Abstract: The single-phase induction motor has a starting device which is activated during the start-up phase of the motor and exposes at least a part of the motor coil to a voltage which changes temporarily, the average value of the voltage formed during one period of oscillation not being equal to zero.

Abstract: The centrifugal pump unit has a split tube motor in the form of a single phase induction motor with at least one power winding and a starting winding accommodated in a split tube casing. For the purpose of unblocking the rotor, a rectifier element is provided, which is able to be connected in parallel or in series with at least a part of a starter or power winding. The average torque produced by the motor when in its unjamming phase is always in the same direction, so that the pump will commence rotating in the correct direction when unjammed. The rectifier element may be connected in every time the pump unit is started, possibly for a predetermined time, or may alternatively be connected in only when jamming occurs.

Abstract: A pump unit especially for heat producing and heat distributing plant has an electric motor having a rotor which is sealed against the fluid conveyed by the pump unit. The electric motor which is cooled by the conveyed fluid drives a rotary pump for controlling the speed of the unit. Part of the stream of the conveyed fluid which is diverted for cooling the electric motor and the frequency converter, flows through a cooling jacket which receives the motor. The frequency converter is attached to the outside of the cooling jacket in heat conducting relationship therewith and the frequency converter and the motor are received in a common housing.

Abstract: The gas boiler is intended for room heating and producing hot water and has a gas-heated primary heat exchanger which feeds two heating circuits lying in parallel. The heat exchange medium is circulated via a rotary pump driven by an electric motor, arranged on the cold side of the primary heat exchanger and has a control mechanism which is arranged on the pressure side and controlled by speed or direction of rotation. This control mechanism serves to actuate a switch mechanism connected to the pump housing, in that it connects in series one or other heating circuit to the primary heat exchanger. The switch mechanism is arranged on the hot side of the primary heat exchanger in the pipework to the heating circuits.

Abstract: A method for taking samples from a groundwater monitoring site realized by measuring an electric conductivity of contaminated groundwater during operating a pump at high r.p.m. and by controlling a predetermined minimum variation of the electric conductivity over a predetermined period of time with subsequent operating of the pump at low r.p.m.

Abstract: The electric motor is provided with an attached frequency converter for rotational speed control. The frequency converter consists of a power supply and other electronic elements. While these electronic elements are arranged as a constructive unit with the electric motor, the power supply is arranged as an individual constructive unit separated from the motor, in the form of a module. The module can be made separately from the motor and electrically connected to the motor constructive unit through a connective cable. The use of the motor is no longer dependent on cooling radiators, required for the cooling of the power supply, as only the module is now fitted with cooling radiators.

Abstract: In the method proposed a peripheral wall with at least one axial section of high shaping and fitting accuracy is made by forming an initial blank. This accuracy is achieved, in that before the peripheral wall is formed, sheet material which has been put into a plastic state is swaged in places round the periphery, then the swaged locations are sized, and/or in that during or after the formation of the peripheral wall, the wall is shaped by stamping in a plurality of places along its periphery, whereby the said zone providing shaping and fitting accuracy is formed from fitting areas at at least one side of the peripheral wall in the region of the swaged and/or stamped locations. An apparatus for carrying out such a method is generally in the form of a drawing machine, wherein the holder and/or the bottom die contain radial apertures, which open into the inner edge of the holder and/or into the shaping cavity of the die, and which are arranged at intervals round the periphery.

Abstract: The pump unit is provided, in particular for heating and cooling installations. The speed of the pump unit may be altered by changing the operating frequency of a frequency converter feeding the electric motor and which forms a structural unit with the pump unit. As soon as the pump unit has reached a parameter characterizing the thermal overload of the same, the frequency converter is controlled in a manner so as to reduce the speed, the reduced speed n' being greater or equal to half the normal speed n.

