CA1119669A - Precipitation detection system - Google Patents
Precipitation detection systemInfo
- Publication number
- CA1119669A CA1119669A CA000314381A CA314381A CA1119669A CA 1119669 A CA1119669 A CA 1119669A CA 000314381 A CA000314381 A CA 000314381A CA 314381 A CA314381 A CA 314381A CA 1119669 A CA1119669 A CA 1119669A
- Authority
- CA
- Canada
- Prior art keywords
- wires
- head
- body member
- resistor
- sets
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
- G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
- G01N27/048—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance for determining moisture content of the material
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01W—METEOROLOGY
- G01W1/00—Meteorology
Landscapes
- Chemical & Material Sciences (AREA)
- Environmental & Geological Engineering (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Physics & Mathematics (AREA)
- Ecology (AREA)
- Environmental Sciences (AREA)
- Atmospheric Sciences (AREA)
- Engineering & Computer Science (AREA)
- Electrochemistry (AREA)
- Biodiversity & Conservation Biology (AREA)
- Health & Medical Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
Moisture detection systems are known in which interleaved sets of spaced apart wires are connected to a sensing circuit which is activated when moisture bridges wires in the two sets. It is also known to provide a heater resistor so that the system may detect solid precipitation such as snow. However, in some systems, the sensing head has to be of large size and efficient operation has not been practical over a wide range of freez-ing temperatures. The present invention overcomes these problems by pro-viding a compact sensing head comprising sets of wires encapsulated in epoxy and surrounding a small wire wound heating resistor. The heating resistor melts snow or other solid precipitation and the epoxy is selected to have the same thermal coefficient of expansion as the body member of the head so that there is good heat transfer to the wires and the epoxy does not pull away from the body member of the head. A heat dissipating resistor is connected in series with the resistor in the head at a first predetermined low temperature so that the head is kept warm. At an even lower temperature, a thermostat cuts out the heat dissipating resistor so that there is increased current flow to the heater in the sensor head, enabling it to operate down to a very low temperature.
Moisture detection systems are known in which interleaved sets of spaced apart wires are connected to a sensing circuit which is activated when moisture bridges wires in the two sets. It is also known to provide a heater resistor so that the system may detect solid precipitation such as snow. However, in some systems, the sensing head has to be of large size and efficient operation has not been practical over a wide range of freez-ing temperatures. The present invention overcomes these problems by pro-viding a compact sensing head comprising sets of wires encapsulated in epoxy and surrounding a small wire wound heating resistor. The heating resistor melts snow or other solid precipitation and the epoxy is selected to have the same thermal coefficient of expansion as the body member of the head so that there is good heat transfer to the wires and the epoxy does not pull away from the body member of the head. A heat dissipating resistor is connected in series with the resistor in the head at a first predetermined low temperature so that the head is kept warm. At an even lower temperature, a thermostat cuts out the heat dissipating resistor so that there is increased current flow to the heater in the sensor head, enabling it to operate down to a very low temperature.
Description
6~
This invention relates to a moisture detection head and moisture detection system.
It is known in the prior art to detect moisture by using a sensor head comprisin~ spaced apart ~ires or sets of ~Yires connected to sensing circuitry. If moisture bridges the wires, current ~lo~s between them and is detected by the sensing circuitry. However, some such circuits are only able to detect liquid precipitation, i.e. rain, and are not useful for detect-ing solid precipitation such as snow or freezing rain. In many circumstances, it is hignly desirable to be able to detect solid precipita~ion so that appro-priate action may be taken. ~or example, a railway switch in a remote areacan be rendered inoperative by snow or freezing rain and it is desirable to have means for detecting snow or freezing rain so that an alarm may be given or a heater turned on to keep the switch cleared. Obviously, there are many other situations where such detection is desirable, so as to keep radar, microwave or other communication equipment free of ice.
It is known in the prior art to use a heater resistor so that the sensor head may be warmed to melt snow or ice. However, such a haad has tended to be of large size in order to accommodate a large heater resistor. Further-more, at only moderately low temperatures, the heater resistor may generate far more heat than is actually necessary. The present invention overcomes - these problems and provides a small size sensor head capable of operating over a wide range of low temperatures, e.g. from about the fraezing point down to -40C. The sensor head according to the invention utilizes a small wire wound resistor which, at moderately low temperatures, is connected in series with another, heat dissipating, resistor so that the sensor head does not become unduly warm. Below a certain predetermined temperature~ how-ever, a thermostat closes a switch to bypass the heat dissipating resistor so that full current is supplied to the heater resistor in the sensor head, , g6~
enabling it to operate down to a very low temperature.
