Electrode water circulation and processing system for water rheostat

Abstract: The water rheostat A has a main electrode unit 61 including the main electrode 62 shaped as a hollow cylinder and provided with an electrode water inlet port 63 in the top of the hemispheri­ cal upper end portion 62a of the electrode 62, electrode water outlet ports 64 at equal intervals at the bottom 62c of the electrode 62 along the total circumference of the electrode 62. A sleeve 67 resistant to arc discharge is fitted in the circular recess 66a of the top portion of the sup­ port 66 the main electrode unit 61 so that the sleeve 67 is in contact with the inside circum­ ferential surface 66b of the top portion and a cir cumferential gap is defined between the bottom 62c of the main electrode 62 and the inside circum ferential surface 66b of the top portion of the su pport 66. An electrode water circulation pump 21 and a plurality of air and water cooling radiators 51 are provided in an electrode water cooling and circulation passage line 22 which is for feeding and draining a prescribed quantity of electrode water so that the temperature and amount of the electrode water in the water rheostat A are kept constant. A safety circuit breaker 50 is provided in the halfway portion of a power cable 4 for con­ necting the main electrode unit 5 to a power sup­ ply 48, so that the breaker 50 is turned off when the flow rate of the electrode water through the electrode water cooling and circulation passage line 22 is less than a prescribed value. A spray nozzle unit 10 and a motor 31 coupled with a fan 11 are provided in the face of the rear of the body of each of the radiators 51 so that the moter 31 is located behind the spray nozzle unit 10. The front of the body 54 of each of the radiators 51 is covered with a hood having a steam re­ lease port 57a in the top 54 of the hood 55.

Description: The present invention relates to an electrode water circulation and processing system for a water rheostat, for example for measuring or testing the output characteristics of a power supply such as an electricity generator and an inverter. As shown in Figure 1, a conventional water rheostat A designed by the present inventor comprises a base electrode 1 in the shape of a cylinder containing a prescribed amount of electrode water W which is circulated through the electrode, a main electrode 5 in the shape of a cylinder and extending vertically through an electrically insulating support 3 passing through the centre of the bottom la of the base electrode 1, and an electrically insulating cylinder 7 surrounding the main electrode 5 and vertically slidable to adjust the length of the uncovered portion of the main electrode 5. A water drain hole 2 is provided in an appropriate portion of the bottom la of the base electrode 1. A power cable 4 for a power supply (not shown in Figure 1) is connected to the lower end of the main electrode 5, which extends outside the electrically insulating support 3. A water feed port 6 is provided in the upper portion of the electrically insulating cylinder 7 so that the cooled water W is fed through the port 6. A plurality of such water rheostats A are provided (though not all of them are shown in Figure 1), and the main electrodes 5 of the rheostats A are connected to a single phase or three phase power supply, and the base electrodes 1 of the rheostats A are connected to each other by way of an earth cable 8 and grounded. If the number of phases of the power supply is three, the water rheostats A are Y-connected to each other. The water feed port 6 and the water drain hole 2 in each of the rheostats A communicate with an electrode water cooling and processing unit B shown in Figure 1 and disclosed in the Japanese Patent Specifications Nos. 123287/1987 and 124474/1987. The electrode water cooling and processing unit B functions so that the warmed water W drained from the water rheostat A is cooled and sent back to the rheostat A. The unit B comprises a radiator 9, a spray pipe 10 for spraying water onto the rear of the radiator 9, a fan 11 for blowing air from behind the spray pipe 10, a duct 12 by which the air blown on to the radiator 9 by the fan 11 and flowing to the front of the radiator 9 is guided so that the air is dispersed upward, a recovered water tank 13 provided under the radiator 9 to recover the water sprayed from the spray pipe 10 onto the radiator 9, and a storage tank 14 for storing the electrode water W which is circulated through the water rheostat A and the radiator 9. The cooling and processing unit B has a pure water filling passage line 20, an electrode water cooling and circulation passage line 22, a flushing return passage line 24, and a spray water feed passage line 27 linking the radiator 9, the spray pipe 10, the recovered water tank 13 and the storage tank 14. The pure water filling passage line 20 serves for the supply of electrode water