when the primary winding is energized;
a sensor for measuring an operating parameter of the transformer;
an audible signaling device comprising a whistle, a pressure regulator, and a
canister for holding a pressurized fluid, the canister being in fluid communication
with the whistle on a selective basis by way of the pressure regulator; and
an actuator for activating the audible signaling device when the operating parameter
reaches a predetermined value.
2. The transformer of claim 1, wherein the operating parameter is an oil temperature
of the transformer and the sensor is a temperature sensor.
3. The transformer of claim 2, further comprising a battery for energizing the
actuator and the temperature sensor.
4. The transformer of claim 1, wherein the pressure regulator permits the pressurized
fluid to flow from the canister to the whistle when the audible signaling device
is activated.
5. The transformer of claim 4, wherein the pressure regulator maintains a pressure
of the pressurized fluid reaching the whistle at a substantially constant level.
6. The transformer of claim 1, wherein the actuator is an electro-mechanical actuator.
7. The transformer of claim 1, further comprising a processor electrically coupled
to the sensor and the actuator, the processor generating an output that causes
the actuator to activate the audible signaling device when the operating parameter
reaches the predetermined value.
8. The transformer of claim 1, further comprising a casing for housing the core
and the primary and secondary windings, and a cover for the casing, wherein the
audible signaling device is mounted on an outer surface of one of the casing and
the cover.
9. The transformer of claim 8, wherein the sensor is mounted on an inner surface
of the casing.
10. The transformer of claim 8, wherein the sensor and the actuator comprise
a mechanical sensor/actuator.
11. The transformer of claim 10, wherein the sensor/actuator comprises a rod,
and a housing mounted on and extending through the one of the casing and the cover,
the housing has a through hole formed therein for receiving the rod, the rod is
movable between a retracted position and an extended position in relation to the
housing in response to an overpressure condition within the casing, and movement
of the rod from the retracted position to the extended position activates the audible
signaling device.
12. The transformer of claim 11, further comprising a linkage mechanically coupled
to the rod and the audible signaling device, wherein movement of the rod from the
retracted position to the extended position causes the linkage to move a switch
on the audible signaling device thereby activating the audible signaling device.
13. The transformer of claim 1, further comprising a linkage mechanically coupled
to the actuator and the audible signaling device, wherein the actuator causes the
linkage to move a switch on the audible signaling device when the operating parameter
reaches the predetermined value thereby activating the audible signaling device.
14. The transformer of claim 1, wherein the core comprises a first and a second
winding leg and a first and a second yoke, the first yoke is fixedly coupled to
respective first ends of the first and second winding legs, the second yoke is
fixedly coupled to respective second ends of the first and second winding legs,
the first winding is positioned on the first winding leg, and the second winding
is positioned on the second winding leg.
15. The transformer of claim 1, wherein the audible signaling device comprises
an electronic alarm.
16. The transformer of claim 15, wherein the actuator comprises a processor for
activating the electronic alarm when the operating parameter reaches the predetermined value.
17. The transformer of claim 1, further comprising a first terminal electrically
coupled to the primary winding and a second terminal electrically coupled to the
secondary winding.
18. A transformer comprising a core, a primary and a secondary winding positioned
on the core, and an audible signaling device responsive to the occurrence of a
fault in the transformer, the audible signaling device comprising a whistle, a
pressure regulator, and a canister for holding a pressurized fluid, wherein the
canister is in fluid communication with the whistle on a selective basis by way
of the pressure regulator.
19. The transformer of claim 18, further comprising an actuator for activating
the audible signaling device.
20. The transformer of claim 18, further comprising a sensor for measuring an
operating parameter of the transformer.
21. The transformer of claim 18, further comprising a casing for housing the
core and the primary and secondary windings, and a cover for the casing, wherein
the audible signaling device is mounted on an outer surface of one of the casing
and the cover.