Thus, in accordance with one aspect of the invention, there is pro~
vided a moisture detection head comprising first and second lnterleaved, spaced apart, sets of generally parallel conductive wires, said wires each having a generally flat top portion and two downwardly extending end leg portions, the leg portions being secu:red to a printed circuit board, the printed circuit board and sets of wires defining a space in which is secured a wire would heater resistor, the printed circuit board and sets oE wires being contained in a hollow metal body member filled with electrically insul-ating epoxy encapsulating material up to a predetermined level so that the top portions of the wires are exposed, said body member being surrounded by a ring member having a longitudinally extending slot, said ring member extending above and below said predetermined level whereby said ring member provides protection against debris collecting on the exposed top portions of the wires and allows excess water to drain through said slot, said epoxy encapsulating material having a coefficient of thermal expansion substan-tially identical to that of said body member.
.:
.
- ,~
- . , ~ .
. : '' '.' .: -The invention will now be further described in con~unction with the accompanying drawings, in which:
Figure 1 is a block diagram of a system according to the invention for detecting solid precipitation, Figure 2 is a detailed schematic diagram oE a system according to the invention for detecting solid precipitation, Figure 3 is an exploded view of the moisture detection head accord-ing to the invention, Figure 4 is a top view of the moisture detection head according to the invention, and Figure 5 is a cross sectional view along the line A-A of Figure 4.
Referring to Figure 1, the sensor head is indicated at 3 in associa-tion with a heater resistor 13. The power supply 1 is connected to the ~-: heater resistor 13 and to the sensor head 3 through a heater control thermo-stat 2. When moisture is detected by the sensor head 3, current flows from the power supply 1 and this turns on a transistor switch 4 (actually an SCR
in the preferred embodiment) and, if the amblent temperature thermostat 5 is closed, current flows to a relay switch 6 to turn on an alarm 7. Although an alarm is shown in the drawing, it will be obvious that the relay switch 6 could also be used to turn on a heater to melt snow or ice, e.g. on a parking lot, raliway switch, etc.
Referring to Figure 2, the sensor head 3 comprises a grid 12 includ-ing first and second interleaved, spaced apart, sets 10 and 11 of generally parallel conductive wires. Power is applied across the grid 12 by the power supply 1 compris:ing a transformer Tl which, for example, has its primary ~1 :
'' ' ' : ` ~ '. ,` ,`" , ;
.
- . : . .. .
- ~
., 966~31 winding 30 supplied with 120 volts ~C and produces, for example, 27 volts AC at the output of its secondary winding 31. ~ capacitor 29 connected across the secondary 31 serves as a filter.
Referring to Figure 2, the thermostatically controlled switch 2 is normally open, that is, it is open at temperatures above about -12C.
Power is thus applied to wires ll via line 32, resistors 21 and 22 and line l~. Wires 10 connect via line 17 to the other side of the secondary 31 of transformer ~1. If moisture shoulcl bridge the wires 10 and ll, currentwillflow between them and the resulting voltage drop across resistor 21 will be applied through diode 23 to the gate of SCR 24, thus turning it on, assuming thermostat 5 to be closed. Current will thus flow through the SCR 24 and relay 27 to activate the external alarm circuit~
It will be seen that if the temperature drops below -12C, the thermostatically controlled switch 2 will close and bypass the heat dissi-pating resistor 20J thus resulting in increased current flowing to the resis-tor 13 in head 3. This action enables the head 3 to melt snow or ice down to a very low temperature, e.g. -40C. On the other hand, when the tempera-ture is above -12C, the head 3 is not heated to an unnecessary degree.
The inherent resistance of the grid 12 decreases within increasing presence of melted precipitation so that current developed through the series circuit of the grid 12 and resistors 21 and 22 increases with a constant voltage until the grid is completely inundated with water. The values of resistors 21 and 22 are calibrated against the changing series resistance of the grid 12 to produce a voltage drop across resistor 21 of sufficient level to trigger the SCR 24 into conduction. Diode 23 serves as a coupler as wel]. as rectifying the supply voltage in order to satisfy the direct current t:rigger requirements of the SCR 24.