W from the storage tank 14 pumped by a pure water pump 16 through a water feed pipe 15 extending into the storage tank 14, the water being processed through filters 17 and 18 and a water purifier 19 which heightens the purity of the water. The electrode water cooling and circulation passage line 22 serves for the supply of electrode water W received from the pure water filling passage line 20 to the water rheostat A by way of the feed portion 22a, and for the supply of the warmed water drained from the rheostat A to the lower inlet port 9a of the radiator 9 by way of an electrode water circulation pump 21 provided in the electrode water cooling and circulation passage line 22. The flushing return passage line 24 serves for the return of electrode water W extracted from the drain portion 22b of the electrode water cooling and circulation passage line 22 upstream of the lower inlet port 9a of the radiator 9 to the pure water filling passage line 20 by way of a cooling coil 23 and the pure water pump 16. The spray water feed passage line 27 serves for the supply to the spray pipe 10 of water pumped by a spray pump 25 through one of the water feed pipe 15 and a suction pipe 26 extending into the recovered water tank 13. The cooling and processing unit B also includes changeover valves 28, 29 and 30 connected to the passage lines 20, 22, 24 and 27. A fan motor 31, speed controllers 32, 33 and 34 in the form of inverters serve to regulate the speeds of the fan motor 31, the pure water pump 16 and the spray pump 25, and a cooling coil 35 is also provided. Shown at C in Figure 1 is an automatic control unit for vertically moving the electrically insulating cylinder 7. The automatic control unit C comprises a measuring instrument 36 which measures at least one of the electrical power and current supplied through the power cable 4 and sends out a measured value signal S1 corresponding to the electrical power or current, a controller 37 which receives the signal S1 and sends out a control signal S2 resulting from comparison of the signal S1 with a preset value, and an operating unit 38 which receives the control signal S2 to move the electrically insulating cylinder 7. The water rheostats A, the electrode water cooling and processing unit B, the automatic control unit C and the associated components can be installed on the cargo bed of a truck or the like so as to be capable of being rapidly transported. The operation of the electrode water cooling and processing unit B is described in detail hereinafter. The purified water is supplied to the feed portion 22a of the electrode water cooling and circulation passage line 22 by way of the water feed pipe 15 of the pure water filling passage line 20 and passes into the water rheostat A through the water feed port 6, as shown by full-line arrows in figure 1. The water is pumped up from the storage tank 14 by the pure water pump 16 so that the water flows through the pump 16 and the cooling coil 35, and has sand and the like removed therefrom by the filter 17 and chlorine removed therefrom by the filter 18 before the water enters the water purifier 19. Although the electrical conductivity of the water entering the water purifier 19 is about 200 µs/cm, the conductivity is decreased to about 1 µs/cm by the purifier 19. If the electrical conductivity of the water rises due to the dissolution of an impurity in the water as a result of the initial rotation of the electrode water pump 21, the water is drained and then subjected to the above-described processing and filling again. Since the maximum operating temperature of the water purifier 19 is 40°C, the cooling coils 23 and 35 are used to keep the temperature of the water not higher than 40°C. After the pure water filling passage line 20 has been closed by the changeover valves 29 and 30, the electrode water circulation pump 21 is activated so that electrode water W is circulated through the electrode water cooling and circulation passage line 22, as shown by dotted-line arrows in Figure 1. At the same time, the spray pump 25 is activated so that the water in the storage tank 14 is pumped up through the water feed pipe 15 and fed to the spray pipe 10 by way of the spray water feed passage line 27, as shown by dotted-line arrows in Figure 1, and is then sprayed from the spray pipe 10 onto the radiator 9 as shown in Figure 1. The fan motor 31 is also activated to rotate the fan 11 to blow the air from behind the radiator 9. As the electrode water W flows through the water rheostat A, the water acts as an electrical resistance so that it consumes electrical power and is warmed thereby. The warmed water W is then supplied to the radiator 9 so that the water is cooled by the sprayed water while the warmed water flows through the radiator 9. The sprayed water is evaporated on the surface of the radiator 9 by the heat of the warmed water W flowing through the radiator, and is then