COOLING DEVICE FOR COOLING MEDIUM-VOLTAGE APPARATUS USING INSULATED HEAT PIPES
The cooling device is suitable for fitting to existing installations, without redesigning them. It consists in using heat pipes (12) that are partly embedded in the casing (10) of the apparatus. This embedded portion (12A) of the heat pipe (12) penetrating into the casing (10) has a sleeve (14) that is both electrically insulating and a good conductor of heat. The device is for application to circuit breakers in a medium-voltage, high-amperage electrical installation.
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The invention relates in particular to the field of circuit breakers or disconnectors for medium-voltage generators, placed in a protective sheath, and using cooling devices called “heat pipes” that operate with a phase-change heat-transfer fluid.
It should be recalled that a heat pipe is presented in the form of a long hermetically-sealed enclosure containing a fluid with its gaseous phase and its liquid phase in equilibrium, in the absence of any other gas, ignoring traces.
DEFINITIONHeat pipe: Thermal apparatus in the form of a long hermetically-sealed enclosure containing a fluid with its gaseous phase and its liquid phase in equilibrium. Heat is transferred from the hot portion to the cold portion of the tube by vaporizing the liquid phase and condensing the vapor in the cold portion.
PRIOR ART AND PROBLEM POSEDThe constant concern of makers of that type of equipment is to increase the ability of such apparatuses to conduct higher and higher currents, in particular for circuit breakers and disconnectors placed inside busbars at the outlets of power stations for producing or distributing electricity. That applies particularly for alternator circuit breakers.
A method that is generally used consists in making more uniform the temperature of the air that is in contact with the various heating and heated parts of the circuit breaker concerned. The cooling inside such a protective sheath may take place by natural or forced convection of the air enclosed therein and in which the circuit breaker is to be found, the prevailing temperature inside the protective sheath being considerably higher than the prevailing temperature outside, by 30° C. to at least 40° C.
Another solution consists in providing an increase in the current flow section in the various transmission elements, and thus increasing the size of circuit breaker parts.
Patent document EP 1 657 731 describes a known cooling device and method for cooling a high-voltage disconnector or a circuit breaker.
The object of the invention is to propose a different solution for this type of device.
SUMMARY OF THE INVENTIONTo this end, the invention mainly provides a cooling device using phase-change heat-transfer fluids for medium-voltage apparatus and comprising at least one heat pipe.
According to the invention the heat pipe(s) is/are placed in such a manner as to penetrate in part into the apparatus and is/are electrically insulated, in this embedded portion, by means of a sleeve that is both electrically insulating and a good conductor of heat.
In a first possible embodiment of the invention, the sleeve is made of sintered aluminium nitride.
In a second embodiment, the sleeve is made of sintered boron nitride.
Preferably, the outside portion of the heat pipe(s) riot penetrating into the apparatus terminating at a condenser is provided with an electrically insulating sleeve.
Each heat pipe may possess an electrically insulating ring on an outside portion of the electrically insulating sleeve.
In addition, each heat pipe may possess an electrically insulating sleeve on its outside portion.
The invention and its various technical characteristics can be better understood on reading the following description of three embodiments of the invention. The description is accompanied by six figures in which, respectively:
In
In
As shown by the heat pipe 12 on the left, the assembly may be completed by a ring made of electrically insulating material that surrounds the outside portion 14A of the electrically insulating sleeve in order to increase the creepage distance.
As shown by the heat pipe 12 on the left, the outside portion 12B may also possess a second electrically insulating sleeve 18 in order to increase the creepage distance.
With reference to
Generally the liquid returns by gravity, thereby leading the condenser 24 to be placed high up. If the inside of the heat pipe 12 is provided with channels, liquid return is accelerated by capillary force, and this also enables the condenser 24 to be placed lower down, while accepting a loss of efficiency.
In
Both heat pipes 12, shown in
In the embodiment of
The addition of suitable materials on the inside walls of the heat pipes 12, 42A and 42B also makes it possible for the heat pipes to be implanted upside down, and this increases cooling potential.
The main advantage of such a device is that it adapts to various heat pipe and cooling element technologies that have already been tested, without needing to develop insulation methods that need to contain the cooling liquid.
Claims
1. A cooling device using a phase-change heat-transfer fluid for medium-voltage apparatus, comprising:
- at least one heat pipe (12, 42A, 42B);
- the device being characterized in that the at least one heat pipe (12, 42A, 42B) penetrates in part into the apparatus and is electrically insulated in this embedded portion (12A) by means of a sleeve (14) that is both electrically insulating and a good conductor of heat.
2. A device according to claim 1, characterized in that the electrically insulating sleeve (14) is made of sintered aluminum nitride.
3. A device according to claim 1, characterized in that the electrically insulating sleeve (12, 42A, 42B) is made of sintered boron nitride.
4. A device according to claim 1, the assembly being placed inside a sheath (22), the device being characterized in that the outside portion (12B) of the heat pipes (12, 42A, 42B) not penetrating into the apparatus terminating at the condensers (24) possesses an electrically insulating sleeve (18).
5. A device according to claim 1, characterized in that each heat pipe (12) possesses an electrically insulating ring (16) placed on an outside portion (14A) of the electrically insulating sleeve (14).
6. A device according to claim 1, characterized in that each heat pipe (12, 42A, 42B) possesses an electrically insulating sleeve (18) on its outside portion.
Type: Application
Filed: Oct 25, 2010
Publication Date: Aug 16, 2012
Applicant: ALSTOM TECHNOLOGY LTD (Baden)
Inventors: Denis Frigiere (Decines), Didier Rodrigues (Serpaize), Jean-Marc Willieme (La Mulatiere)
Application Number: 13/502,421
International Classification: F28D 15/04 (20060101);