When the S(:R 24 is triggered into conduction, alternating current - ' ':
-present on the cathode is rectified as it passes through to the anode thusenergi~in~ ti~e relay switch 27. Resistor 25 and capacitor 26 together serve as a line filter to protect the SCR from transient line surges. Diode 28 rectifies any chatter produced by the contacts of relay 27. In operation, when the voltage level at the output of the voltage divider and rectifier rèaches a ~iven value, the alarm will be activated providing the ambient temperature thermostat 5 is closedJ indicating that an undesirable form of precipitation is imminent. Thermostat 5 opens above about -~2C so that the alarm is not activated if the precipitation is simply rain. That is, the alarm is unnecessary when the ambient temperature is above the freezing point.
Referring to Figure 3, the moisture detection head is seen to com-prise first and second interleaved, spaced apart, sets of generally parallel conductive wires 10 and 11, the wires each having a generally flat top por-tion and two downwardly extending end leg portions. The leg portions are secured to a printed circuit board 9, the printed circuit board and sets of wires defining a space in which is secured a wire wo~md heater resistor 13. A wire wound resistor is used because it is capable of prod~lcing suf-ficient heat while being relatively small in size.
The printed circuit board 9 and sets of wires are contained in a hollow metal body member 3 filled with electrically insulating epoxy encap-; sulating material 16 ~Figure 4) up to a predetermined level so that the top portions of the wires 10 and 11 are exposed~ The body member is surrounded by a ring member 15 having a longitudinally extending slot 40, the ring member 15 extending abcve and below the predetermined level 41 ~Figure 5) whereby the ring member provides protection against foreign materials collecting on the exposed portions of the wires and allows excess water to drain through the slot 40.
The epoxy encapsulating material, which fills the body 3 up to level ; .
- ': . : , - , , .
, . , . ''' . - , . , ~ ' -~
' - '.
966~
41, is selected to have a coefficient o thermal expansion substantially identical to that of the body member 3. This is so that the sensor head may operate over a wide range of temperatures without the encapsulating material pulling away from the body member 3. The body member 3 is prefer-ably of brass, in which case the encapsulating material preferred is that sold under the trade mark Stycast Epoxy Casting Resin by Emerson-Cuming of Canton, ~lassachusetts. This is a high thermal K resin. The Epoxy Casting Resin used is Stycast 2850-FT and the hardner is catalyst number 11.
The ~ires 10 and 11 are preferably of gold clad stainless steel for good electrical and heat conductivity and resistance to corrosion.
Preferably the printed circuit board 9 sits on a fiber washer 8 within the body 3. Also, it is preferred to utilize a cap ring 14 as clearly shown in Figure 5 to seal the top of the opening in the body 3. The epo~y material is broughtlevelat 41 with the top of the cap ring 14.
l~ires 17, 18 and 19 connect on the printed circuit board 9 to the conductors 10 and 11 and to the resistor 13 in a manner well kno~n to those skilled in the art.
It should be noted that the split ring 15 is a force fit on the body member 3. This allows easy removal o the split ring 15 for accessa-bility during maintenance.
The types and values of the following components have proved to be satisfactory:
Sensor Head and Heater (3j - Bo~ier PS-1200 Bias Resistor (20) - 110 ohms, 5%, wire wound, 4 watts Heater Control Thermostat ~2) - Stemco, ~ 597 Resistor (22) - 100~ -5%, 1/4 watt, carbon Resistor ~21) - lOK - 5%, 1/4 watt, carbon Diode ~23, 28) - IN4004 - ' - ' ' : , ,: . .
.
;6~
SCR (24) - 2N2323 Resistor ~25) - 47 ohm, 114 watt, carbon Transformer ~30) - Hammond~ 166J25 Relay ~27) - Potter Brumfield, KUP-llA55 Thermostat C5) - Therm-o-Disc, 14T21-L35 Capacitor ~26~ - .12 UF, 250 VDC
Capacitor ~29) .01 UF~ lK VDC
A moisture detection head according to the invention has been con-structed having a size in the order of 4500 cu. mm.
.~ , - . :: ~ ' ~ , . :
This invention relates to a moisture detection head and moisture detection system.
