US 7,468,091 B2
Method for dehumidifying air and air dehumidifier for oil-insulated transformers, reactance coils and step switches
Karsten Viereck, Regenstauf (Germany); Dieter Dohnal, Lappersdorf (Germany); Ansgar Hinz, Leverkusen (Germany); and Reiner Brill, Nidda (Germany)
Assigned to Maschinefabrik Reinhausen GmbH, Regensburg (Germany)
Appl. No. 10/576,157
PCT Filed Dec. 03, 2004, PCT No. PCT/EP2004/013774
§ 371(c)(1), (2), (4) Date Apr. 17, 2006,
PCT Pub. No. WO2005/055255, PCT Pub. Date Jun. 16, 2005.
Claims priority of application No. 103 57 085 (DE), filed on Dec. 06, 2003.
Prior Publication US 2007/0199443 A1, Aug. 30, 2007
Int. Cl. H01F 27/14 (2006.01); B01D 53/26 (2006.01)
U.S. Cl. 95—10  [95/11; 95/21; 95/126; 96/111; 96/113; 336/58; 174/14 R] 4 Claims
OG exemplary drawing
 
1. Method of air dehumidification for oil-filled transformers, reactance coils and step switches for dehumidification of the air inducted into an oil expansion vessel, wherein the air humidity Fr is measured in the area between a granulate-filled housing of an air dehumidifier and the oil expansion vessel connected therewith, and wherein subsequently a comparison of the measured air humidity Fr with a predetermined limit value Fmax is undertaken and if the limit value is exceeded an electric heating device for baking the moisture-absorbing granulate in the interior of the housing is activated, characterised in that it is additionally detected whether an air flow is present between the housing (5) and the oil expansion vessel and if so which flow direction this air flow has and that the electric heating device is switched on only if either no air flow is present or this is directed outwardly from the oil expansion vessel.