SU378779A1 - METHOD OF MEASURING THE COEFFICIENT OF THE ASYMMETRY OF THREE-PHASE ELECTRIC NUTRITIONAL NETWORKS - Google Patents

Description

I

The design refers to the measurement methods of electrical magnificence, namely, the measurement of the ac1MM1etr: AI and IB three-phase electrically | network | X, and can be used when working: from inpiHi5oipOB to measure the asymmetry coefficient (electrical supply networks).

The known methods for determining the asymmetry factor of three-phase electric 1X supply networks consist in measuring the voltage (or current) of the direct reverse sequence and comparing the value of the asymmetry factor to the formula:

I arr.

but

(J

etc.

where a is the asymmetry coefficient of the three-phase network; arr. - the voltage of the first sequence; Unp. - Voltage 1Pr m OY;

However, such methods can be used to calculate the CoE | fcience1T ACI1M1Metria only from measurement data, and not directly.

To simplify: I measure, e | i ni. Asymmetry coefficient to the network under test are connected to a three-phase asynchronous electrodigger

AOM2Sh type 42-6, w. which transform the asymmetry of -CHiCTeMbi of the supply voltages (currents) IB vibration acceleration. When measuring, the electromy works in idle mode. The rheostats are included in two phases to control the amplitude of the respective phase voltages. D | c. The fixture is suspended on two parallel-connected shock absorbers of the type AKPO-4 horizontally with its paws down. The vibration sensor, a gesture fixed to the engine foot from below, has a radial component (VI1brow | Speedy).

With the asymmetry of the mains on the phase

The stator windings of the wigatel electrode flow through the reverse coherent currents, which create a magnetic flux of the reverse sequence, which sharply increases the vibration level of the electric motor at a frequency,

numerically equal to the second harmonic of the network frequency.

The vibration acceleration of the electrode of the vigatel is converted by a vibroscopic into an electric generator.

From the total vibration signal of the sampler with the help of the knots of the Kopolos filter, the component is selected with a frequency that is equal to twice the frequency of the power supply network, and it is recorded on the scale of the instrument, which is derived from

YES - a,

where a is the asymmetry coefficient of the emitting network;

x is the orient of the constituent vibrating component with frequency, numerically p. double the frequency of the mains;

a and and - 1 constants characteristic of a given type of asyncroy electric motor.

Subject invention

Gnoico6 and the asymmetry coefficient of three-phase electrical supply networks, characterized in that, in order to simplify the measurement, an asynchronous electric motor is connected to the experimental network, in which the asymmetry of the power supply system (TOKOIB) is converted into vibration acceleration, is separated from the vibration spectrum of the electric motor frequency, which is numerically equal to the doubled frequency of the mains supply, and recorded in the asymmetry coefficient values, taking into account the dependence of

and 10 a - the coefficient of asymmetry n-itayue

your network;

x is the increment of the component acceleration with a frequency that is numerically equal to twice the frequency of the supply network;

and w b - constants characteristic of this type of asynchronous motor.