conducted by the air blown from behind the radiator 9 by the fan 11 so that the evaporated water and air are diffused upwardly along the guide plates 12a of the duct 12 in front of the radiator 9, as shown by dotted lines in Figure 1. The electrode water W thus cooled by the radiator 9 flows out therefrom through the outlet port 9b and is then fed again to the water rheostat A through the feed portion 22a of the electrode water cooling and circulation passage line 22. Some sprayed water, which is sprayed onto the radiator 9 to cool the warmed water W therein but is not evaporated by the heat thereof, adheres to the duct 12 and falls therefrom under the action of gravity so as to be recovered by the recovered water tank 13. When the water in the tank 13 has risen to the vicinity of the maximum level, the changeover valve 28 is switched so that the water is pumped up by the spray pump 25 through the suction pipe 26 and supplied to the spray pipe 10. The recovered water tank 13 and the storage tank 14 may be connected to each other so as to dispense with the changeover valve 28 and the suction pipe 26. If the electrical conductivity of the electrode water W needs to be decreased during the operation of the water rheostat A at high voltage, the changeover valves 29 and 30 are switched so that the water shown by two-dot-chain line arrows in Figure 1 is circulated through the flushing return passage line 24, the pure water filling passage line 20 and the electrode water cooling and circulation passage line 22. The electrode water W is then drained from the water rheostat A by the electrode water circulation pump 21, passed to the cooling coil 35 through the other cooling coil 23 by the pure water pump 16 and returned to the water rheostat A through the filters 17 and 18 and the water purifier 19, so that the water is removed of extraneous substances, such as chlorine, etc., thus decreasing the electrical conductivity of the water. If the water rheostat A is to be operated with a high electrical current at a low voltage, an electrically conductive salt is dissolved in the electrode water W to render the electric conductivity thereof higher than that, e.g. 200 µs/cm, of ordinary tap water, and the electrode water W is then circulated through the rheostat A and the electrode water cooling and circulation passage line 22. An electrode water temperature control unit D comprises a temperature measuring instrument 39, a temperature comparator 40, the speed controllers 32 and 34, the operating unit 38, an alarm 41, and a safety circuit breaker 42. The temperature measuring instrument 39 is provided at the lower inlet port 9a of the radiator 9 connected to the end of the drain portion 22b of the electrode water cooling and circulation passage line 22, and measures the temperature of the electrode water W flowing through the lower inlet port 9a, so that the instrument 39 sends out a measured values signal S3. The temperature comparator 40 receives the measured value signal S3, and sends out a control signal S4 resulting from the comparison of the measured value signal S3 with a preset value. If the control signal S4 has exceeded a preset allowable maximum temperature value, the comparator 40 sends out an emergency signal S5. The speed controllers 32 and 34 are in the form of inverters which are adapted to receive the control signal S4 so as to regulate driving of the motor of the spray pump 25 and of the motor 31 of the fan 11. When the operating unit 38 receives an emergency signal S5, the unit 38 disengages a clutch (not shown in Figure 1). When the alarm 41 receives the emergency signal S5, it emits a warning sound. At the same time, the safety circuit breaker 42 disconnects the power supply and the water rheostat A from each other. The automatic control unit C and the electrode water temperature control unit D are included in a conventional electrode water circulation and processing system X for the water rheostat A so as to provide safety measures in the event of abnormal operation. If the electrode water circulation pump 21 has stopped or the driving capacity thereof has sharply fallen during the operation of the water rheostat A so that the flow rate of the electrode water W from the pump 21 has drastically decreased, the circulated quantity of water becomes zero or is reduced with the result that there is a sharp rise in the temperature of the water in the base electrode 1 which may cause the water to boil and to overflow. This phenomenon is very dangerous. Furthermore, since there is a time lag until the temperature measuring instrument 39 detects the sharp rise in the temperature of the electrode water W, arc discharge α may occur between the base electrode 1 and the main electrode 5 during the time lag, as a result of the main electrode no longer being covered by the water. Until a short-circuit overcurrent due to the arc discharge is detected by the measuring