22. The transformer of claim 21, further comprising a mechanical sensor/actuator
comprising a rod, and a housing mounted on and extending through the one of the
casing and the cover, the housing has a through hole formed therein for receiving
the rod, the rod is movable between a retracted position and an extended position
in relation to the housing in response to an overpressure condition within the
casing, and movement of the rod from the retracted position to the extended position
activates the audible signaling device.
23. The transformer of claim 22, further comprising a linkage mechanically coupled
to the rod and the audible signaling device, wherein movement of the rod from the
retracted position to the extended position causes the linkage to move a switch
on the audible signaling device thereby activating the audible signaling device.
24. A transformer, comprising:
a core;
a primary winding positioned around a first winding leg of the core;
a secondary winding positioned around one of the first winding leg and a second
winding leg of the core;
a casing for housing the core and the primary and secondary windings;
a cover for the casing;
an audible signaling device mounted on one of the casing and the cover and comprising
a whistle, a pressure regulator, and a canister for holding a pressurized fluid;
a sensor for measuring an operating parameter of the transformer; and
an actuator for causing the pressure regulator to permit the pressurized fluid
to flow from the canister to the whistle when the operating parameter reaches a
predetermined value.
25. The transformer of claim 24, wherein the sensor and the actuator comprise
a mechanical sensor/actuator comprising a rod, and a housing mounted on and extending
through the one of the casing and the cover, the housing has a through hole formed
therein for receiving the rod, the rod is movable between a retracted position
and an extended position in relation to the housing in response to an overpressure
condition within the casing, and movement of the rod from the retracted position
to the extended position activates the audible signaling device.
26. The transformer of claim 25, further comprising a linkage mechanically coupled
to the rod and the audible signaling device, wherein movement of the rod from the
retracted position to the extended position causes the linkage to move a switch
on the pressure regulator thereby activating the whistle.
27. A transformer, comprising:
a core;
a primary and a secondary winding positioned on the core so that the primary
and secondary windings are inductively coupled when the primary winding is energized;
a casing for housing the core and the primary and secondary windings;
a cover for the casing;
an audible signaling device mounted on an outer surface of one of the casing
and the cover; and
a mechanical sensor/actuator for measuring an operating parameter of the transformer
and activating the audible signaling device when the operating parameter reaches
a predetermined value, wherein the mechanical sensor/actuator comprises a rod,
and a housing mounted on and extending through the one of the casing and the cover,
the housing has a through hole formed therein for receiving the rod, the rod is
movable between a retracted position and an extended position in relation to the
housing in response to an overpressure condition within the casing, and movement
of the rod from the retracted position to the extended position activates the audible
signaling device.
28. A transformer comprising:
a core;
a primary and a secondary winding positioned on the core;
a casing for housing the core and the primary and secondary windings;
a cover for the casing;
an audible signaling device responsive to the occurrence of a fault in the transformer
and mounted on an outer surface of one of the casing and the cover; and
a mechanical sensor/actuator comprising a rod, and a housing mounted on and extending
through the one of the casing and the cover, wherein the housing has a through
hole formed therein for receiving the rod, the rod is movable between a retracted
position and an extended position in relation to the housing in response to an
overpressure condition within the casing, and movement of the rod from the retracted
position to the extended position activates the audible signaling device.
Description
FIELD OF THE INVENTION
The present invention relates generally to transformers and, more specifically,
to a fault-annunciating system that provides an audible indication of a transformer fault.
BACKGROUND OF THE INVENTION
Distribution transformers are often equipped with some type of internal
fault detector for providing a visual indication that a fault has occurred in the
transformer. For example, one commonly-used type of internal fault detector senses
the temperature or pressure at one or more locations within the transformer. (A
substantial increase in the operating temperature or pressure of transformer is
usually indicative of a fault therein.) The internal fault detector causes some
type of mechanical component, such as a pole, to extend upward from the top of
the transformer when the monitored temperature or pressure exceeds a predetermined
value. The extended pole functions as a visual indication that the transformer
has experienced a fault.
