DE527489C - Single-phase induction motor with capacitance connected in series with the auxiliary phase - Google Patents

Description

Single phase induction motor with series connected to the auxiliary phase Capacity single phase induction motors with auxiliary phase are often given for improvement the start-up and running conditions a capacity connected in series to the auxiliary phase. This capacity is dimensioned so that the most favorable possible efficiency at nominal load is achieved, with a multiple for the start-up to achieve high tightening torques the capacity required for the run must be used.

The purpose of the invention is now to make the very inconvenient and expensive additional To reduce start-up capacity, so as to reduce the cost of such an arrangement to make it economically viable. It is well known that economical capacitors are obtained if you choose their voltage up to a maximum of 25o volts, because you then use simple paper-paraffin dielectrics can get by and in this case no expensive evacuation processes on the capacitors must be made. The voltage at the terminals of the capacitor is at given mains voltage on the inductance of the auxiliary phase and on the size of the Capacity dependent.

The voltages on the auxiliary phase and on the capacitor add up vectorial and result in the sum of the mains voltage. Becomes the number of turns of the auxiliary phase kept constant, then the voltage at start-up, i.e. in a short circuit, reaches a larger value, corresponding to the conductivity of the scattering paths. Increases during the run this voltage, assuming constant capacity, due to the relieving influence of the rotating cage.

By selecting the number of turns of the auxiliary phase accordingly during start-up their voltage can be measured so that the capacity as economical specified limit voltage of about 25o volts. This gives you the cheapest Capacitor. The number of turns must now be reduced for the run, namely so far that now the specified limit voltage is applied to that for the most favorable running conditions calculated capacity, which is generally different from that required for start-up is.

According to the invention, this should be done by switching from series to parallel connection all or part of those divided into a corresponding number of groups Windings of the auxiliary phase winding are effected.

Fig. I shows, for example, a circuit diagram of the arrangement according to the invention. The main phase is denoted by a, which is divided into two groups with auxiliary phase b, and bli. With the switch d , the row or. Parallel connection of the groups; the capacitor c is always in series with the auxiliary phase. e is the squirrel cage.

If the starting torque is to be large, this is done in a known manner a larger capacity than required when running. It is then expedient to subdivide the capacitor according to Fig. 2 in cl and c .. Now are starting up with series connection of the two winding halves bi and bil of the auxiliary phase the capacities cl and c_ effective, 'in the run, d. H. if b, and b, 1 are connected in parallel, the capacitance c, alone. g is a correspondingly high bridging resistance of the capacitor c_, to accelerate its discharge after a shutdown. The other names are chosen analogously to Fig. i. The switching process itself can be known per se Way can be effected by means of a centrifugal switch or current-dependent relay.

Claims (2)

PATENT CLAIMS: i. Single-phase induction motor with to the auxiliary phase in Series of switched capacitance, characterized in that all or part of the Winding phases of the auxiliary phase winding in series during start-up, in contrast during operation are connected in parallel. 2. Single-phase induction motor according to claim i, characterized in that that the capacitance is increased during start-up by connecting an additional capacitor is.