US 12,467,009 B2
Synthetic ester and mineral oil dielectric fluids with increased stability
Todd L. Kurth, Maple Grove, MN (US); and Kevin R. Wirtz, Eden Prairie, MN (US)
Assigned to CARGILL, INCORPORATED, Wayzata, MN (US)
Filed by CARGILL, INCORPORATED, Wayzata, MN (US)
Filed on Oct. 18, 2023, as Appl. No. 18/489,444.
Application 18/489,444 is a continuation of application No. 16/982,203, granted, now 11,814,598, previously published as PCT/US2019/023152, filed on Mar. 20, 2019.
Claims priority of provisional application 62/646,121, filed on Mar. 21, 2018.
Prior Publication US 2024/0043766 A1, Feb. 8, 2024
This patent is subject to a terminal disclaimer.
Int. Cl. C10M 137/02 (2006.01); C10M 101/00 (2006.01); C10M 105/00 (2006.01); C10M 105/74 (2006.01); C10M 111/02 (2006.01); C10M 169/04 (2006.01); C10N 30/10 (2006.01); C10N 40/16 (2006.01); H01B 3/20 (2006.01); H01B 3/22 (2006.01); H01F 27/00 (2006.01); H01F 27/12 (2006.01); H01G 4/018 (2006.01); H01G 4/04 (2006.01); H01G 9/07 (2006.01)
CPC C10M 137/02 (2013.01) [C10M 101/00 (2013.01); C10M 105/00 (2013.01); C10M 105/74 (2013.01); C10M 111/02 (2013.01); C10M 169/04 (2013.01); H01B 3/20 (2013.01); H01B 3/22 (2013.01); H01G 4/018 (2013.01); H01G 4/04 (2013.01); H01G 9/07 (2013.01); C10M 2223/049 (2013.01); C10N 2030/10 (2013.01); C10N 2040/16 (2013.01); H01F 27/00 (2013.01); H01F 27/125 (2013.01)] 8 Claims
 
1. A dielectric fluid comprising:
a synthetic ester oil comprising a reaction product of a pentaerythritol and a C5-C12 linear or branched carboxylic acid;
a phosphite component having one to three aryloxy groups and comprising from 0.1 to 0.5 wt % of the dielectric fluid; and
a phenolic antioxidant component,
wherein, the amount of the phosphite component is sufficient to reduce the stray gassing of the dielectric fluid as determined by dissolved gas analysis (ASTM D3612-02, Method C) by at least 60% as compared to a like dielectric fluid composition that does not contain a phosphite component, wherein the stray gas is hydrogen, and wherein the dielectric fluid has a fire point greater than 300° C. as determined by ISO 2592 and has a breakdown voltage of at least 45 kV as determined by IEC 60156.