A faulty transformer typically results in a power outage or other anomaly in
the
vicinity of the transformer. A repair crew from the utility company is usually
dispatched to the affected area to locate and repair the faulty transformer. The
repair crew visually scans the various transformers in the area until the repair
crew sights the visual fault indication, i.e., the extended pole, on the faulty
transformer. The faulty transformer, having thus been located, can thereafter be repaired.
The use of a visual indication to identify a faulty transformer has certain drawbacks.
For example, a repair crew attempting to locate a faulty pole-mounted transformer
can experience muscle strain or fatigue from repeatedly looking upward at a relatively
steep angle for the fault indication. Moreover, the need to visually scan for a
fault indication can distract the driver of the vehicle carrying the repair crew,
thereby creating a safety hazard. Also, a visual fault indication sometimes cannot
be seen from certain perspectives, especially on pole-mounted transformers.
A visual fault indication also can be difficult or impossible to see at night
and
under adverse weather conditions, e.g., fog or heavy rain. Furthermore, a visual
indication, in general, can only be detected when the repair crew is in relatively
close proximity of the transformer, i.e., when the faulty transformer is within
sight of the repair crew.
SUMMARY OF THE INVENTION
A preferred embodiment of a transformer comprises a core, and a primary and a
secondary
winding positioned on the core so that the primary and secondary windings are inductively
coupled when the primary winding is energized. The transformer also comprises a
sensor for measuring an operating parameter of the transformer, an audible signaling
device, and an actuator for activating the audible signaling device when the operating
parameter reaches a predetermined value.
Another preferred embodiment of a transformer comprises a core, a primary
and a secondary winding positioned on the core, and an audible signaling device
responsive to the occurrence of a fault in the transformer.
Another preferred embodiment of a transformer comprises a core, a primary
winding positioned around a first winding leg of the core, and a secondary winding
positioned around one of the first winding leg and a second winding leg of the
core. The transformer also comprises a casing for housing the core and the primary
and secondary windings, and a cover for the casing.
The transformer further comprises an audible signaling device mounted on one
of the casing and the cover. The transformer comprises whistle, a pressure regulator,
and a canister for holding a pressurized fluid. The transformer also comprises
a sensor for measuring an operating parameter of the transformer, and an actuator
for causing the pressure regulator to permit the pressurized fluid to flow from
the canister to the whistle when the operating parameter reaches a predetermined value.
A preferred method for locating a faulty transformer in an area of a power outage
comprises moving to within audible range of an audible signaling device of each
of a plurality of transformers in the area, and listening for an audible fault
indication produced by the audible signaling device of the faulty transformer.
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing summary, as well as the following detailed description of a preferred
embodiment, is better understood when read in conjunction with the appended drawings.
For the purpose of illustrating the invention, the drawings show an embodiment
that is presently preferred. The invention is not limited, however, to the specific
instrumentalities disclosed in the drawings. In the drawings:
FIG. 1 is a diagrammatic illustration of a transformer comprising a preferred
embodiment of a fault-annunciating system, showing a casing and a cover of the
transformer in cross section;
FIG. 2 is a block diagram of the transformer shown in FIG. 1;
FIG. 3 is a diagrammatic illustration of an alternative embodiment of the transformer
shown in FIG. 1, showing a casing and a cover of the transformer in cross section;
FIG. 4A is a magnified view of the area designated "A" in FIG. 3, before activation
of a fault-annunciation system of the transformer;
FIG. 4B is a magnified view of the area designated "A" in FIG. 3, after activation
of the fault-annunciation system; and
FIG. 5 is a diagrammatic illustration of another alternative embodiment of the
transformer shown in FIG. 1, showing a casing and a cover of the transformer in
cross section.
