US3210952A

US3210952A - Reclamation device for gas-type circuit interrupters

Info

Publication number: US3210952A
Application number: US159821A
Authority: US
Inventors: Albert P Strom
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1961-12-11
Filing date: 1961-12-11
Publication date: 1965-10-12
Anticipated expiration: 1982-10-12

Description

Oct. 12, 1965 A. P. STROM 3,210,952

REGLAMATION DEVICE FOR GAS-TYPE CIRCUIT INTERRUPTERS Original Filed Dec. 9, 1958 2 Sheets-Sheet 1 Vapor Pressure of Sulfur Hexafluoride at very low Temperatures Temperature of CO Ice at l Arm.

lMillime'er at |33 WITNESSES I4O l20 -IOO -80 60 Temperature C i mvsuron Al berf P. Sfrom ATTORN EY Oct. 12, 1965 A. P. STRQM 3,210,952

RECLAMATION DEVICE FOR GAS-TYPE CIRCUIT INTERRUPTERS Original Filed Dec. 9, 1958 2 Sheets-Sheet 2 v 23.. 53 u a: w E

I5 20 Vacuum g? I Q .v

46 L 2 Q I 44 v M Q United States Patent 3,210,952 RECLAMATION DEVICE FOR GAS-TYPE CIRCUIT INTERRUPTERS Albert P. Strom, Forest Hills, Pa., assignor to Westinghouse Electric Corporation, Pittsburgh, Pa., a corporation of Pennsylvania Continuation of application Ser. No. 779,103, Dec. 9, 1958. This application Dec. 11, 1961, Ser. No. 159,821

5 Claims. (Cl. 62-40) This application is a continuation of my patent application filed December 9, 1958, Serial No. 779,103 and now abandoned.

This invention relates to reclamation devices for gastype circuit interrupters, and, more particularly, to a liquefaction-type reclamation device for collecting and liquefying gas from gas-type circuit interrupters during .the maintenance thereof.

As well known by those skilled in the art, it is advisable periodically to open circuit interrupters, inspect the contact structures thereof and to make necessary adjustments as well as replace worn parts. In the case of a .gas-type circuit interrupter, when this maintenance operation takes place and the casing enclosing the arc-extinguishing gas is opened for such inspection purposes, a decision must be made as to whether the enclosed gas used for arcextinguishing purposes is to be freely dissipated to the atmosphere, and hence lost, resulting in the necessity for a fresh charge of arc-extinguishing gas during the subsequent return of the circuit interrupter into operation, or whether the arc-extinguishing gas is to be collected and reclaimed during this inspecting operation.

The aforesaid decision may hinge on economics, and if the arc-extinguishing gas used in the gas-type circuit interrupter -is sufi'iciently expensive, and if the volume and pressure of the arc-extinguishing gas is considerable, it is advisable to provide apparatus for effecting the collection and reclamation of the arc-extinguishing gas, so that it may subsequently be used in the same or similar circuit interrupters when such circuit interrupters are returned to active duty on the transmission system.

It is a general object of the present invention to provide an improved, portable, reclamation device suitable for the connection to gas-type circuit interrupters so that the gas from the circuit interrupter may be collected and stored within the reclamation device.

A more specific object of the present invention is to provide an improved reclamation device suitable for the detachable connection to a gas-type circuit interrupter, in which gas from the circuit interrupter may be collected and liquefied by suitable cooling and condensing means so that the resulting liquefied arc-extinguishing gas may .be collected in a storage tank associated with the aforesaid reclamation device for subsequent use in the same or similar gas-type circuit interrupters.

A further object of the invention is to provide an improved reclamation device having associated therewith a condensing chamber, within which is disposed a suitable condensing coil and having means provided for effecting Patented Oct. 12, 1965 ice proved reclamation device suitable for collecting and liquefying arc-extinguishing gas from a circuit interrupter during periodic maintenance inspection periods, in which two coolant agents are employed in the condensing coil of the reclamation device to save expense of operation.

Further objects and advantages will readily become apparent upon reading the following specification, taken in conjunction with the drawings, in which:

FIGURE 1 is a curve of the vapor pressure of sulfur hexafluoride at very low temperatures; and

FIG. 2 illustrates in vertical cross-section, and partially diagrammatic, the reclamation device of the present invention associated with a circuit interrupter of the gastype.