instrument 36, the electrically insulating cylinder 7 is now moved down to completely cover the main electrode 5 in order to insulate it. For these reasons, the moving down of the cylinder 7 to insulate the main electrode 5 is likely to occur too late to avoid a dangerous incident resulting from the occurrence of the arc α. Let us suppose now that vertical and parallel electrode plates P1 and P2 face each other in a fixed amount of water L in the water rheostat A′, as shown in Figure 2. When a voltage E applied to the electrode plates P1 and P2 is increased to a certain value, discharge takes place between the plates. If the electrode plates P1 and P2 were infinitely-extensive flat plates parallel with one another, the discharge would be most unlikely to take place between them. However, such infinitely-extensive flat plates do not exist in reality. The potential V on the surface of the electrode plate is expressed as follows: V = K Q r in the equation, K, Q and r denote a coefficient, the amount of electrical charge and the radius of curvature of the electrode plate, respectively. Since the electrode plate is flat, the radius r of curvature is infinitely large. However, the potential V on the corner Θ of the electrode plate is equal to that in the case of r 0. The potential V in the case of r 0 is infinitely high as understood from the above equation. Therefore, the discharge is most likely to take place on the corner of the electrode plate. The corner of each of the electrode plates can be eliminated by shaping the plate as a sphere or a cylinder. For such purpose, the main electrode 5 is composed of upper and lower hemispherical end portions 5a and 5b and an intermediate cylindrical portion 5c, as shown in Figure 3. Since the radius of curvature of the cylindrical base electrode 1 located outwardly of the main electrode 5 is larger than that of the main electrode 5, the potential on the base electrode 1 is lower than that on the main electrode 5. The discharge in the water W between the main electrode 5 and the base electrode 1 in the water rheostat A takes place due to a bubble generated by the local heating of the surface of the main electrode 5. When the bubble is generated between the electrodes 1 and 5, the area of substantial mutual facing of the electrodes fluctuates. Since the movement of the bubble is irregular, the electrical resistance between the electrodes 1 and 5 changes irregularly so that dielectric breakdown occurs. The only means for preventing and removing the bubble is cooling and cleaning of the surface of the main electrode 5 with a uniform rapid flow of water. A conventional water rheostat of such kind was invented by the present inventor and disclosed in Japanese Patent Application No. 251652/1987. In this, the form and constitution of the main electrode unit 43 of the water rheostat A was modified as shown in Figure 4. Figure 4 shows the electrically insulating support 3, the main electrode 5 on the support 3, an electrode connection rod 44, the bottom la of the base electrode 1, a fixed block 45 secured to the bottom la of the base electrode 1 by screws 46, and an annular seal 47 for preventing electrode water leakage. The bottom 5a of the main electrode 5 is made flat in order to stably support the electrode 5 on the support 3, although a curved chamfer 5b is provided at the periphery of the bottom 5a. The radius of curvature of the curved chamfer 5b is so small that, when the temperature of the electrode water has risen to 65°C, a bubble is generated on the curved chamfer 5b and arc discharge takes place at the bubble. For that reason, the maximum electrical power applicable to the electrodes 1 and 5 is 650 kw. Because of the arc discharge, the electrical power output across the electrodes 1 and 5 is likely to fluctuate so as to tend to hinder proper measurement in a load test, reduce mechanical capacity and cause a burnout accident. Since the conventional electrode water circulation and processing system X has only the radiator 9, the spray pipe 10, the fan 11 and the duct 2 for cooling the electrode water W, the cooling capacity of the system X is relatively low. However, if the radiator 9 is made larger in size to increase the cooling capacity of the system X, the radiator 9 occupies a larger space and the cost of the equipment and the cost of running the system X are increased. For that reason, the output characteristics of the power supply cannot be measured with a high current at a high voltage with the use of the system X. It is another object of the present invention to provide an electrode water circulation and processing system for a water rheostat having a main electrode whose form and constitution are such that arc discharge is less likely to occur on the main electrode. According to the present invention there is provided an electrode water circulation and processing system for a water rheostat, the system