DESCRIPTION OF PREFERRED EMBODIMENTS
FIGS. 1 and 2 depict a distribution transformer
10 comprising a preferred
embodiment of a fault-annunciating system
12. The transformer
10
is a single-phase, oil-filled, core-type transformer suitable for a pole-top installation.
The fault-annunciating system
12 is described herein in connection with
the transformer
10 for exemplary purposes only. The fault-annunciating system
12 can be used with virtually any type of transformer, including power transformers,
dry, multi-phase, and shell-type transformers, and transformers suitable for mounting
on pads at electrical substations.
The fault-annunciating system
12, as explained below, generates an audible
signal (sound) in response to the occurrence of a fault within the transformer
10. The audible signal can alert a repair crew in the vicinity of the transformer
10 to the presence of a fault in that particular transformer
10.
The transformer
10 comprises a laminated core
14 (see FIG. 1).
The core
14 comprises a first winding leg
14a, a second winding
leg
14b, an upper yoke
14c, and a lower yoke
14d.
Opposing ends of each of the upper and lower yokes
14c,
14d
are secured to the first and second winding legs
14a,
14b
as shown in FIG. 1.
The transformer
10 further comprises a primary winding
16 positioned
around the first winding leg
14a, and a secondary winding
18
positioned around the second winding leg
14b. It should be noted
that the primary and secondary windings
16,
18 can be concentrically
disposed around a single winding leg in alternative embodiments of the transformer
10.
The transformer
10 also comprises a casing
20, and a cover
22
that mates with and covers the casing
20. The core
14 and the windings
16,
18 are housed within the casing
20. The core
14
and the primary and secondary windings
16,
18 are immersed in oil
within the casing
20. The oil helps to cool and electrically insulate the
core
14 and the primary and secondary windings
16,
18. (The
oil is not shown in the figures, for clarity.)
A gasket
23 is positioned between the casing
20 and the cover
22
so that a substantially airtight seal is formed between the casing
20 and
the cover
22. The casing
20, cover
22, and the gasket
23
thus isolate the core
14 and the primary and secondary windings
16,
18 from the environment around the transformer
10.
The transformer
10 further comprises a first terminal
24 electrically
coupled to the primary winding
16, and a second terminal
26 electrically
coupled to the secondary winding
18. (The electrical connections between
the various components of the transformer
10 are depicted in FIG. 2. The
electrical connections are not depicted in FIG. 1, for clarity.)
The first and second terminals
24,
26 each extend through respective
penetrations formed in the cover
22. The first terminal
24 is electrically
isolated from the cover
22 by a first bushing
28. The second terminal
26 is electrically isolated from the cover
22 by a second bushing
29.
The primary winding
16 is electrically coupled to an alternating-current
power source, such as a substation of a power grid (not shown), by way of the first
terminal
24. The secondary winding
18 is electrically coupled to
a load, such as an electrical system of a residential dwelling (also not shown),
by way of the second terminal
26.
The primary and secondary windings
16,
18 are inductively coupled
via the core
14 when the primary winding
16 is energized by the power
source. In particular, the alternating voltage across the primary winding
16
produces an alternating magnetic flux in the core
14. The alternating magnetic
flux induces an alternating voltage across the secondary winding
18 (and
the load connected thereto).
The voltage across each of the primary and secondary windings
16,
18
is proportional to the number of turns in the respective primary and secondary
windings
16,
18. The current in each of the primary and secondary
windings
16,
18 is inversely proportional to the number of turns
in the respective primary and secondary windings
16,
18.
Further details of the transformer
10 (other than the following details
of the fault-annunciating system
12) are not necessary to an understanding
of the invention, and therefore are not included herein. Moreover, it should be
noted that the above-described details of the transformer
10 are presented
for illustrative purposes only. The fault-annunciating system
12 can be
used in conjunction with transformers of virtually any configuration.
