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Motor capacitors of LLC Nucon production of k78-98 series are intended for connection to windings of the asynchronous electric motors getting their power from a single-phase network with frequency no more than 60 Hz, and also for transfer of three-phase engines to power from a single-phase network

Recommendations for choosing the type of capacitors for asynchronous motors

During the operation of the motor current flows through the winding, 20-40% higher than the nominal, therefore, when using the electric motor in underloaded mode or in idle mode, the capacity of the working capacitor should be reduced.

For safety reasons, all starting capacitors must be used with a discharge resistor. The resistance of the discharge resistor is selected so that after 50 seconds to remove the residual voltage from the capacitor completely.

In cases where the capacitor is used in a series circuit with an auxiliary motor winding, the voltage at the terminals of the capacitor at the operating speed can be much higher than the mains voltage.

During operation of the capacitors, they can be installed directly in physical contact with the motor. In this case, when choosing the type of capacitor, it is necessary to take into account that the capacitor will be exposed to high temperature and vibration - both from the motor itself and from other passive elements of various devices, in which the capacitor will be used.

When operating, motor capacitors have different kinds of complex switching processes, which result in abrupt changes in the voltage at the terminals of the capacitor, and therefore the rated voltage of the capacitor must be selected so that in the process of operation of the product operating voltage does not exceed it by more than 10%.

In the process of selecting the required capacitance and operating voltage must be taken into account along with the resonance factor, that is, when the voltage of the auxiliary winding of the motor and the capacitor are in the near-resonance point. In this case, there is an increase in the voltage at the terminals of the product.

The limit voltage at the terminals of the starting capacitor should be no more than 450V, and its capacity is selected, as a rule, two or more times the capacity of the working capacitor.

As practice shows, for every 100 watts of motor power is required about 6-7 UF.

If it is not possible to pick up the capacity in the same housing, it is allowed to combine by parallel connection of capacitors Sobsch=S1+C2....+SP.

With a properly selected capacitor, the power of the three-phase motor included in the single-phase network should not be reduced by more than 30%.

Field of application of capacitors for asynchronous motors

Table: Field of application of capacitors for asynchronous motors
working launcher
Use In the circuits of asynchronous motors In the circuits of asynchronous motors
Type of connection in series With the auxiliary winding of the motor parallel To the working capacitor
As is the phase-displacement element
The purpose Allows to obtain a circular rotating magnetic field required for the operation of the motor allows to obtain a magnetic field required to increase the starting torque of the motor
Time of switching on in the process of electric motor operation at the moment of electric motor start-up