SU107437A1 - Zero indicator to bridge or compensatory measuring devices of alternating current - Google Patents

Description

In the electrical devices included in the compensation and bridge circuits, various zero indicators are widely used. However, the indicators of known tins do not allow for a rigorous measurement of the even and odd harmonics of the components of the non-temporal voltage curve, which is very important in the study of electromagnetic processes in chains with steel.

To measure these high harmonics, it is proposed, according to the invention, to connect an indicator meter (galvanometer) to a transformer connected to the output of the meter through a system of two or three rectifiers.

The drawing shows a schematic diagram of the proposed indicator.

A COJ: TOHT device from a transformer with one primary 1 and two secondary windings 2 and 3, a magnetoelectric galvanometer 4, and a full-wave rectifier 5 and 6 fed from a phase rotator 7. The transformer turns on the output of the measuring device (for example, the diagonal of the measuring bridge), due to which the test current flows through its primary winding.

If it is necessary to measure the odd harmonics, the secondary windings 5 and J of the transformer are connected to the galvanometer 4 in parallel and oppositely (by means of switches 8 to 9) through contacts of an ignition electrode rectifier 5 and 6 are connected in series and counter.

The contacts of both rectifiers 5 and 6 are adjusted to a cut-off of 180, therefore, during operation of the device, the contacts of the rectifier 5 are closed for one half of the period, and the contacts of the rectifier 6 are closed during the second half of the period.

No. 107437

Galvanometer 4 supplies the difference in voltage between the two secondary windings of the transformer, due to their antiphase switching on.

Due to the fact that with such switching on, the voltage curves with even harmonics acting in both secondary windings of the transformer are mutually compensated, the deviation of the galvanometer at the time of unbalance is due only to a curve with odd harmonics.

If it is necessary to measure even harmonics, the secondary windings 2 to. 3 transformers are connected to the galvanometer in parallel and agreed, moreover, an additional controlled rectifier / () is connected to the galvanometer circuit between the midpoint of the coils 2 and 3 and the rectifiers 5 and 6.

The excitation winding 10 of the rectifier is powered by the phase shifter 11, and its contacts are adjusted to a cut-off of 90 °.

Due to the fact that the secondary windings of the transformer with respect to the galvanometer are connected in a coordinated manner, the galvanometer 4 at the time of imbalance applies the total voltage of both windings 2 and 3 of the transformer. Therefore, the deviations of the galvanometer are proportional to the voltage curve with even harmonics.

The excitation windings of the controlled rectifiers 5, 6 to 10 can also be powered from one phase shifter.

Subject invention

A zero indicator to bridge or compensatory measuring devices of alternating current, containing a transformer with two secondary windings, connected to the output of a measuring device, rectifiers and a galvanometer, characterized in that, in order to separately measure the even and odd harmonics of the components of the alternating voltage curve the compensation circuit, the secondary windings of the transformer are connected to the galvanometer in parallel and in accordance with the measurement of even harmonics or in parallel and counter to it when measuring not etnyh harmonics through odnololuieriodnye controllable rectifiers operating in opposite phase with the frequency of the supply voltage, and through an additional rectifier introduced into the circuit when measuring the even harmonics and zamykayuschly chain talvanom .etra within each quarter period naedites supply. wives

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