comprising a water rheostat having a main electrode unit, an electrode water circulation pump and a cooling radiator provided in an electrode water cooling and circulation line which is in fluid communication with said water rheostat for feeding to and draining from said water rheostat a prescribed quantity of electrode water so that the temperature and amount of electrode water in said water rheostat are kept constant, and a safety circuit breaker provided in a power cable for connecting said main electrode unit to a power supply, characterised in that a flow meter provided in said line at the outlet side of said pump is operatively associated with the circuit breaker so that, when said meter detects that the flow rate of electrode water through said pump is less than a prescribed value, the circuit breaker is operated to cut off supply of power to said main electrode unit, and in that said main electrode unit comprises a main electrode in the form of a hollow cylindrical body having a hemispherical upper end portion through which an electrode water inlet port extends, and a bottom end portion having electrode water outlet ports equiangularly distributed around the circumference thereof, an electrically insulating support having a circular recess in the top thereof, and an electrode connection rod extending through an axial bore in said support and having an upper end portion which projects from the upper end of said axial bore and is fixedly coupled to the bottom end portion of said main electrode which is inserted in said recess so that a circumferential gap is defined between the bottom end portion of said main electrode and an inner circumferential surface at the top of said support. In order that the invention may be more fully understood, reference will now be made, by way of example, to the accompanying drawings, in which: Figure 1 is a diagram of the piping and wiring of a conventional electrode water circulation and processing system for a water rheostat; Figure 2 is an explanatory diagram illustrating the relationship between discharge and electrode plates; Figure 3 is an explanatory diagram illustrating the ideal form of a main electrode; Figure 4 is a longitudinal section through a conventional main electrode; Figure 5 is a diagram of the piping and wiring of an electrode water circulation and processing system for a water rheostat according to the present invention; Figure 6 is a side view of an air and water cooling radiator which has a hood for use with the present invention; Figure 8 is a plan view of the air and water cooling radiator shown in Figure 7; and Figure 9 is a longitudinal section through a main electrode for a water rheostat according to the present invention. Embodiments of the present invention are hereafter described in detail with reference to the drawings attached hereto. Equivalent parts shown in the drawings are denoted by the same reference symbols. Figure 5 shows an electrode water circulation and processing system Y for a water rheostat A according to the present invention. A power supply 48 shown in Figure 5 is a three-phase power supply. In the system Y, a flow meter 49, which is of the flow switch type and is normally used at the pressure of 1 kg/cm², is provided in the drain portion 22b of an electrode water cooling and circulation passage line 22 near the outlet port 21a of an electrode water circulation pump 21. A safety circuit breaker 50 is provided in the three-phase power cables 4. When it is detected by the flow meter 49 that the quantity of electrode water W discharged from the outlet port 21a of the circulation pump 21 has become less than a preset value, an electrical current cutoff command signal S6 is generated to quickly turn off the circuit breaker 50 to stop supply of an electrical current from the power supply 48 to the water rheostat A. Three air and water cooling radiators 51 having hoods are provided in the electrode water cooling and circulation passage line 22 and are connected in series so that the cooling capacity of the system Y for the electrode water W is heightened. Shown at 52 and 53 in Figure 5 are a power switch and a processing section which includes pipes and appliances 13, 14, 15, 16, 17, 18, 19, 23, 25, 26, 27, 28, 29, 30, and 35 and is connected to the electrode water cooling and circulation passage line 22 through a flushing return passage line 24 and a pure water filling passage line 20. The safety circuit breaker 50 may include the function of the safety circuit breaker 42 shown in Figure 1. In each of the radiators 51, the hood 55, having a steam release port 55a in the top of the hood 55 and having a curved bottom 55b, and a cover 56, having an air suction port 56a in the rear of the cover 56, are integrally coupled to the front and rear of the body 54 of the radiator 51 so that the hood 55 and the cover 56 communicate with each other, as shown in Figure 6. A spray nozzle