The fault-annunciating system
12 comprises an actuator
40, a temperature
sensor
42, a processor
44, e.g., a microprocessor, and an audible
signaling device
45. The fault annunciating system
12, as discussed
below, generates an audible signal in response to the occurrence of a fault in
the transformer
10. The audible signal can be used by a repair crew from
the utility company to locate the faulty transformer
10 so that corrective
action can be initiated.
The fault-annunciating system
12 preferably comprises a rechargeable battery
56 for powering the various electrical components of the fault-annunciating
system
12. The battery
56 is preferably recharged using the secondary
winding
18 as a source of power.
The audible signaling device
45 is preferably mounted on the outer surface
of the casing
20, as shown in FIG. 1. (The audible signaling device
45
can be mounted on an outer surface of the cover
22 in alternative embodiments.)
The audible signaling device
45 can comprise, for example, a whistle
46,
a pressure-regulating valve
48, and a canister
50. The canister
50
holds a pressurized fluid, e.g., gaseous nitrogen. The canister
50 fluidly
communicates with the whistle
46 on a selective basis by way of the pressure-regulating
valve
48. More particularly, the pressure-regulating valve
48 permits
the pressurized fluid to flow from the canister
50 to the whistle
46
when the pressure-regulating valve
48 is activated. The resulting flow of
fluid through the whistle
46 causes the whistle
46 to generate an
audible signal. The significance of this feature is discussed below.
The pressure-regulating valve
48 maintains the pressure of the fluid exiting
the canister
50 at a substantially constant level. Hence, the pressure of
the fluid entering the whistle
46 (and the resulting volume of the whistle
46) can remain substantially constant.
Virtually any type of conventional pressure-regulating valve capable of
providing the pressure and flow-rate required by the whistle
46 can be used
as the pressure-regulating valve
48. For example, the pressure-regulating
valve
48 can be of the self-regulating type that operates based on pre-set
spring tension therein. Alternatively, the pressure-regulating valve
48
can be actuated by a separate valve controller (not shown).
The temperature sensor
42 measures the temperature of the oil within the
transformer
10. The temperature sensor
42 can be mounted on an inner
surface of the casing
20, as shown in FIG. 1. Virtually any type of conventional
temperature sensor can be use as the temperature sensor
42 including, for
example, a thermocouple, thermistor, resistance temperature detector, etc. The
temperature sensor
42 is electrically coupled to the processor
44,
and thus provides the processor
44 with an input corresponding the oil temperature
within the transformer
10.
The actuator
40 activates the pressure-regulating valve
48. More
particularly, the actuator
40 is mechanically coupled to the pressure-regulating
valve
48 so that the actuator
40 can actuate an on-off feature on
the pressure-regulating valve
48. For example, the actuator
40 can
be mechanically coupled to a switch
52 of the pressure-regulating valve
48 by a linkage
54 (see FIG. 1). Movement of the linkage
54
by the actuator
40 causes the switch
52 to move between an "off"
and an "on" position. Movement of the switch
52 to the "on" position activates
the pressure-regulating valve
48. The pressure-regulating valve
48,
once activated, permits pressurized fluid to flow from the canister
50 to
the whistle
46 as described above.
The actuator
40 is electrically coupled to the processor
44, and
is responsive to commands from the processor
44. More specifically, the
processor
44 can issue commands to the actuator
40 that cause the
actuator
40 to move the switch
52 between its on and off positions.
The processor
44 can thereby control whether the pressurized air from the
canister flows to the whistle
46.
Virtually any type of conventional actuator capable of responding to the
commands of the processor
44 in the above-described manner can be used as
the actuator
40.
For example, a conventional electro-mechanical actuator can be used as the actuator
40. The electromechanical actuator can comprise a shaft mechanically coupled
to the linkage
54 and having a magnetic sleeve attached to an outer surface
thereof (not shown). The magnetic sleeve can be positioned within a coil (also
not shown). Energization of the coil in response to a commands from the processor
44 can generate a magnetic field that causes the magnetic sleeve (and the
attached shaft) to move in relation to the coil. Movement of the shaft causes a
corresponding movement in the linkage
54 that, in turn, moves the switch
60 between its "off" and "on" positions.