As well known by those skilled in the art, particularly in recent years, investigations have resulted in the determination of the extremely high interrupting performance of certain arc-extinguishing gases. Sulfur hexafluoride (SP is such a gas and is relatively expensive. The properties of sulfur hexafluoride for circuit interruption are set out in detail in United States Patent 2,757,261, issued July 31, 1956 to Harry I. Lingal, Thomas E. Browne, In, and Albert P. Strom, and assigned to the assignee of the instant application. The use of sulfur hexafluoride for circuit interruption has been extensive, being employed for circuit interrupters of the load-break disconnecting switch type, such as illustrated in United States Patent 2,769,063, issued October 30, 1956, to Harry J. Lingal, and assigned to the assignee of the instant application. In addition, sulfur hexafluoride has been used in connec tion with power interrupters, such as set out in United States Patent 2,748,226, issued May 29, 1956, to John B. MacNeill and Benjamin P. Baker, and likewise assigned to the assignee of the instant application.

Selenium hexafiuoride (SeF is also a very powerful arc-extinguishing gas and is likewise expensive. It is described and claimed in United States Patent 2,733,316, issued January 31, 1956, to Thomas E. Browne, Jr., Albert P. Strom and Harvey E. Spindle, and assigned to the assignee of the instant application.

Although the present invention is suitable for use with a number of arc-extinguishing gases, for purposes of simplicity and clarification of the invention, the invention will be described as particularly applied to a circuit interrupter employing sulfur hexafluoride (SF gas as the arcextinguishing medium, without any intention of limiting the broader aspects of the invention to this particular gas.

Sulfur hexafluoride gas has been shown to be an excellent circuit interrupting medium, as set out in United States Patent 2,757,261, and is already being used for this purpose in many recently developed commercial circuit interrupters. It is a relatively expensive gas at present, the present price being $2.25 per pound of gas, or about 10 per gallon per atmosphere. Since the gas pressure normally used in the circuit breakers is about 4 or 5 atmospheres, the cost of filling an SP breaker is about 40 to 50 per gallon, or somewhat more than for an oil circuit breaker of equal volume. This makes it rather desirable to save and to reclaim this gas when a breaker is to be opened for servicing.

The sulfur hexafluoride gas could be drawn by a compressor out of the breaker down to about atmospheric pressure, and subsequently compressed into a storage cylinder. To remove the gas to a pressure below that of atmospheric pressure, a vacuum pump would have to be used in series with the compressor. If the gas is pumped into the storage cylinder at normal temperature, it will be necessary to compress the gas to about 350-400 p.s.i. This consequently requires relatively expensive compressing equipment, as well as the use of a vacuum pump.

It is proposed in the present invention, however, to

provide a method and means whereby the SP gas may be removed from the breakers and collected in a storage cylinder, which is much more convenient and considerably less expensive. The proposed method of the present invention is that of freezing out the sulfur hexafiuoride gas by the use of carbon dioxide ice or with liquid nitrogen, or, in fact, utilizing both coolant agents in sequence.

The vapor pressure curve for sulfur hexafluoride (SP at temperatures below those for liquefaction at atmospheric pressure is illustrated in FIG. 1. This curve shows that at point A, namely substantially at 78 C., the temperature of Dry Ice, the vapor pressure of SP is about 300 millimeters, or approximately 0.4 atmosphere. It is thus possible to reduce the pressure in a sulfur hexafiuoride gas-type breaker to 0.4 atmosphere, by simply cooling the gas storage cylinder connected to the breaker volume with Dry Ice, or solid carbon dioxide.

The cost, at present, of Dry Ice or solid carbon dioxide, is only about 4 per pound. The cooling effect may be calculated as follows:

The latent heat of vaporization of CO is about 80 calories per gram at 78 C. Hence, a pound of evaporating CO absorbs about 80x454=36,000 calories. The latent heat of vaporization of SP is about 35 calories per gram. The specific heat (Cp) is about 0.2 calorie/ gram/degree. Hence, to cool and to condense one pound of SE, from 20 to 78 C., requires approximately (0.2 98+35) 454=24,500 calories.

Thus, neglecting heat losses, one pound of SP can be cooled to -78 C., and condensed with about at a cost of 0.68 4=2.75 cents.

It is of interest to note that in a particular 3-pole, 115 kv., SP breaker, a total of about 24 pounds of SP gas will be used at atmospheric pressure. If this is removed and saved down to 0.4 atmosphere by means of Dry Ice, 90% of the SP gas, or 21.6 pounds can be recovered. The cost, assuming 50% efficiency, would be There would still be about 2.4 pounds of SP gas left in the breaker worth approximately $4.80, which could not be salvaged.