It is known in the prior art to detect moisture by using a sensor head comprisin~ spaced apart ~ires or sets of ~Yires connected to sensing circuitry. If moisture bridges the wires, current ~lo~s between them and is detected by the sensing circuitry. However, some such circuits are only able to detect liquid precipitation, i.e. rain, and are not useful for detect-ing solid precipitation such as snow or freezing rain. In many circumstances, it is hignly desirable to be able to detect solid precipita~ion so that appro-priate action may be taken. ~or example, a railway switch in a remote areacan be rendered inoperative by snow or freezing rain and it is desirable to have means for detecting snow or freezing rain so that an alarm may be given or a heater turned on to keep the switch cleared. Obviously, there are many other situations where such detection is desirable, so as to keep radar, microwave or other communication equipment free of ice.
It is known in the prior art to use a heater resistor so that the sensor head may be warmed to melt snow or ice. However, such a haad has tended to be of large size in order to accommodate a large heater resistor. Further-more, at only moderately low temperatures, the heater resistor may generate far more heat than is actually necessary. The present invention overcomes - these problems and provides a small size sensor head capable of operating over a wide range of low temperatures, e.g. from about the fraezing point down to -40C. The sensor head according to the invention utilizes a small wire wound resistor which, at moderately low temperatures, is connected in series with another, heat dissipating, resistor so that the sensor head does not become unduly warm. Below a certain predetermined temperature~ how-ever, a thermostat closes a switch to bypass the heat dissipating resistor so that full current is supplied to the heater resistor in the sensor head, , g6~
enabling it to operate down to a very low temperature.
Thus, in accordance with one aspect of the invention, there is pro~
vided a moisture detection head comprising first and second lnterleaved, spaced apart, sets of generally parallel conductive wires, said wires each having a generally flat top portion and two downwardly extending end leg portions, the leg portions being secu:red to a printed circuit board, the printed circuit board and sets of wires defining a space in which is secured a wire would heater resistor, the printed circuit board and sets oE wires being contained in a hollow metal body member filled with electrically insul-ating epoxy encapsulating material up to a predetermined level so that the top portions of the wires are exposed, said body member being surrounded by a ring member having a longitudinally extending slot, said ring member extending above and below said predetermined level whereby said ring member provides protection against debris collecting on the exposed top portions of the wires and allows excess water to drain through said slot, said epoxy encapsulating material having a coefficient of thermal expansion substan-tially identical to that of said body member.
.:
.
- ,~
- . , ~ .
. : '' '.' .: -The invention will now be further described in con~unction with the accompanying drawings, in which:
Figure 1 is a block diagram of a system according to the invention for detecting solid precipitation, Figure 2 is a detailed schematic diagram oE a system according to the invention for detecting solid precipitation, Figure 3 is an exploded view of the moisture detection head accord-ing to the invention, Figure 4 is a top view of the moisture detection head according to the invention, and Figure 5 is a cross sectional view along the line A-A of Figure 4.
Referring to Figure 1, the sensor head is indicated at 3 in associa-tion with a heater resistor 13. The power supply 1 is connected to the ~-: heater resistor 13 and to the sensor head 3 through a heater control thermo-stat 2. When moisture is detected by the sensor head 3, current flows from the power supply 1 and this turns on a transistor switch 4 (actually an SCR
in the preferred embodiment) and, if the amblent temperature thermostat 5 is closed, current flows to a relay switch 6 to turn on an alarm 7. Although an alarm is shown in the drawing, it will be obvious that the relay switch 6 could also be used to turn on a heater to melt snow or ice, e.g. on a parking lot, raliway switch, etc.
Referring to Figure 2, the sensor head 3 comprises a grid 12 includ-ing first and second interleaved, spaced apart, sets 10 and 11 of generally parallel conductive wires. Power is applied across the grid 12 by the power supply 1 compris:ing a transformer Tl which, for example, has its primary ~1 :
'' ' ' : ` ~ '. ,` ,`" , ;
.
- . : . .. .
- ~
., 966~31 winding 30 supplied with 120 volts ~C and produces, for example, 27 volts AC at the output of its secondary winding 31. ~ capacitor 29 connected across the secondary 31 serves as a filter.
Referring to Figure 2, the thermostatically controlled switch 2 is normally open, that is, it is open at temperatures above about -12C.
