TRANSFORMER POWER ENHANCEMENT

Abstract

The present invention relates to the use, for increasing the power of a transformer, of at least one dielectric fluid of general formula (1):

(A-X).sub.n-B  (1)

in which A and B, which are identical or different, represent, independently of each other, an optionally substituted aromatic ring, X represents a spacer group and n represents 0, 1, 2 or 3.
The invention also relates to a transformer containing at least one dielectric fluid of general formula (1).

Claims

1-10. (canceled)

11. A method of increasing the power of a transformer comprising using at least one dielectric fluid having a general formula (1):
(A-X).sub.n-B  (1) wherein: A and B, which are identical or different, represent, independently of each other, an aromatic ring optionally substituted by one or more saturated or partially or completely unsaturated hydrocarbon radicals comprising from 1 to 20 carbon atoms, X represents a spacer group selected from the group consisting of a single bond, —O—, —S—, —(CRR′).sub.m—, >C═CRR′ and —NR″—, R and R′, which are identical or different, are chosen, independently of each other, from hydrogen and a saturated or partially or completely unsaturated hydrocarbon radical comprising from 1 to 6 carbon atoms, R″ represents a saturated or partially or completely unsaturated hydrocarbon radical comprising from 1 to 6 carbon atoms, m represents an integer of between 1 and 4, limits included, and n can be equal to 0 or represents an integer equal to 1, 2 or 3, with the restriction that, when n is equal to 0, B is substituted by one or more hydrocarbon radicals, as defined above.

12. The method of claim 11, wherein, in the dielectric fluid of general formula (1), n is different from 0 and B is an aromatic ring substituted by a hydrocarbon radical.

13. The method of claim 11, wherein, in the dielectric fluid of general formula (1), n is different from 0 and B is an aromatic ring substituted by an alkyl radical comprising from 1 to 6 carbon atoms.

14. The method of claim 11, wherein the at least one dielectric fluid of formula (1) is used in a mixture with one or more other dielectric fluids chosen from mineral oils, vegetable oils and natural or synthetic esters.

15. The method of claim 11, wherein the at least one dielectric fluid is chosen from benzyltoluene, dibenzyltoluene and their mixtures in all proportions.

16. The method of claim 11, wherein the at least one dielectric fluid is a benzyltoluene/dibenzyltoluene mixture comprising between 1% and 50%, limits included, with respect to the total amount of benzyltoluene/dibenzyltoluene.

17. The method of claim 11, wherein the at least one dielectric fluid further comprises one or more additives chosen from antioxidants, passivators, pour point depressants, decomposition inhibitors and their mixtures.

18. The method of claim 11, wherein the dielectric fluid comprises at least one decomposition inhibitor selected from the group consisting of carbodiimide derivatives, phenyl glycidyl ethers, or esters, alkyl glycidyl ethers, or esters, 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate, compounds of the anthraquinone family, epoxy derivatives, 3,4-epoxy-6-methylcyclohexylmethyl 3,4-epoxy-6-methylhexanecarboxylate, and epoxy resins of phenol novolak type or bisphenol A diglycidyl ether epoxys.

19. A transformer containing at least one dielectric fluid of formula (1) as defined in claim 11.

20. The transformer as claimed in claim 19, which is a distribution transformer or a power transformer.

Description

EXAMPLE

Comparison of Available Power Between a Mineral Oil and a Dielectric Fluid of Formula (1)

[0058] For the requirements of the example, use is made of two identical three-phase 160 kVA transformers, with a transformation factor of 15 kV to 0.4 kV. The comparative study is carried out with a transformer containing the mineral oil NYTRO Libra sold by Nynas, on the one hand, and with a transformer containing a Jarylec® sold by Arkema, on the other hand. The Jarylec® is a BT/DBT mixture.

[0059] A measurement of the temperature of the dielectric fluid contained in the transformer is carried out at the top of the phases, with respect to the charge of the transformer. The charging time to reach the temperature is 5 hours. All the conditions are the same over the 2 tests with the mineral oil and the Jarylec® sold by Arkema and in particular the condition with regard to the outside temperature, which is ambient temperature.

[0060] The voltage applied corresponds to the percentage of the nominal impedance of the short-circuit given by the manufacturer of the transformer. This impedance corresponds to 3.63% of the nominal voltage of 15 kV. Thus, at 100% charge, the voltage applied is approximately (15 000×0.0363) V.

[0061] The results of the tests are presented in tables 1 and 1a below:

TABLE-US-00001 TABLE 1 Charge Ambient Temperature Temper- Applied of the temperature (° C.) ature voltage transformer (° C.) NYTRO Libra difference (V)  70% 28.5 55.2 26.7 389 100% 28.8 76.3 47.5 557 115% — — — 640

TABLE-US-00002 TABLE 1a Charge Ambient Temperature Temper- Applied of the temperature (° C.) ature voltage transformer (° C.) Jarylec ® difference (V)  70% 28.4 52.3 23.9 389 100% 28.7 72.1 43.4 557 115% 28.7 76.5 47.8 640

[0062] A temperature difference of the same order of magnitude is obtained for a charge of 100% with the mineral oil and for a charge greater by 15% (i.e. 115%) with the Jarylec®. This shows that it is possible, with a dielectric fluid of general formula (1), to increase the power of a transformer, without causing overheating, in comparison with one and the same transformer not comprising dielectric fluid according to the general formula (1).