Moreover, the actuator
40 and processor
44 can be used to
actively control the pressure-regulating valve
48 in applications where
the pressure-regulating valve
48 is not of the self-regulating type.
The processor
44 monitors the oil temperature within the transformer
10,
as noted previously. The processor
44 commands the actuator
40 to
move the switch
60 to its "on" position when the oil temperature reaches,
i.e., increases to, a predetermined value. Moving the switch to its "on" position,
as discussed above, initiates the flow of pressurized air to the whistle
46
and thereby causes the whistle
46 to produce an audible signal.
A substantial increase in the oil temperature within a transformer such as the
transformer
10 is usually indicative of a fault condition. The fault-annunciation
system
12 reacts to such increases by issuing an audible signal. The audible
signal issued by the fault-annunciation system
12 can thus indicate that
a fault has occurred within the transformer
10.
It should be noted that the particular operating parameter or parameters used
as an indication of a fault in the transformer
10 is application dependent.
Operating parameters other than oil temperature can be used as a basis for activating
the fault-annunciation system
12 in alternative embodiments. For example,
alternative embodiments of the fault-annunciation system
12 can be responsive
to pressure. In particular, a conventional pneumatic pressure sensor (not shown)
can be used in lieu of the temperature sensor
42. The processor
44
can be programmed to monitor the air pressure within the transformer
10.
The processor
44 can command the actuator
40 to move the switch
60
to its "on" position when the pressure reaches a predetermined value, thereby initiating
the flow of pressurized air to the whistle
46 and causing the whistle
46
to produce an audible signal.
A repair crew from the utility company can use the sound of the whistle
46
to identify a particular transformer that has experienced a fault. More particularly,
the repair crew can be sent to the general vicinity in which a power outage or
other abnormality has occurred due a faulty transformer such as the transformer
10. The sound of the whistle
46 can lead the repair crew to the faulty
transformer
10, or at the very least, can draw the attention of the repair
crew to the faulty transformer
10 as the repair crew drives by the transformer
10.
The repair crew, once identifying the faulty transformer
10, can repair
the transformer
10 or otherwise correct the condition that lead to the occurrence
of the fault. Following the repair of the transformer
10, the fault-annunciating
system
12 can be rendered ready for further use by replacing the discharged
canister
50 with a fully-charged canister
50.
The canister
50 can be sized to hold a sufficient amount of fluid to activate
the whistle
46 for a predetermined period of time. The predetermined period
of time, or activation period, should be sufficient to permit the repair crew to
reach the transformer
10 following the occurrence of a fault. The response
time of the repair crew is application-dependent, and can vary with factors such
as the location of the transformer in relation to the base of operations of the
repair crew, the number of transformers located along the route followed by the
repair crew, etc. A specific value for the activation period of the whistle
46
therefore is not specified herein.
The volume, i.e., the sound intensity or dB level, of the whistle
46 should
be sufficient to allow a repair crew to hear the whistle
46 when the repair
crew is in the vicinity the transformer, or at the very least, as the repair crew
drives by the pole on which the transformer
10 is mounted.
The optimal volume for the whistle
46 is application dependent. For example,
where the transformer
10 is to be used in a residential location, it may
be desirable for the whistle
46 to have a relatively low volume to avoid
disturbing residents located near the transformer
10. Conversely, it may
be desirable for the whistle to have a relatively high volume where the transformer
10 is to be used in remote or sparsely-populated locations, thus making
it easier for the repair crew to locate the transformer
10 once a fault
occurs therein.
The whistle
46 can be chosen so as to make virtually any tone that can
be recognized by a repair crew as an indication that the fault-annunciation system
12 of a particular transformer
10 has been activated.