Abstract: An immersion pump assembly comprises a pump and a wet-rotor motor driving the pump and having a common hollow spindle for the motor and the pump. Liquid in the wet-rotor compartment of the motor can be introduced into the spindle and conveyed within the spindle into the pump casing in heat exchange relationship with the liquid conveyed by the pump, by way of the wall of the spindle. The liquid is returned from the spindle into the rotor compartment by a pumping action. The exit and return openings for the liquid in the rotor compartment are spaced from each other axially of the pump assembly.

Abstract: A method for winding a stator that may be used for single-phase and three-phase motors. The stator windings are spread across several slots of the stator so that some of the slots receive winding portions of several phase windings. The windings are made by using a mandrel that has step-formed portions with a plurality of winding surfaces. Some of the winding surfaces lie in the same plane so as to permit the windings wound thereon to fit properly into the slots of the stator.

Abstract: An immersion pump assembly comprises a wet-rotor motor of which the rotational speed and/or the torque can be varied by means of a frequency changer, and a pump unit. The frequency changer, the wet-rotor motor and the pump unit are arranged one above another within a tubular jacket. The motor comprises a split tube formed as a closed pot which is connected to the jacket and which separates the stator compartment from the pump unit in liquid-tight and pressure-tight fashion. The frequency changer is so installed in the stator compartment that its operating electronic system is disposed on the bottom of the split tube pot in the stator compartment.

Abstract: The present invention relates to an electromotor where its operational values, such as speed and torque, can be changed by means of a static frequency converter. The invention relates further to an electromotor combined with and driving a working unit such as a pump, a ventilator a machine tool or a tool. The frequency converter miniaturized by means of a high-integrated circuit is mechanically connected to form a structural unit with the motor or the working unit, and the dissipation heat of the frequency converter is emitted, preferably by means of ducted cooling, and the metal parts surrounding the frequency converter form the electric shielding thereof.

Abstract: An immersion pump assembly comprises a pump and a wet-rotor motor driving the pump. The motor and the pump have a common shaft which is closable and hollow and which is partly filled with a fluid, for dispersal of waste heat from the rotor chamber of the motor into a heat sink provided by the liquid to be conveyed by means of the pump. The shaft together with the fluid constitutes a rotating heat pipe system.

Abstract: The invention relates to a static frequency converter in a housing, especially a frequency converter controlling and/or adjusting the performance data of an electromotor. The housing is shaped as a pressure-resistant casing sealed toward the ambient and at least partially provided with a filler serving as a heat conductor for the dissipation of heat to the surface of the casing.

Abstract: A multistage rotary pump, which comprises a substantially closed pump body having a jacket surrounding the pump body in spaced relationship for the purpose of forming an annular return volume, a base element comprising suction and pressure connecting pieces and a top element comprising the driving motor. The jacket is provided in both its terminal portions with a peripheral contact shoulder which is acted upon in each case by an annular clamping arrangement, the clamping arrangement in question being connected on the other hand to the base element and top element, respectively. A coupling device of this nature is preferentially applied in the case of in-line rotary pumps.

Abstract: A multistage in-line rotary pump which comprises a closed pump body, a base element provided with suction and delivery connectors, and a head element. The pump body is surrounded by a cylindrical jacket or casing spaced from the pump body to form an annular return space, which casing is clamped between the base and head elements by means of stay bolts. Flat joints are provided between the base and head elements and the respective axial ends of the casing. To prevent high areal compression stresses in the area of the flat joints, the two extremities of the casing are plastically deformed to obtain a wall thickness which is greater than the wall thickness of the rest of the casing tube.

Abstract: The inventive assembly comprises a driven feed pump fed with untreated water, and a water circuit connected thereto with a driven circulation pump and a reverse osmosis unit, wherefrom subsequent to the reverse osmosis treatment part of the water is available as pure water whereas the remaining part leaves the reverse osmosis unit in form of concentrated untreated water and is at least partially returned to the circulation pump.In order to render such an assembly more compact and less expensive in production the feed pump and the circulation pump are arranged on a common shaft driven by one motor.Such an assembly is preferably used in private homes.