means 10 and a motor 31 coupled to a fan 11 are provided in the cover 56. Figures 7 and 8 show an alternative radiator 51′. In the radiator 51′, a hood 57, having a steam release port 57a in the top of the hood 57 and having sides each shaped as an inverted right-angled triangle, i pivotally coupled at the bottom to the body 54 of the radiator 51′ at the bottoms of the front portions of the right and left sides of the body 54 so that the hood 57 can be freely swing. When the radiator 51′ is not in use, the hood 57 is swung back so that it is folded as shown by chain lines in Figure 7. When the radiator 51′ is put in use, the hood 57 is swing forth so that the right and left side edges 57b thereof are engaged with edge stoppers 54a projecting from the right and left sides of the body 54 of the radiator 51′, as shown by full lines in Figures 7 and 8. A door plate 59 capable of closing the air suction port 56a of the cover 56 of the radiator 51′ is pivotally coupled by means of a pivot 60 at the upper edge of the door plate 59 to the edge of the cover 56, so that the door plate 59 extends downwardly and can be freely swung to open and close the port 56a. When the radiator 51′ is not in use, the door plate 59 closes the air suction port 56a. When the radiator 51′ is put in use, the door plate 59 opens the air suction port 56a as shown by full lines in Figures 7 and 8. When the radiator 51′ is not in use, it is folded as described above to occupy a smaller space and to be tightly closed to prevent rain water or dust from entering into the radiator 51′ when the electrode water circulation and processing system Y is installed outdoors or on a vehicle. As shown in Figure 9, the main electrode unit 61 of the water rheostat A comprises a main electrode 62 shaped as a hollow cylindrical body, an electrically insulating support 66 made of ceramic, polypropylene or the like and resistant to arc discharge, and an electrode connection rod 69. The main electrode 62 has an electrode water inlet port 63 in the top of the hemispherical upper end portion 62a of the electrode 62. The bottom 62c of the main electrode 62 is provided with a curved chamfer 62b at the periphery of the bottom 62c. A tapped hole 65 extends through the centre of the bottom 62c of the main electrode 62. Electrode water outlet ports 64 are provided at equal intervals in the main electrode 62 near the bottom 62c thereof along the total circumference of the electrode 62. A sleeve 67 made of ceramic or the like and resistant to arc discharge is fitted in a circular recess 66a in the top portion of the support 66 so that the sleeve is in contact with the inside circumferential surface 66b of the top portion of the support 66. The support 66 is fitted through the centre of the bottom la of the base electrode 1 of the water rheostat A. The electrode connection rod 69 extends through an axial hole 68 in the support 66. The threaded portion 69a of the rod 69, which extends through the upper end of the axial hole 68, is engaged in the tapped hole 65 of the bottom 62c of the main electrode 62 inserted in the circular recess 66a in the support 66 in such a manner that a prescribed circumferential gap ℓ is defined between the main electrode 62 and the inside circumferential surface of the sleeve 67. A fixed block 45 is secured to the bottom la of the base electrode 1 by screws 46. An annular seal 47 is fitted on the support 66 to prevent the electrode water W from leaking. When the sleeve 67 is fitted in the circular recess 66a in the top portion of the support 66, the top portion is heated to increase the diameter of the inside circumferential surface 66b thereof and press-fit the sleeve 67 into the recess 66a. After the press-fitting, the top portion of the support 66 is cooled to the room temperature to decrease the diameter of the inside circumferential surface 66b thereof. The sleeve 67 is thus firmly fitted in the recess 66a of the support 66. The sleeve 67 may otherwise be firmly fitted in the recess 66a. The depth of the recess 66a is such that the electrode water outlet ports 64 are located in the recess 66a. The bottom 62c of the main electrode 62 and the upper end of the electrode connection rod 69 may be coupled to each other by another means, such as by inserting the threaded portion 69a of the rod into the tapped hole 65 in the bottom 62c and tightening a nut on the threaded portion 69a, and welding the bottom 62c to the upper end of the rod 69. If the flow rate of the electrode water W in the electrode water cooling and circulation passage line 22 has become zero or less than a prescribed value due to the stoppage of the electrode water pump 21, or the fall in the capacity thereof or the like during the operation of the electrode water circulation and processing system Y, the flow meter 49 immediately detects such a change in the flow rate of the water W to turn off the safety circuit breaker 50 to