SU1430923A1 - Method of determining attenuation coefficient of seismometer - Google Patents

Abstract

The invention relates to technical physics and can be used in seismometry, seismic exploration and geophysical instrumentation, as well as in areas of technical physics that use magnetoelectric devices. The purpose of the invention is to simplify the method of determining the electromagnetic attenuation coefficient while simultaneously reducing the detection time, which is achieved by determining the electromagnetic attenuation coefficient by applying a direct current to the seismometer coil and then opening it as the ratio of the first amplitude of the voltage at the coil output after opening to - double the value of the current passing through the coil before opening. 1 il. iS (L

Description

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WITH

about; about to

with

The invention relates to technical physics and can be used in seismometry, seismic exploration and geophysical instrumentation, as well as in areas of technical physics that use magnetoelectric devices.

The purpose of the invention is to simplify the method for determining the electromagnetic attenuation coefficient while simultaneously reducing the detection time by eliminating vibration records, attenuation determinations, and measuring the resistances of coils and shunts.

The implementation of the method is based on the analysis of the form of the initial voltage of a magnetoelectric seismometer when it is excited from an electrical side by a constant current i with a duration exceeding the duration of the transient process:

-E-b

sinco.-t, (1)

E (t) E „e

where - attenuation coefficient iiy - angular frequency of visible

fluctuations. The factor E for progressively

about

seismometers is:

 SU ° Mm

and for rotational, 0 kb.

S is the sensitivity of the transducer, In C / m;

G is the magnetoelectric constant, В «с;

M - mobile inert mass, kg;

K - moment of inertia relative to

rotation axis, kg.m. For a known rotational seismometer

but

G2 2KQ

for the regime of undamped oscillations at –O and ω, –CO

and E / 2i,

where E is the amplitude of undamped oscillations.

(five)

sleep ekv ot Q

Oi ri to- 20 e1) 25

thirty

2)

3)

g;

35

40

45

from (4) 50

ri

five)

55

In fact, for serial seismometers with air attenuation of the order of 0.01, the error in determining the coefficient a, without taking into account the lateral attenuation, estimated by the formula (5) does not exceed 0.25% for the first amplitude, 0.5% for the second.

The drawing shows one of the possible schemes for implementing the method.

The circuit contains a seismometer 1, a direct current source 2, a switch 3 for closing and opening one coil and a switch 4 for switching on and off the current of the second coil, a current meter 5 and an amplitude voltage meter 6. The circuit can be supplemented with a computing device to solve formula (5).

The method is carried out as follows.

Switch 3 closes one coil of the seismometer, toggle switch 4 turns on the current to another and measures its value with a current meter 5, opens switch 3, turns on the current with a toggle switch 4 and measures the amplitude voltage of the first non-damped voltage meter.

Claims (1)

The advantage of the proposed method is the simplicity of its implementation and efficiency, which allows to obtain the desired parameter more than ten times faster than the prototype method, according to which repeated photo-recording, appearance, drying and processing of results in continuous and damped oscillations are necessary. The proposed method is convenient when frequent and repeated adjustments are necessary and when determining the coefficient using magnetic shunts, for example, when solving problems of field and engineering seismometry. The method is also applicable for calibrating magnetoelectric devices in technical seismometry of industrial vibrations. Invention Formula The method for determining the electromagnetic damping coefficient of a seismometer, which includes the supply to its coil of an impulse of electric current with a duration exceeding the duration of the transient process and measuring the amplitudes of undamped oscillations, characterized in that in order to simplify the method while reducing the time of determination, close one of the coils of the seismometer, supply direct current to the other coil, measure the current i, open the closed coil. turn off the current, measure the voltage of the maximum of the first amplitude of oscillations E at the output of the coil to which current i is applied, and determine the coefficient of electromagnetic attenuation a by the formula a E / 2i.