SU834537A1 - Device for measuring coll inductivity - Google Patents

Description

one

The invention relates to measuring parameters of electrical circuits and can be used to measure the inductances of coils in examining circuits and checking measuring equipment in public metrological organs.

I-isBecTHbi devices for measuring the parameters of electrical devices in the form of bridges, compensation and resonant circuits.

A four-shouldered bridge is known, in which an example capacitance with a resistance connected in parallel is connected to an arm opposite to that with measurable inductance, and the non-reactive model resistors 1 are included in the other two arms.

Four-shoulder bridge circuits using constant-capacitor capacitors and variable resistances in their shoulders have poor convergence at low values of the quality factors. The process of balancing becomes difficult, bringing the bridge into a state of equilibrium is practically impossible.

Closest to the proposed technical entity is a device for measuring the coil forces, which contains a harmonic voltage source, a test coil, a sample resistance box, a sample resistance and a reference capacitance, two-input bridge equilibrium indicator {2}.

To simplify the process of balancing the bridge, the bridge is first balanced at a constant current by adjusting one co-resistance, and then at a variable current by varying the resistance value.

Claims (2)

The disadvantages of the known devices are the multistage and duration of the process of balancing ac bridges and the influence on the process of balancing the non-sinusoidal voltage of the power source. Thus, the measurement process of the inductances of the coils by bridge devices is associated with the need to balance the bridge, which makes the whole process of measuring the duration and multistage. Improving the convergence of the bridge by moving from a four-armed to a six-shoulder bridge complicates the device, increases the effect of interference and the magnitude of the measurement error. The purpose of the invention is to improve the accuracy and reduce the measurement time. The goal is achieved by the fact that a device for measuring inductances of coils containing a voltage source connected in parallel to two parallel branches, one of which is formed by series-connected inductors and a magazine of sample resistances, and the second are connected by a sample capacitor and resistor, and the indicator , one stroke of which is connected in parallel to the exemplary resistor of the second branch, the second input of the indicator is connected in parallel to the store of reference resistances first branch. In addition, the voltage source is made in the form of a generator of rectangular pulses. The drawing shows the electrical circuit of the proposed device. The device includes input terminals 1 and 2 for connecting a source of periodic rectangular voltage pulses, output terminals 3 and 4 for connection with the coil under study 5, a store of 6 exemplary resistances, an exemplary resistor 7, an exemplary capacitor 8 (indicator 9 with two inputs. Studied The inductance coil 5 has the parameters — the active resistance f and the measured inductance L. The device’s electrical circuit is a circuit with two parallel branches (rjj-Uy-R and CQ§-T) whose time constants are respectively The device operates as follows: A periodic voltage of a straight coal form is applied to the input of the device (terminals 1 and 2), which causes repeated transient orgly repetition of two transient processes in circuit 74 - switching on the circuit for a constant voltage followed by a short circuit. In the branches with inductance and capacitance, the I1 transitions change, exponentially varying with time constants, respectively. At a certain and unambiguous ratio of the parameters of the electric circuit 1, bo, T, Oo5 and T, by changing the resistance value T of the magazine 6 exemplary resistances, we obtain the equality of the constant time of the inductive and capacitive branches ° C, which allows the indicator to determine the time equal to equal time. the measured inductance by the known Ostaping parameters of the circuit T, Co5i and R {the active resistance of the coil is assumed known or previously measured (HHbnvf), Then from the equality (l) of the inductance .-S5. An indicator of the equality of the constant times of the parallel branches of the circuit is an ecc electronic oscilloscope (indicator 9), to the vertical input x of which is connected the transition voltage from the resistance store 6, proportional to the transition current 1c inductance, and to the horizontal input - voltage from the resistor 7, proportional to current -ij of the reference capacitor 8. On the oscilloscope screen, before adjusting the circuit, an image is obtained in the form of two curved lines, one of which corresponds to the switching process to a constant short circuit and the other short circuit. After the setting of the chain of the pr, C0, the curves of the phase trajectories turn into straight lines inclined at a certain angle to the axis. The ability to adjust the circuit by changing only the value T of the magazine 6 exemplary resistances greatly simplifies the device and its operation and significantly reduces the measurement time. The functional dependence of the measured inductance on the parameters of the measuring circuit (2) is (more typical than the known devices, which gives a smaller error in the measurement method. In addition, due to the simplified setup of the circuit, it decreases to the accuracy of measuring interference from additional links separate elements. The use of depiols with two parallel branches in a new combination with the indicator allows in TpEs-four times to reduce the measurement time and several times to reduce the cost of comparing with the existing Thus, the indicator indicator 9 is additionally supplied with a second input (Y and connection of one terminal to the second output of the exemplary resistor 7 and a plate of the reference capacitor 8, combining the other terminal (Y). of the indicator 9 with the terminal of its first input (X) and input terminal 2 provides a simplification of the device, improving its accuracy and reducing the time to obtain measurement results. Formula 1. A device for measuring the output of coils, containing a voltage source 76 connected in parallel to two parallel branches, one of which is formed by series-connected inductors and magazine model resistors, and the second - by series-connected samples and a capacitor and a resistor and an indicator, one input of which is connected in parallel to the model resistor of the second branch, characterized in that, in order to improve the accuracy and reducing the measurement time, the second input of the indicator is connected in parallel with the store of exemplary resistances of the first branch. 2. The device according to claim 1, wherein the voltage source is made in the form of a generator of rectangular pulses. Sources of information taken into account during the examination 1. Karpov R. G., Karpov M. R. EectroIzmereni. M., Higher School, 1978, p. 137. 2. Gavrilyuk M. A. Four-shouldered bridges of alternating current, Lviv, Higher School, 1975, p. 38 GM