quickly cut off the electrical power from the power supply 48 to stop the output characteristic measuring test thereof before the temperature of the electrode water W in the base electrode 1 of the water rheostat A rises to boil the water W and allow arc discharge to occur. Since the plural radiators 51 having hoods 55 are provided in the electrode water cooling circulation passage line 22, the electrode water cooling capacity of the system Y is high enough for the system Y to adequately work for the output characteristic measuring test of the power supply 48 at a heavy current at high voltage. If the consumption of electrical power by the water rheostat A increases by 14.8 kw/°C for every Celsius degree of the difference between the temperature of the electrode water W in the rheostat A and that of the outside air, the maximum allowable water temperature for a conventional electrode water circulation and processing system X and that for the system Y of this embodiment are 65°C and 75°C, respectively, and, if the temperature of the outside air is 25°C, for instance, the margin in the electrode water cooling capacity of each of the systems X, Y is calculated as follows: The conventional system: 65°C - 25°C = 40°C 40°C x 14.8 kw/°C = 592 kw The present system Y: 75°C - 25°C = 50°C 50°C x 14.8 kw/°C = 740 kw Comparison of the systems: 740 kw - 592 kw = 148 kw Therefore, the electrode water cooling capacity of the system Y is higher than that of the conventional system X by 148 kw. In other words, the allowable amount of heat generated by the water rheostat A connected to the power supply 48 is larger for the system Y than for the conventional system X. As described above, the flow meter 49 is provided immediately downstream of the electrode water circulation pump 21 to provide safety measures to prevent the electrode water W in the water rheostat A from boiling and overflowing due to an accident such as a fault in the pump 21, a fall in the capacity thereof and clogging of the electrode water cooling and circulation passage line 22 so as to let the arc discharge occur in the rheostat A. Besides, the plural radiators 51 having hoods 55 are provided in series with each other in the passage line 22 to make the electrode cooling capacity of the electrode water circulation and processing system Y high enough to enable the system Y to work for the output characteristic measuring test of the power supply 48 at a heavy current at high voltage. The electrode water W processed to a prescribed temperature and a prescribed electrical conductivity by the circulation and processing system Y during the circulation of the water W falls onto the top of the main electrode 62 of the main electrode unit 61 of the water rheostat A as shown by arrows in Figure 9, so that some of the water W enters into the main electrode 62 through the electrode water inlet port 63 at the centre of the top thereof, flows down on the inside surface of the electrode 62, and goes out of the electrode 62 into the circumferential gap ℓ through the electrode water outlet ports 64 near the bottom 62c of the electrode 62, as shown by arrows in Figure 9. The curved chamfer 62b of the bottom 62c of the main electrode 62 is located in the circular recess 66a in the electrically insulating support 66 so that the curved chamfer 62b, on which the arc discharge is most likely to occur, is not exposed to the base electrode 1, and the electrode water W flowing through the electrode water outlet ports 64 and the circumferential gap ℓ constantly cools the bottom 62c to prevent a bubble from being generated due to the local heating of the bottom 62c so as to cause dielectric breakdown resulting in the arc discharge. Even if the arc discharge should occur, the electrically insulating support 66 does not burn because it is protected by the sleeve 67 resistant to arc discharge. Thus, the inside and outside surfaces of the main electrode 62 are cooled by the flowing electrode water W constantly circulated and cooled by the electrode circulation and cooling system Y, so that the temperature of the electrode 62 is not locally increased. Besides, the bottom of the main electrode 62, on which the arc discharge is most likely to occur, is located deep in the circular recess 66a fitted with the sleeve 67 and is constantly cooled by the electrode water W, so that the arc discharge temperature for the system Y is 75°C which is higher by 10°C than that of 65°C for the conventional system X. As a result, the maximum applicable electrical power for the system Y is higher than that for the conventional system X. For that reason, the range of measurability for the output characteristics of the power supply with the use of the system Y is wider than that with the use of the conventional system X although the systems X, Y are the same in size. In other words, the capacity of the system Y is higher than that of the conventional system X.