The audible indication generated by the fault-annunciating system
12 can
potentially eliminate the need for a repair crew to visually scan multiple transformers
for a fault indication. Eliminating the need for a visual scan can eliminate or
reduce muscle strain or fatigue on the repair crew caused by the need to repeatedly
look upward, at a relatively steep angle, to visually acquire a fault indication
from a pole-mounted transformer. Moreover, eliminating the need for a visual scan
can reduce the potential for the driver of the vehicle carrying the repair crew
to become distracted while attempting to visually acquire the fault indication.
The audible fault indication provided by the fault-annunciating system
12
can, in general, be more readily detected at night and under adverse weather conditions,
e.g., fog or heavy rain, than a visual fault indication. Moreover, the audible
fault indication can potentially be detected when the transformer
10 is
not in sight of the repair crew. Thus, the audible fault indication can potentially
be detected at a greater distance from the transformer
10 than a visual
indication. Also, detection of the audible fault indication, in general, does not
substantially depend on the perspective of the repair crew in relation to the transformer.
It is to be understood that even though numerous characteristics of the present
invention have been set forth in the foregoing description, the disclosure is illustrative
only and changes may be made in detail within the principles of the invention to
the full extent indicated by the broad general meaning of the terms in which the
appended claims are expressed.
For example, alternative embodiments can comprise a mechanical temperature or
pressure sensor and a mechanical actuator. An example of such a system is depicted
in FIGS. 3-4B. FIGS. 3-4B depict a transformer
10a comprising a fault-annunciating
system
80. The fault-annunciating system
80 comprises a mechanical
pressure sensor/actuator
82. (Components common the transformer
10a
and the transformer
10 are denoted by common reference numerals in the figures.)
The pressure sensor/actuator
82 comprises a rod
83 and a housing
84. The housing
84 is mounted on, and extends though, the casing
20. (The fault annunciating system
80 can be mounted on the cover
22 in the alternative.) The housing
84 has a surface
84a
that defines a through hole. The through hole receives the rod
83 so
that a portion of a circumferentially-extending outer surface
83a of
the rod
83 contacts the surface
84a.
The rod
83 moves from a first (retracted) position (FIGS. 3 and 4A) to
a second (extended) position (FIG. 4B) in response to an overpressure condition
within the casing
20. The selective movement of the rod
83 can be
achieved, for example, by selecting appropriate values for the coefficients of
friction of the surfaces
83a,
84a.
The rod
83 is mechanically coupled to the switch
52 of the pressure-regulating
valve
48 by a linkage
86. Movement of the rod
83 from its
retracted to its extended position causes a corresponding movement of the linkage
86. Movement of the linkage
86, in turn, moves the switch
52
from its "off" to its "on" position, thereby activating the pressure-regulating
valve
48 and initiating flow of the pressurized fluid from the canister
50 to the whistle
46.
Virtually any type of audible signaling device capable of generating a
sound at the required volume and for the required duration can be used in lieu
of the audible signaling device
45 in alternative embodiments.
For example, FIG. 5 depicts a transformer
10b comprising a fault-annunciating
system
70. (Components common the transformer
10b and the
transformer
10 are denoted by common reference numerals in the figures.)
The fault-annunciating system
70 comprises an electronic audible signaling
device
72 such as an electronic alarm, and an electronic actuator
74
comprising a processor. The actuator
74 generates and sends an electrical
signal to the audible signaling device
72 when the oil temperature in the
transformer
10b, as measured by the temperature sensor
42,
reaches a predetermined value. (Other alternative embodiments can use the electronic
audible signaling device
72 and the electronic actuator
74 in conjunction
with a pressure sensor (not shown)).
Other alternative embodiments can include an electronic actuator such as the
actuator
74 and a mechanical audible signaling device such as the audible
signaling device
45. Further alternative embodiments can include an actuator
integrated into the audible signaling device.
*
