Abb Research Ltd.

Abb Ab

Joachim Glatz-Reichenbach

Ralf Str&uuml;mpler

Felix Greuter

Ralf Strumpler

Jorgen Skindhoj

Erkki Rajala

Ruzica Loitzl-Jelenic

Lars X Eriksson

Uwe Kaltenborn

Timo Jokiniemi

Peter Isberg

Claus Schuler

Henning Fuhrmann

Krister Linnarud

Ralf Strümpler

Zdenek Pelanek

Gerhard Mauthe

Martin Thiele

J&ouml;rgen Skindhoj

Mats M Johansson

A contactor has two contact elements () each having a contact member () adapted to bear with the contact side () thereof against a said contact side of the other contact member for enabling an electric current to flow between said to contact elements. The contact sides of both contact members are provided with serration's () extending so that elongated ridge-like peaks () of serration's of one said contact side intersect such peaks of the other said contact side while forming a plurality of spots of mutual contact of these contact sides distributed over the area of said contact sides.

Serrated contact members

A compressor includes a compressor wheel, a diffuser and a device for the wet cleaning of the diffuser of a compressor, the diffuser being arranged downstream of the compressor wheel in the flow direction of the medium to be compressed. The device includes an arrangement for injecting a liquid, which is arranged in such a way that the liquid can be introduced, downstream of the compressor wheel, to the diffuser. The diffuser has at least partially a non-stick coating. A device of this type is suitable for removing deep-seated deposits from the surface of the diffuser.

Compressor cleaning system

The invention relates to a novel method of producing a resistor device comprising a PTC-polymer elementand a varistor element. Both elements are molded in a common molding process using one common mold. Preferred is co-injection molding. The invention further relates to the resistor device thus produced and a current limit means including the resistor device and a switch (FIG.).

Method of producing a PTC-resistor device

The invention relates to an apparatus for limiting an electrical current by using a PTC resistor being monitored by a monitor circuit. According to the invention, the monitor circuit issues a signal only after detecting the status of the PTC resistor for a defined time period after a PTC resistance change.

Apparatus for limiting an electrical current

A fuse has a fuse element ( ), composed of silver, with constrictions ( ) which follow one another at regular intervals, and which fuse element makes contact with a combustible element ( ), preferably over its entire length. The combustible element ( ) is composed of a combustion compound, which is essentially of a fuel such as guanidine or a guanidine derivative and a metal such as Mg or Al and an oxidant such as KNO , NaNO , NH NO , KClO , NaClO , KMnO , the proportion of which is overstoichiometric by a factor of at least 1.1, and preferably of at least 10. The combustible compound also preferably contains a binding agent such as paraffin, a thermoplastic or an elastomer, so that it can be extruded. It has an ignition temperature of between 160&deg; C. and 260&deg; C. and emits more than 200 J/g of heat, so that it ignites even in the event of small overcurrents and melts the entire length of the fuse element ( ).

Fuse with overstoichiometric amount of oxidant

The invention relates to an electric device with a PTC polymer element having a constriction. The constriction defines a web extending in a main current direction over a length longer than in the prior art, namely longer than 5 mm, preferably longer than 15 mm. Further, the aperture angle of the PTC polymer material at the ends of the web is larger than 100&deg;. A preferred choice of material is given, further. The invention achieves very high voltage-withstand capabilities.

Electrical device comprising a PTC polymer element for overcurrent fault and short-circuit fault protection

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.

Protective element

A description is given of a PTC polymer element (,) as part of an electrical component with a novel structure in which aperture angles (&agr;) on both sides of constrictions (,) in the PTC polymer material are at least 100&deg;. As a result, an improved response behavior can be achieved, and, in connection with further features, the construction of PTC polymer elements which are more rapid, capable of carrying greater currents and have higher dielectric strengths is possible.

Electrical component with a constriction in a PTC polymer element

The resistor body of a nonlinear resistor element having PTC characteristics includes a pulverulent first filler, whose material, e.g. TiB.sub.2, TiC, VC, WC, ZrBr.sub.2, MoSi.sub.2, has a specific conductivity of at most 10.sup.-3 .OMEGA.cm and in which the particle sizes are between 10 and 40.mu., and also, in order to improve the voltage sustaining capability by extending the switching zone and to achieve uniform energy absorption, includes a likewise pulverulent second filler having varistor characteristics and particle sizes between 50 and 200.mu., whose specific resistance at field strengths .gtoreq.2000 V/cm such as occur in the switching region of the resistor element and above, is at most 50 .OMEGA.cm, preferably at most 15 .OMEGA.cm, the fillers being embedded in a matrix made of a thermoplastic, in particular HD polyethylene or a thermoset. The average particle size of the second filler should exceed that of the first filler by a factor of from 2 to 5. A potentially particularly suitable material for the second filler is SiC doped with Al, B, Ga, In, N, P, As, as is similarly doped ZnO.

Resistor element

The current-limiting resistor has two connection electrodes (1, 2) which are arranged parallel to one another as well as a resistance body (3) which has PTC behavior and with which large-area contact is made by the connection electrodes (1, 2). A varistor (40) is in electrically conductive contact with the resistance body (3). The resistance body (3) contains two contact areas (50, 51) as well as a response point (60) which is connected in parallel with the varistor (40) via the two contact areas (50, 51) and implements a PTC transition above a threshold value of a current flowing through the resistor. Since the resistance body effects the electrical contact with the varistor (40) in the case of this resistor, no metal connection electrodes are required for the varistor. At the same time, due to the outward displacement of the response point (60) away from the varistor (40), the operational reliability of the resistor is considerably improved. Effective current limiting in load circuits which are operated at high voltage can be achieved by a series circuit formed by a plurality of varistors (40, 41, . . . ) provided in a resistance body (3) which is designed in the form of a meander or is of some other continuous design.

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Baden, Switzerland

Joachim Glatz-Reichenbach