Power is thus applied to wires ll via line 32, resistors 21 and 22 and line l~. Wires 10 connect via line 17 to the other side of the secondary 31 of transformer ~1. If moisture shoulcl bridge the wires 10 and ll, currentwillflow between them and the resulting voltage drop across resistor 21 will be applied through diode 23 to the gate of SCR 24, thus turning it on, assuming thermostat 5 to be closed. Current will thus flow through the SCR 24 and relay 27 to activate the external alarm circuit~
It will be seen that if the temperature drops below -12C, the thermostatically controlled switch 2 will close and bypass the heat dissi-pating resistor 20J thus resulting in increased current flowing to the resis-tor 13 in head 3. This action enables the head 3 to melt snow or ice down to a very low temperature, e.g. -40C. On the other hand, when the tempera-ture is above -12C, the head 3 is not heated to an unnecessary degree.
The inherent resistance of the grid 12 decreases within increasing presence of melted precipitation so that current developed through the series circuit of the grid 12 and resistors 21 and 22 increases with a constant voltage until the grid is completely inundated with water. The values of resistors 21 and 22 are calibrated against the changing series resistance of the grid 12 to produce a voltage drop across resistor 21 of sufficient level to trigger the SCR 24 into conduction. Diode 23 serves as a coupler as wel]. as rectifying the supply voltage in order to satisfy the direct current t:rigger requirements of the SCR 24.
When the S(:R 24 is triggered into conduction, alternating current - ' ':
-present on the cathode is rectified as it passes through to the anode thusenergi~in~ ti~e relay switch 27. Resistor 25 and capacitor 26 together serve as a line filter to protect the SCR from transient line surges. Diode 28 rectifies any chatter produced by the contacts of relay 27. In operation, when the voltage level at the output of the voltage divider and rectifier rèaches a ~iven value, the alarm will be activated providing the ambient temperature thermostat 5 is closedJ indicating that an undesirable form of precipitation is imminent. Thermostat 5 opens above about -~2C so that the alarm is not activated if the precipitation is simply rain. That is, the alarm is unnecessary when the ambient temperature is above the freezing point.
Referring to Figure 3, the moisture detection head is seen to com-prise first and second interleaved, spaced apart, sets of generally parallel conductive wires 10 and 11, the wires each having a generally flat top por-tion and two downwardly extending end leg portions. The leg portions are secured to a printed circuit board 9, the printed circuit board and sets of wires defining a space in which is secured a wire wo~md heater resistor 13. A wire wound resistor is used because it is capable of prod~lcing suf-ficient heat while being relatively small in size.
The printed circuit board 9 and sets of wires are contained in a hollow metal body member 3 filled with electrically insulating epoxy encap-; sulating material 16 ~Figure 4) up to a predetermined level so that the top portions of the wires 10 and 11 are exposed~ The body member is surrounded by a ring member 15 having a longitudinally extending slot 40, the ring member 15 extending abcve and below the predetermined level 41 ~Figure 5) whereby the ring member provides protection against foreign materials collecting on the exposed portions of the wires and allows excess water to drain through the slot 40.
The epoxy encapsulating material, which fills the body 3 up to level ; .
- ': . : , - , , .
, . , . ''' . - , . , ~ ' -~
' - '.
966~
41, is selected to have a coefficient o thermal expansion substantially identical to that of the body member 3. This is so that the sensor head may operate over a wide range of temperatures without the encapsulating material pulling away from the body member 3. The body member 3 is prefer-ably of brass, in which case the encapsulating material preferred is that sold under the trade mark Stycast Epoxy Casting Resin by Emerson-Cuming of Canton, ~lassachusetts. This is a high thermal K resin. The Epoxy Casting Resin used is Stycast 2850-FT and the hardner is catalyst number 11.
The ~ires 10 and 11 are preferably of gold clad stainless steel for good electrical and heat conductivity and resistance to corrosion.
Preferably the printed circuit board 9 sits on a fiber washer 8 within the body 3. Also, it is preferred to utilize a cap ring 14 as clearly shown in Figure 5 to seal the top of the opening in the body 3. The epo~y material is broughtlevelat 41 with the top of the cap ring 14.
l~ires 17, 18 and 19 connect on the printed circuit board 9 to the conductors 10 and 11 and to the resistor 13 in a manner well kno~n to those skilled in the art.
It should be noted that the split ring 15 is a force fit on the body member 3. This allows easy removal o the split ring 15 for accessa-bility during maintenance.
