The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 28, 2002
Filed:
Dec. 10, 1998
Joachim Glatz-Reichenbach, Baden-Dättwil, CH;
Felix Greuter, Baden-Rütihof, CH;
Ruzica Loitzl-Jelenic, Kirchdorf, CH;
Jörgen Skindhoj, Frederiksberg, DK;
Ralf Strümpler, Gebenstorf, CH;
ABB Research Ltd., Zurich, CH;
Abstract
A protective element for protecting in particular an electric motor against overload currents includes in a polymer matrix, preferably ETFE, for example 40% (by volume) of a first powdered filler of a conductive material, preferably TiB , so that, as in the case of a PTC element, the resistance increases abruptly at a switching temperature corresponding to the melting temperature of the polymer. Also added are 20% (by volume) of a second powdered filler, a phase transition material which, at a critical temperature below the switching temperature, undergoes a phase transition in which it absorbs heat of transformation. As a result, the response time (T) of the protective element is notably extended in a range of the overload current factor (F) corresponding to higher permissible motor starting currents. Examples of materials which come into consideration for the second filler are those with a solid-solid phase transition such as pentaerythritol, NaNO , NaNO or else with a solid-liquid phase transition such as UHMWPE, quinol or, in particular, microencapsulated metals, alloys and salts.