However, if liquid nitrogen (N is used instead of Dry Ice, a temperature of l95 C. can be reached. At

=0.68 pounds of Dry Ice this temperature, the pressure of SE, will be in the order =l.7 pounds of liquid nitrogen The density of liquid nitrogen is 0.808, or weight per liter 808 grams 1.78 pounds.

It thus appears that about 1 liter of liquid nitrogen is required to condense 1 pound of SP The cost of liquid nitrogen per liter is about 15. Hence, the total cost to condense the 24 pounds of gas in the breaker discussed above would be 15 24=$3.60, neglecting heat losses or $7.20, assuming 50% efiiciency. Thus, while the cost per pound of condensed SP is less with Dry Ice, when the cost of the SP which cannot be salvaged is included,

4 it appears as if the net cost for either Dry Ice or liquid nitrogen might be about equal.

The foregoing calculations indicate that with suitable equipment involving proper heat exchangers, it is quite practical to use freeze out methods for recovering or reclaiming SP gas from circuit breakers, and, more importantly, in many cases it saves the investment in expensive compressor equipment.

With the foregoing principles in mind, there will now be described an improved circuit interrupter having associated therewith a condensable cooling means generally designated by the reference numeral 1 in FIG. 2 of the drawings. With reference to FIG. 2, it will be noted that the condensable cooling means 1, or portable reclamation device, includes a condensing chamber 2 having an inlet 3 leading from a detachable connection 4 to a gastype circuit interrupter, generally designated by the reference numeral 5.

Generally, the circuit interrupter 5 contains a relatively expensive arc-extinguishing gas 6, which may be SP SCFG, CO2, CF3B1', CZFG, SOFZ, CCIFQ, C2ClF3, S02, C 1 OCI F C1031: or CF SF Disposed interiorly within a casing 7 of the circuit interrupter 5 is a relatively stationary contact 8, which cooperates with a movable contact 9, the latter being associated with a piston structure 10 and withdrawn upwardly, during the opening operation, by a conductor operating rod 11. A terminal 12 is associated with the upper end of the conducting operating rod 11. An additional terminal 13 is connected to the base 14 of the relatively stationary contact 8. An apertured metallic piston plate 15 is threadedly secured to the lower extremity of the conducting operating rod 11. The outer periphery of the piston plate 15 is preferably threadedly secured to the upper end of a piston sleeve 16, the latter supporting a movable orifice structure 17 therewith. The details of construction of the piston structure 10 are more fully set out and claimed in United States Patent 2,757,261 referred to hereinbefore.

For the purpose of understanding the present invention, it is only necessary to know that the operating rod 11 moves upwardly during the opening operation through a gas-tight seal 18 causing the separation between the lower end of the movable contact 9 and the stationary contact 8. This, of course, establishes an arc therebetween interiorly of the sealed casing 7. Since the apertured piston plate 15 is secured to, and movable with, the lower end of operating rod 11, it will be apparent that the orifice structure 17 is carried upwardly during the opening operation.

The arc-extinguishing condensable gas 6, disposed within the region 19 in back of the piston structure 10, will be forced through the apertures 20 in apertured piston plate 15 and through the orifice 21 associated with the orifice structure 17, causing thereby a longitudinal compressed flow of gas 6 adjacent the established arc between contacts 8, 9 effecting the rapid extinction thereof. The circuit between the terminals 12, 13 will then be broken.

Communicatnig with the upper end of the casing 7 of the circuit interrupter 5 is a gas conduit 22. A bore 23 through a guide sleeve 24 insures communication between the conduit 22 and the interior 19 of the casing 7.

Preferably, a cutoff valve 25 is provided, so that when the casing 7 is charged with a suitable condensable arcextinguishing gas 6, the valve 25 may be closed and the circuit interrupter 5 will then be adapted for independent operation.

As stated hereinbefore, however, it periodically becomes necessary to maintain, or service the gas-type circuit interrupter 5, and when this is done, the casing 7 will be opened for inspection purposes. To prevent the loss of the relatively expensive arc-extinguishing gas 6, the condensable cooling means 1 is provided. As shown in FIG. 2, a coupling 26 detachably interconnects the exhaust tube 4 with the gas conduit 22. In addition, a second coupling 28 detachably interconnects the exhaust tube 4 with an inlet tube or inlet pipe means 29 leading to the inlet 3 of reclaiming device 1. The inlet tube 29 is of T-shaped configuration having a branch conduit 30 leading, through a cutoif valve 31, to a source of vacuum, not shown. The branch conduit 30 and the cutolf valve 31 constitute a valve-controlled vacuum-pipe means, generally designated by the reference numeral 60.

The upper end of the condensing chamber 2 is controlled by a valve 32. The valve 32 is provided for closing the passage from the gas chamber or casing 7 of circuit interrupter 5 to the condensing chamber 2. A condensing coil 33 extends from the bottom of condensing chamber 2 into the interior thereof, and for ease of manufacture and assembly, the condensing coil 33 is shown as attached to a plate 34, which is bolted, by bolts 35 to chamber 2. Preferably, a gasket 36 is employed to provide a gas tight connection. Thus, the plate 34 forms the bottom of the condensing chamber 2.

Connections for the condensing coil 33 are brought out at 37, 38. A container cup 39 is provided to hold the-cooling fluid. If carbon dioxide ice is used, a low freezing point liquid, such as acetone or alcohol, can be used with 'it as a heat transfer liquid. A screen 40 prevents any solid particles from entering the condensing coil33. The coolant liquid 41 then passes through the pump, 42, into tube 37, through condensing coil 33, through tube 38 and tube 43 back to the cup 39. If the pump means 42 is not available, the coolant liquid may be circulated through the coils 33 by opening valve 44, collecting the liquid in storage tank 45 and pouring it back manually into the reservoir chamber, or container cup 39.

With a solid carbon dioxide and acetone system, it should be possible to cool the coils 33 to about -78 C. This will condense the sulfur hexafluoride (SP to about 0.3 or 0.4 atmosphere. The pressure within condensing chamber 2 will then fall to less than 1 atmosphere, and consequently, the gas from the casing 7 of circuit inter-. rupter 5 will be drawn into the condensing chamber 2 and liquefied. One difficulty, however, is that in the case of SF gas, it has a melting point of 56 C., which is reached at slightly above atmospheric pressure, and as the pressure in condensing chamber 2 falls to below atmospheric pressure, the SE; gas may condense as a solid on the cooling coil 33. This might tend to heat insulate the cooling coils 33, greatly reducing the rate of condensation of SF gas.

However, to de-ice the coils 33, it is necessary only to raise the temperature to '56 C. For such a de-icing operation, a heating element 61 comprising a heater coil 46 is provided. This coil 46 may be wound with preferablyglass or polytetrafluoroethylene-insulated resistance wire, directly onto the cooling coil tubes 33. During the de-icing operation, the cooling fluid 41 may be drawn oif through the tube 47 to the collecting tank 45 (although this is not always necessary) by opening valve 44. Current may then be applied to the heating element 61 by means of the plug 48 connected to a suitable 110-volt, A.C. supply, for example. Valve 32 should be closed since the pressure will rise to 5 or p.s.i.g. in condensing chamber 2.

Valves

49 and 50 should now be opened to transfer all of the condensed liquid SP collected in condensing chamber 2 into storage chamber or tank 51. As soon as the pressure within condensing chamber 2 has risen to about 10 p.s.i.g. on gauge 52, indicating all ice has melted, condensation may proceed again, heater current through heater coil 46 can be stopped, cooling liquid 41 may again be recirculated,

valves

49, 50 closed and inlet valve 32 opened.

To remove the last 0.4 atmosphere of SF gas, a small quantity of liquid nitrogen is used in container cup 39, replacing the carbon dioxide, Dry Ice solution. The remaining gas will then condense on the cooling coils 33 in the form of ice or snow, which may be melted off at intervals, as previously described by the de-icer coil 46,

6 the liquid then being transferred to storage bottle or tank 51.

In the process of evacuating the gas in this manner, it is also possible to clean it of any are products. Most of these can be removed by means of an activated alumina filter 53 in the inlet line 29. CR, gas, however, may pass through the filter 53 into the condensing chamber 2. However, this CF gas may be drawn off by closing

valves

25, 49 and 50, cooling the condensing chamber 2 to the lowest possible value, and applying a vacuum for a few moments to branch outlet 30 opening valve 31. The GE; gas will come off from the condensing chamber 2 since it has a much higher vapor pressure than SF gas.

It will be observed that the casing 54 has an upper open end, and contains a heat insulation material 55, such as glass wool. The casing 54 is preferably portable as indicated by the wheels 56 and trailer hitch 57. Thus, the reclamation device may be easily transported to different circuit interrupters, and following the exhausting of the arc-extinguishing gas from one circuit interrupter 5, the

couplings

26, 28 may be removed, and the reclamation device 1 may be wheeled to another circuit interrupter 5 during the latters maintenance period. Thus, the reclamation device 1 may be employed to service a number of isolated circuit interrupters 5.

From the foregoing description, it will be apparent that there is provided an improved reclamation device associated with one or more circuit interrupters adaptable for freezing out or liquefying condensable arc-extinguishing gas employed in such circuit interrupters. By such reclaiming operations, the expense involved in supplying fresh gas is avoided, and the expense entailed in supplying carbon dioxide Dry Ice or liquid nitrogen is insignificant compared to the saving in expense resulting from reclaiming the arc-extinguishing gas.

Although the invention has been specifically described, and is particularly advantageous in conection with sulfur hexafluoride gas (SP it is to be clearly understood that such gas was used only for purposes of illustration and that, in fact, the reclamation device lot the present invention may be used with circuit interrupters employing other gases, such as enumerated above with advantage. As mentioned, the portability of the reclamation device 1 renders it suitable for servicing a large number of circuit interrupters 5 of the gas-type during periodic inspection periods.

The following are possible gases that may be used with their boiling points and possible coolants for their condensation:

Arc-Extinguish- Liqiligd air or liquid N2 or solid 00:.

D0. D0. Liquid air, or liquid N and solid 00;. Llq%d air or liquid N; or solid 00;.

Do. Liquid air or liquid nitrogen. Liquid air or liquid N or solid CO2. Liquid air, or solid CO2 and liquid N2- Liquid air, nitrogen or solid 002.

Although there has been shown and described only a single reclamation device, it is to be clearly understood that the same was merely for the purpose of illustration, and that changes and modifications may readily be made therein by those skilled in the art without departing from the spirit and scope of the invention.

I claim as my invention:

1. A portable liquefaction-type of reclamation device for detachable connection with gas-type circuit interrupters for reclaiming the arc-extinguishing gas therein during servicing operations including a portable truck carrying a casing having heat insulating material disposed therewithin, a condensing chamber disposed adjacent the upper end of the casing at least partially embedded within said heat insulating material and having a condensing coil extending therein, a heating element associated with said condenser coil, means for connecting the heating element to a source of electrical power for periodically heating said coil for de-icing purposes, a container cup for containing a coolant fluid, conduit means for interconnecting said container cup with the condensing coil, a storage tank for collecting liquefied arc-extinguishing gas disposed adjacent the lower end of said truck embedded within said heat insulating material, and additional conduit means interconnecting said storage tank with said condensing chamber, whereby the arc-extinguishing gas from the circuit interrupter may be liquefied and collected within said storage tank.

2. A portable liquefaction-type of reclamation device for detachable connection with gas-type circuit interrupters for reclaiming the arc-extinguishing gas therein during servicing operations including a portable truck carrying a casing having heat insulating material disposed therewithin, a condensing chamber disposed adjacent the upper end of the casing at least partially embedded within said heat insulating material and having a condensing coil extending therein, a heating element associated with said condenser coil, said heating element comprising a. heating coil encircling the condenser coil for an appreciable length, means for connecting the heating element to a source of electrical power for periodically heating said coil for deicing purposes, a container cup for containing a coolant fluid, conduit means for interconnecting said container cup with the condensing coil, a storage tank for collecting liquefied arc-extinguishing gas disposed adjacent the lower end of said truck embedded Within said heat insulating material, and additional conduit means interconnecting said storage tank with said condensing chamber, whereby the arc-extinguishing gas from the circuit interrupter may be liquefied and collected within said storage tank.

3. A portable liquefaction-type of reclamation device for detachable connection with gas-type circuit interrupters for reclaiming the arc-extinguishing gas therein during servicing operations including a portable truck carrying a casing having heat insulating material disposed therewithin, a condensing chamber disposed adjacent the upper end of the casing at least partially embedded within said heat insulating material and having a condensing coil extending therein, a heating element associated with said condenser coil, means for connecting the heating element to a source of electrical power for periodically heating said coil for de-icing purposes, a container cup for containing a coolant fluid, conduit means for interconnecting said container cup with the condensing coil, pump means for forcing coolant fluid through said conduit means and through the condensing coil, a storage tank for collecting liquefied arc-extinguishing gas disposed adjacent the lower end of said truck embedded within said heat insulating material, and additional conduit means interconnecting said storage tank with said condensing chamber, whereby the arc-extinguishing gas from the circuit interrupter may be liquefied and collected within said storage tank.

4. A portable liquefaction-type of reclamation device for detachable connection with gas-type circuit interrupters for reclaiming the arc-extinguishing gas therein during servicing operations including a portable truck carrying a casing having heat insulating material disposed therewithin, a condensing chamber disposed adjacent the upper end of the casing at least partially embedded within said heat insulating material and having a condensing coil extending therein, inlet pipe means associated with the upper end of the condensing chamber, valve-controlled vacuum-pipe means connected with the inlet pipe means for the extraction of relatively high-vapor-pressure contaminating gases, a coolant-liquid container cup, conduit means interconnecting the container cup with the condensing coil, pump means for forcing coolant-liquid through said conduit means and through the condensing coil, a storage tank for collecting liquefied arc-extinguishing gas disposed adjacent the lower end of said truck embedded within said heat insulating material, and additional conduit means interconnecting said storage tank with said condensing chamber, whereby the arc-extinguishing gas from the circuit interrupter may be liquefied and collected within said storage tank.

5. A portable liquefaction-type of reclamation device for detachable connection with. gals-type circuit interrupters for reclaiming the arc-extinguishing gas therein during servicing operations including a portable truck carrying a casing open at the upper end thereof and having heat insulating material disposed therewithin, a condensing chamber disposed adjacent the upper end of the casing at least partially embedded within said heat insulating material and having a condensing coil extending therein, said condensing chamber being removable from the truck through the upper open end of said casing, a heating element associated with said condenser coil, means for connecting the heating element to a source of electrical power for periodically heating said coil for de-icing purposes, a container cup for containing a coolant fluid, conduit means for interconnecting said container cup with the condensing coil, a storage tank for collecting liquefied arc-extinguishing gas disposed adjacent the lower end of said truck embedded within said heat insulating material, and additional conduit means interconnecting said storage tank with said condensing chamber, whereby the arcextinguishing gas from the circuit interrupter may be liquefied and collected within said storage tank.

References Cited by the Examiner UNITED STATES PATENTS 2,328,647 9/43 Jackson 629 2,511,419 6/50 Smith 62-275 2,571,014 10/51 Colburn et a1 62-12 2,738,658 3/56 Bronson 6210 2,895,303 7/59 Streeter.

2,955,182 10/60 Caswell et a1 ZOO-448.2 2,955,807 10/60 Riley et al. 62275 FOREIGN PATENTS 287,486 6/29 Great Britain.

NORMAN YUDKOFF, Primary Examiner.

ROBERT A. OLEARY, Examiner.

Claims

1. A PORTABLE LIQUEFACTION-TYPE OF RECLAMATION DEVICE FOR DETACHABLE CONNECTION WITH GAS-TYPE CIRCUIT INTERRUPTERS FOR RECLAMING THE ARC-EXTINGUISHING GAS THEREIN DURING SERVICING OPERATIONS INCLUDING A PORTABLE TRUCK CARRYING A CASING HAVING HEAT INSULATING MATERIAL DISPOSED THEREWITHIN, A CONDENSING CHAMBER DISPOSED ADJACENT THE UPPER END OF THE CASING AT LEAST PARTIALLY EMBEDDED WITHIN SAID HEAT INSULATING MATERIAL AND HAVING A CONDENSING OIL EXTENDING THEREIN, A HEATING ELEMENT ASSOCIATED WITH SAID CONDENSER COIL, MEANS FOR CONNECTING THE HEATING ELEMENT TO A SOURCE OF ELECTRICAL POWER FOR PERIODICALLY HEATING SAID COIL FOR DE-ICING PURPOSES, A CONTAINER CUP FOR CONTAINING A COOLANT FLUID, CONDUIT MEANS FOR INTERCONNECTING SAID CONTAINER CUP WITH THE CONDENSING COIL, A STORAGE TANK FOR COLLECTING LIQUEFIED ARC-EXTINGUISHING GAS DISPOSED ADJACENT THE LOWER END OF SAID TRUCK EMBEDDED WITHIN SAID HEAT INSULATING MATERIAL, AND ADDITIONAL CONDUIT MEANS INTERCONNECTING SAID STORAE TANK WITH SAID CONDENSING CHAMBER, WHEREBY THE ARC-EXTINGUISHING GAS FROM THE CIRCUIT INTERRUPTER MAY BE LIQUEFIED AND COLLECTED WITHIN SAID STORAGE TANK.