Claims: An electrode water circulation and processing system for a water rheostat, the system comprising a water rheostat (A) having a main electrode unit (61), an electrode water circulation pump (21) and a cooling radiator (9) provided in an electrode water cooling and circulation line (22) which is in fluid communication with said water rheostat (A) for feeding to and draining from said water rheostat (A) a prescribed quantity of electrode water (w) so that the temperature and amount of electrode water (w) in said water rheostat (A) are kept constant, and a safety circuit breaker (42) provided in a power cable (4) for connecting said main electrode unit (61) to a power supply, characterised in that a flow meter (49) provided in said line (22) at the outlet side of said pump (21) is operatively associated with the circuit breaker (42) so that, when said meter (49) detects that the flow rate of electrode water (w) through said pump (21) is less than a prescribed value, the circuit breaker (42) is operated to cut off supply of power to said main electrode unit (61), and in that said main electrode unit (61) comprises a main electrode (62) in the form of a hollow cylindrical body having a hemispherical upper end portion (62a) through which an electrode water inlet port (63) extends, and a bottom end portion (62c) having electrode water outlet ports (64) equiangularly distributed around the circumference thereof, an electrically insulating support (66) having a circular recess (66a) in the top thereof, and an electrode connection rod (69) extending through an axial bore (68) in said support (66) and having an upper end portion (69a) which projects from the upper end of said axial bore (68) and is fixedly coupled to the bottom end portion (62c) of said main electrode (62) which is inserted in said recess (66a) so that a circumferential gap is defined between the bottom end portion (62c) of said main electrode (62) and an inner circumferential surface (66b) at the top of said support (66). An electrode water circulation and processing system according to the claim 1, wherein a plurality of air and water cooling radiators (9) are provided in the electrode water cooling and circulation line (22). An electrode water circulation and processing system according to the claim 1 or 2, wherein the electrode water outlet ports (64) of the main electrode (62) are located in the circular recess (66a) in the top of the electrically insulating support (66). An electrode water circulation and processing system according to the claim 1, 2 or 3, wherein a sleeve (67) resistant to arc discharge is fitted in the circular recess (66a) in the top of the electrically insulating support (66) so that said sleeve (67) is in contact with the inner circumferential wall of the recess (66a). An electrode water circulation and processing system according to any preceding claim, wherein the electrically insulating support (66) is made of ceramic. An electrode water circulation and processing system according to any preceding claim, wherein the main electrode (62) has a tapped through hole (65) in the centre of the bottom end portion (62c) of said electrode (62), and the upper end portion (69a) of the electrode connection rod (69) is threaded to engage in said hole (65). A water rheostat (A) having a main electrode unit (61) through which a prescribed quantity of electrode water is circulated by an electrode water cooling and circulation line (22) incorporating an electrode water circulation pump (21) and a cooling radiator (9) so that the temperature and amount of electrode water (w) in said water rheostat (A) are kept constant, and a power cable (4) for connecting said main electrode unit (61) to a power supply and incorporating a safety circuit breaker (42), characterised in that said main electrode unit (61) comprises a main electrode (62) in the form of a hollow cylindrical body having a hemispherical upper end portion (62a) through which an electrode water inlet port (63) extends, and a bottom end portion (62c) having electrode water outlet ports (64) equiangularly distributed around the circumference thereof, an electrically insulating support (66) having a circular recess (66a) in the top thereof, and an electrode connection rod (69) extending through an axial bore (68) in said support (66) and having an upper end portion (69a) which projects from the upper end of said axial bore (68) and is fixedly coupled to the bottom end portion (62c) of said main electrode (62) which is inserted in said recess (66a) so that a circumferential gap is defined between the bottom end portion (62c) of said main electrode (62) and an inner circumferential surface (66b) at the top of said support (66). A water rheostat according to claim 7, wherein the electrode water outlet ports (64) of the main electrode (62) are located in the circular recess (66a) in the top of the electrically insulating support (66). A water rheostat according to claim 7 or 8, wherein a sleeve (67) resistant to arc discharge is fitted in the circular recess (66a) in the top of the electrically insulating support (66) so that said sleeve (67) is in contact with the inner circumferential wall of the recess (66a). A water rheostat according to claim 7, 8 or 9, wherein the main electrode (62) has a tapped through hole (65) in the centre of the bottom end portion (62c) of said electrode (62), and the upper end portion (69a) of the electrode connection rod (69) is threaded to engage in said hole (65).

Inventors: MATSUMOTO KESAFUMI, MATSUMOTO, KESAFUMI
Applicants: KOKEN KK, KOUKEN CO. LTD.
Application year: 1989
Main classification: H01C10
IPC codes: H01C10