The types and values of the following components have proved to be satisfactory:
Sensor Head and Heater (3j - Bo~ier PS-1200 Bias Resistor (20) - 110 ohms, 5%, wire wound, 4 watts Heater Control Thermostat ~2) - Stemco, ~ 597 Resistor (22) - 100~ -5%, 1/4 watt, carbon Resistor ~21) - lOK - 5%, 1/4 watt, carbon Diode ~23, 28) - IN4004 - ' - ' ' : , ,: . .
.
;6~
SCR (24) - 2N2323 Resistor ~25) - 47 ohm, 114 watt, carbon Transformer ~30) - Hammond~ 166J25 Relay ~27) - Potter Brumfield, KUP-llA55 Thermostat C5) - Therm-o-Disc, 14T21-L35 Capacitor ~26~ - .12 UF, 250 VDC
Capacitor ~29) .01 UF~ lK VDC
A moisture detection head according to the invention has been con-structed having a size in the order of 4500 cu. mm.
.~ , - . :: ~ ' ~ , . :
Claims (5)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A moisture detection head comprising first and second interleaved, spaced apart, sets of generally parallel conductive wires, said wires each having a generally flat top portion and two downwardly extending end leg portions, the leg portions being secured to a printed circuit board, the printed circuit board and sets of wires defining a space in which is secured a wire wound heater resistor, the printed circuit board and sets of wires being contained in a hollow metal body member filled with electrically insulating epoxy encapsulating material up to a predetermined level so that the top portions of the wires are exposed, said body member being surrounded by a ring member having a longitudinally extending slot, said ring member extending above and below said predetermined level whereby said ring member provides protection against foreign material collecting on the exposed top portions of the wires and allows excess water to drain through said slot, said epoxy encapsulating material having a coefficient of thermal expansion substantially identical to that of said body member.
2. A moisture detection head as claimed in claim 1 and further compris-ing a cap ring secured in said body member by said encapsulating material, said ring having a top surface substantially flush with said predetermined level of encapsulating material.
3. A moisture detection head as claimed in claim 2 wherein said printed circuit board rests on a fiber washer in said body member.
4. A moisture detection head as claimed in claim 3 wherein said first and second sets of wires are connected to first and second terminals on said printed circuit board and said heater resistor is connected between a third terminal on said printed circuit board and one of said first and second terminals.
5. A moisture detection head as claimed in claim 1, 2 or 3 wherein said body member is brass.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000314381A CA1119669A (en) | 1978-10-26 | 1978-10-26 | Precipitation detection system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000314381A CA1119669A (en) | 1978-10-26 | 1978-10-26 | Precipitation detection system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1119669A true CA1119669A (en) | 1982-03-09 |
Family
ID=4112703
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000314381A Expired CA1119669A (en) | 1978-10-26 | 1978-10-26 | Precipitation detection system |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1119669A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0507283A1 (en) * | 1991-04-02 | 1992-10-07 | Sumitomo Electric Industries, Limited | High-temperature superconducting coil and method of manufacturing thereof |
| WO1995023985A1 (en) * | 1994-03-04 | 1995-09-08 | Rosemount Aerospace Limited | Snow presence detection |
| EP0746779A1 (en) * | 1992-09-04 | 1996-12-11 | The B.F. Goodrich Company | Snow sensor |
-
1978
- 1978-10-26 CA CA000314381A patent/CA1119669A/en not_active Expired
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0507283A1 (en) * | 1991-04-02 | 1992-10-07 | Sumitomo Electric Industries, Limited | High-temperature superconducting coil and method of manufacturing thereof |
| AU654339B2 (en) * | 1991-04-02 | 1994-11-03 | Sumitomo Electric Industries, Ltd. | High temperature superconducting coil and method of manufacturing thereof |
| US5512867A (en) * | 1991-04-02 | 1996-04-30 | Sumitomo Electric Industries, Ltd. | High temperature superconducting coil and method of manufacturing thereof |
| EP0746779A1 (en) * | 1992-09-04 | 1996-12-11 | The B.F. Goodrich Company | Snow sensor |
| EP0746779A4 (en) * | 1992-09-04 | 1997-05-07 | Rosemount Inc | Snow sensor |
| WO1995023985A1 (en) * | 1994-03-04 | 1995-09-08 | Rosemount Aerospace Limited | Snow presence detection |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |