CA1090860A - Electric pipe thawing apparatus with current sensing means - Google Patents
Electric pipe thawing apparatus with current sensing meansInfo
- Publication number
- CA1090860A CA1090860A CA269,414A CA269414A CA1090860A CA 1090860 A CA1090860 A CA 1090860A CA 269414 A CA269414 A CA 269414A CA 1090860 A CA1090860 A CA 1090860A
- Authority
- CA
- Canada
- Prior art keywords
- terminals
- current
- pair
- warning means
- current sensing
- 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
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/08—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current
-
- E—FIXED CONSTRUCTIONS
- E03—WATER SUPPLY; SEWERAGE
- E03B—INSTALLATIONS OR METHODS FOR OBTAINING, COLLECTING, OR DISTRIBUTING WATER
- E03B7/00—Water main or service pipe systems
- E03B7/09—Component parts or accessories
- E03B7/14—Devices for thawing frozen pipes
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
- F16L53/00—Heating of pipes or pipe systems; Cooling of pipes or pipe systems
- F16L53/30—Heating of pipes or pipe systems
- F16L53/35—Ohmic-resistance heating
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Public Health (AREA)
- Water Supply & Treatment (AREA)
- Mechanical Engineering (AREA)
- Freezing, Cooling And Drying Of Foods (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
Apparatus for heating pipes and particularly for thawing frozen pipes is disclosed. The apparatus may be a self contained trailer having a generator and step-down transformer. One pair of terminals is connected to the secondary of the transformer and a pair of bus bars is also connected across the secondary. A current transformer operates a warning system indicating that the current to the first terminals is above a maximum value.
This warns the operator that another pair of cables is necessary to heat effectively the pipe.
Apparatus for heating pipes and particularly for thawing frozen pipes is disclosed. The apparatus may be a self contained trailer having a generator and step-down transformer. One pair of terminals is connected to the secondary of the transformer and a pair of bus bars is also connected across the secondary. A current transformer operates a warning system indicating that the current to the first terminals is above a maximum value.
This warns the operator that another pair of cables is necessary to heat effectively the pipe.
Description
~`3(~8t;0 This invention relates to an improved appratus for electrically heating pipes and particularly thawing frozen pipes, hydrants, electric cable ducts and the like.
Such apparatus is known which comprises a movable trailer incor-porating a generator, a step-down transformer and two bus bars to which electric cables can be connected. Each bus bar is arranged to accept several cables, one or more cables of one bus bar being connected to one end of a pipe (or pipe system) to be thawed and one or more cables of the other bus bar being connected to the other end of the pipe to be thawed.
One problem with the known apparatus is due to the fact that the operators generally have little knowledge of electrical theory. They con-nect up one pair of cables and run the machine at a current output of around 200 amps. If, after 10 minutes or so there is no evidence of thawing they simply increase the current as i* seems logical that will bring about the desired result. T~ey do not think it necessary to add more cables, which is time-consuming, when one pair of cables evidently can carry easily the increased current. This is because they do not appreciate that the resistance of the cables themselves is an important ~actor especially where the pipe is copper which has a very low resistance. In this case the I~R heat generated in the cables will increase at a greater rate than the I2R heat generated in the pipe and what is required is a reduction in the cable resistance which can only be accomplished by adding cables in parallel.
The extra high voltage which can arise when there is a temporary open circuit can cause an arc which is a serious fire hazard.
According to the present invention there is provided apparatus for heating pipes electrically, comprising, a first pair of terminals connect~
ible to a source of power, at least one other pair of terminals connect-ible to the source of power in parallel with first pair of terminals, current sensing means connected to sense the current flowing in at least one of the terminals of the first pair of terminals, and warnlng means ~)9~
operated by the current sensing means when the current sensing ~eans senses a current in excess of a predetermined value.
The invention will now be described in greater detail with refer-ence to the accompanying drawings the single figure of which is a diagram-matic view of a pipe thawing machine embodying the invention.
The apparatus includes a step-down transformer 1 having a primary coil 2 and a secondary coil 3. The primary coil 2 is wound to accept the H.V. output of a diesel generator (not shown), and is tapped so that the voltage derived on the secondary coil 3 may be varied up to a maximum of 45 volts, the current in the coil 3 being up to 1500 amperes.
Each end of secondary coil 3 is connected to a terminal 4 and 5, respectively, which are each formed with a projecting stud receiving a connector 6 and 7, respectively connected to an end of a flexible cable 8 and a flexible cable 9.
. The other end of cable 8 is provided with a suitable connector, such as a screw-clamp connector 12 for connecting the cable to a water tap 13 defining one end of the pipe system 14 to be thawed. The other end of cable 9 is also provided with a screw-clamp 15 for connecting the cable 9 to a hydrant 16 defining the other end of the pipe system to be thawed.
Each end of secondary coil 3 is also connected to a respective bus 18 or 19. Each bus 18 or 19 is formed with one or more, four in this embodiment, studs 20 identical to the studs of terminals 4 and 5. It should be clear that up to four more flexible cables similar to the cables 8 and 9 may be connected from each bus 18 or 19 to the tap ]3 and the hydrant 16, respectively, in the same way that the cables 8 and 9 are connected.
As an example, the first stud of bus 18 is shown connected to the tap 13 b~y a dotted line 2Z representing a flexible cable connection and the first stud of bus 19 is shown connected to the hydrant 13 by a dotted line 23 also representing a flexible cable.
It can be seen that each end of the secondary 3 is branched forming two branches 24 and 25 ~and 24' and 25') at each end, these branches forming the connection between the secondary and the terminal 4 and bus 18 ~an~
terminal 5 and bus 19).
A current transformer 26 ~26') is received on each branch 24 (24') and the output of the current transformer is connected as the input of a relay 27 (27') arranged to operate at a voltage corresponding to a current of 250 amps in the branch 24 (24'). Actuation of the relay 27 (27') causes energisation of a warning light or flasher 28 (28') and/or an audible signal.
The apparatus described above is preferable incorporated in a self-contained unit which may be towed to She site at which pipe thawing is to be carried out. The unit houses the diesel electric generator, step-down transformer, current transformers and relays. The terminals 4 and 5 and the busses 18 and 19 are mounted on end of the housing in the configuration shown and the flashers 28 and 28' are mounted adjacent the respective terminals 4 and 5.
In operation, with the unit at the loca~ion of the frozen yipe, the operator attaches cables 8 and 9 as shown and runs the generator with the primary tap adjusted to give a current output of less than 250 amps.
This current flows through the G~ent comprising the secondary 3, cable 8, connector ~, tap 13, pipe 14, hydrant 16, connector 15 and cable 9.
The I R heat losses in the tap 13, pipe 14 and hydrant 16 tend to thaw the Sap, pipe or hydrant as the case may be be. If after some 10 minutes or so there is no evidence that the thawing is effective it is obvious that the I R loss is insufficient and greater current flow is necessary.
If the operator simply increases the current output the flashers 28 and 28' will operate at the 250 amp level warning him that at least one more pair of cables is needed. The operator will, therefore, add the cables indicated by the dotted lines and crank up the generator until the current output in the secondary is considerably above 250 amps, possibly as high ~)90~
~ soo as ~0 amps.
It may be found necessary to increase the current still further to effect thawing and this may be done providing that sufficient cables are added to ensure that the flashers 29 and 28' are extinguished.
It is envisaged that the invention need not incorporate a generator as the necessary power may be drawn direc~ly from the electrical power company supply.
The apparatus according to the invention may also be provided Wit}
an additional warning light or buzzer on the actual control panel which is remote from the bus bars.
The apparatus of the invention may additionally be provided with automatic tripping means in the form of a circuit breaker energised by the current transformer 26, for example, to break the supply from the secondary winding 3 if the current exceeds a predetermined value - 350 amps for example.
Such apparatus is known which comprises a movable trailer incor-porating a generator, a step-down transformer and two bus bars to which electric cables can be connected. Each bus bar is arranged to accept several cables, one or more cables of one bus bar being connected to one end of a pipe (or pipe system) to be thawed and one or more cables of the other bus bar being connected to the other end of the pipe to be thawed.
One problem with the known apparatus is due to the fact that the operators generally have little knowledge of electrical theory. They con-nect up one pair of cables and run the machine at a current output of around 200 amps. If, after 10 minutes or so there is no evidence of thawing they simply increase the current as i* seems logical that will bring about the desired result. T~ey do not think it necessary to add more cables, which is time-consuming, when one pair of cables evidently can carry easily the increased current. This is because they do not appreciate that the resistance of the cables themselves is an important ~actor especially where the pipe is copper which has a very low resistance. In this case the I~R heat generated in the cables will increase at a greater rate than the I2R heat generated in the pipe and what is required is a reduction in the cable resistance which can only be accomplished by adding cables in parallel.
The extra high voltage which can arise when there is a temporary open circuit can cause an arc which is a serious fire hazard.
According to the present invention there is provided apparatus for heating pipes electrically, comprising, a first pair of terminals connect~
ible to a source of power, at least one other pair of terminals connect-ible to the source of power in parallel with first pair of terminals, current sensing means connected to sense the current flowing in at least one of the terminals of the first pair of terminals, and warnlng means ~)9~
operated by the current sensing means when the current sensing ~eans senses a current in excess of a predetermined value.
The invention will now be described in greater detail with refer-ence to the accompanying drawings the single figure of which is a diagram-matic view of a pipe thawing machine embodying the invention.
The apparatus includes a step-down transformer 1 having a primary coil 2 and a secondary coil 3. The primary coil 2 is wound to accept the H.V. output of a diesel generator (not shown), and is tapped so that the voltage derived on the secondary coil 3 may be varied up to a maximum of 45 volts, the current in the coil 3 being up to 1500 amperes.
Each end of secondary coil 3 is connected to a terminal 4 and 5, respectively, which are each formed with a projecting stud receiving a connector 6 and 7, respectively connected to an end of a flexible cable 8 and a flexible cable 9.
. The other end of cable 8 is provided with a suitable connector, such as a screw-clamp connector 12 for connecting the cable to a water tap 13 defining one end of the pipe system 14 to be thawed. The other end of cable 9 is also provided with a screw-clamp 15 for connecting the cable 9 to a hydrant 16 defining the other end of the pipe system to be thawed.
Each end of secondary coil 3 is also connected to a respective bus 18 or 19. Each bus 18 or 19 is formed with one or more, four in this embodiment, studs 20 identical to the studs of terminals 4 and 5. It should be clear that up to four more flexible cables similar to the cables 8 and 9 may be connected from each bus 18 or 19 to the tap ]3 and the hydrant 16, respectively, in the same way that the cables 8 and 9 are connected.
As an example, the first stud of bus 18 is shown connected to the tap 13 b~y a dotted line 2Z representing a flexible cable connection and the first stud of bus 19 is shown connected to the hydrant 13 by a dotted line 23 also representing a flexible cable.
It can be seen that each end of the secondary 3 is branched forming two branches 24 and 25 ~and 24' and 25') at each end, these branches forming the connection between the secondary and the terminal 4 and bus 18 ~an~
terminal 5 and bus 19).
A current transformer 26 ~26') is received on each branch 24 (24') and the output of the current transformer is connected as the input of a relay 27 (27') arranged to operate at a voltage corresponding to a current of 250 amps in the branch 24 (24'). Actuation of the relay 27 (27') causes energisation of a warning light or flasher 28 (28') and/or an audible signal.
The apparatus described above is preferable incorporated in a self-contained unit which may be towed to She site at which pipe thawing is to be carried out. The unit houses the diesel electric generator, step-down transformer, current transformers and relays. The terminals 4 and 5 and the busses 18 and 19 are mounted on end of the housing in the configuration shown and the flashers 28 and 28' are mounted adjacent the respective terminals 4 and 5.
In operation, with the unit at the loca~ion of the frozen yipe, the operator attaches cables 8 and 9 as shown and runs the generator with the primary tap adjusted to give a current output of less than 250 amps.
This current flows through the G~ent comprising the secondary 3, cable 8, connector ~, tap 13, pipe 14, hydrant 16, connector 15 and cable 9.
The I R heat losses in the tap 13, pipe 14 and hydrant 16 tend to thaw the Sap, pipe or hydrant as the case may be be. If after some 10 minutes or so there is no evidence that the thawing is effective it is obvious that the I R loss is insufficient and greater current flow is necessary.
If the operator simply increases the current output the flashers 28 and 28' will operate at the 250 amp level warning him that at least one more pair of cables is needed. The operator will, therefore, add the cables indicated by the dotted lines and crank up the generator until the current output in the secondary is considerably above 250 amps, possibly as high ~)90~
~ soo as ~0 amps.
It may be found necessary to increase the current still further to effect thawing and this may be done providing that sufficient cables are added to ensure that the flashers 29 and 28' are extinguished.
It is envisaged that the invention need not incorporate a generator as the necessary power may be drawn direc~ly from the electrical power company supply.
The apparatus according to the invention may also be provided Wit}
an additional warning light or buzzer on the actual control panel which is remote from the bus bars.
The apparatus of the invention may additionally be provided with automatic tripping means in the form of a circuit breaker energised by the current transformer 26, for example, to break the supply from the secondary winding 3 if the current exceeds a predetermined value - 350 amps for example.
Claims (12)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. Apparatus for heating pipes electrically, comprising a source of low voltage high current power, means for varying the current, a first pair of terminals connected across the source of power, at least one other pair of terminals connected across the source of power in parallel with first pair of terminals, current sensing means connected to sense the current flowing in at least one of the terminals of the first pair of terminals, and warning means operated by the current sensing means when the current sensing means senses a current in excess of a predetermined value.
2. Apparatus according to claim 1 in which the at least one other pair of terminals is formed on a pair of bus bars each having a plurality of terminals.
3. Apparatus according to claim 2 in which there is a further current sensing means connected to sense the current flowing in the other terminal of the first pair of terminals and further warning means operated by the further current sensing means when the further current sensing means senses a current in excess of a predetermined value.
4. Apparatus according to claim 1 or claim 2 in which the warning means is a visual warning means.
5. Apparatus according to claim 1 or claim 2 in which the warning means is an audio warning means.
6. Apparatus according to claim 3 in which the further warning means is a visual warning means.
7. Apparatus according to claim 3 in which the further warning means is an audio warning means.
8. Apparatus according to claim 1 in which the current sensing means is a current transformer.
9. Apparatus according to claim 8 in which the current transformer is connected to a relay operable to energise the warning means.
10. Apparatus according to claim 3 in which the warning means and the further warning means comprise, respectively, first visual warning means and second visual warning means, the first visual warning means being located physically adjacent one of the first pair of terminals and one of the bus bars and the second visual warning means being located physically adjacent the other of the first pair of terminals and the other bus bar.
11. Apparatus for heating pipes electrically, comprising a first pair of terminals connectible to a source of power, at least one other pair of terminals connectible to the source of power in parallel with the first pair of terminals, current sensing means connected to sense the current flowing in at least one of the terminals of the first pair of terminals, and warning means operated by the current sensing means when the current sensing means senses a current in excess of a predetermined value.
12. Apparatus according to claim 1, 2 or 3, including automatic tripping means energisable by the current sensing means to interrupt the power supply when the current exceeds a predetermined value.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA269,414A CA1090860A (en) | 1977-01-10 | 1977-01-10 | Electric pipe thawing apparatus with current sensing means |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA269,414A CA1090860A (en) | 1977-01-10 | 1977-01-10 | Electric pipe thawing apparatus with current sensing means |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1090860A true CA1090860A (en) | 1980-12-02 |
Family
ID=4107698
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA269,414A Expired CA1090860A (en) | 1977-01-10 | 1977-01-10 | Electric pipe thawing apparatus with current sensing means |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1090860A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113463728A (en) * | 2021-07-13 | 2021-10-01 | 浙江融乐环境科技有限公司 | Constant pressure water supply equipment with emergency function |
-
1977
- 1977-01-10 CA CA269,414A patent/CA1090860A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113463728A (en) * | 2021-07-13 | 2021-10-01 | 浙江融乐环境科技有限公司 | Constant pressure water supply equipment with emergency function |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |