SU1332414A1 - Method of checking the quality of fuses - Google Patents

Abstract

The invention relates to electrical engineering, namely to fuses. The aim of the invention is to provide automation and increase reliability of quality control of fuses (PP). According to the proposed method, a calibrated short-term current pulse is passed through the PC, the value of which exceeds the nominal current of the PC. The use of short-term current pulses, the magnitude of which exceeds the nominal value, ensures the speed of the control operation G1 and low energy losses and creates a heating of the fusible element sufficient to detect manufacturing defects of PP elements in the form of increased resistance PP. To ensure reliable measurement, in which the damage of fusible elements is prevented, the Joule integral of the current calibration pulse must be 3 to 5 times smaller than the Joule melting integral for a given current pulse. According to the proposed method, the value of a short-S temporary calibrated pulse is chosen 9–10 lu. 2 hp f-ly. (L: o y.

Description

The invention relates to electrical engineering, to the field of low-voltage apparatus, in particular to fuses g

The aim of the invention is to provide automation and hopefulness; quality control of fuses.

According to the proposed method for monitoring the quality of fuses, it is proposed to pass a calibrated short current pulse through the fuse, the value of which exceeds the nominal value of the current of the fuse. Supply of a calibrated current pulse, i.e. current pulse of a certain size, greatly simplifies the measurement process and, together with the use of a reference fuse, provides high measurement accuracy if, even when measuring different batches of fuses, the calibrated current pulses differ somewhat from each other. The use of short current pulses, the magnitude of which exceeds the nominal value, ensures fast control operation of the fuse and low energy loss, and also creates heating of the fusible element, sufficient to detect defects in the manufacture of elements in the form of increased resistance of the fuse. For example, a PP59 fuse on A, U 660/460 V, with a current pulse of I 10, A melts behind Yuma,

and at, A - in 20 ms. To ensure reliable measurement, which prevents damage to the fusible fuse elements, the Joule integral of the calibrated toKa pulse must be at least 3-5 times smaller than the Joule melting integral for a given current pulse. In relation to the considered example, the Joule melting integrals with a rectangular current pulse are equal to 160 × A s for 1 .. 10 I., and 260

 with at

-n

and integrals

The joule of the calibrated current pulse for measurement should not exceed (35-55) 10 A s and (55-85) s, respectively. Since the theoretical value of the Joule fusion integral for this fuse is

W € „. 103 Q 2

P

 2040-A2-c.

0

five

0

five

0

Where

Wn CM is the theoretical melting integral;

Meyer's constant; S is the cross-section of the necks, the integral of the square of the calibrated current pulse over time must be within

 75 - 25 20 "20

If the integral of the square of the calibration current pulse in time will be less than the specified values (35-55)

However, there is a danger that in some cases the fusible elements will not get warm enough and the defect may not be detected.

The use of current measurement pulses of 9 and 10 1, is due to at least two reasons: the need to shorten the duration of the test process and, therefore, reduce the duration of the current pulse; and the need to simplify the measurement process by applying a sufficiently large current pulse to a small ohmic resistance so that the resulting voltage drop can be recorded simply and accurately.

The calibrated current pulse used in the measurement may have a different shape. The most convenient, in terms of the simplicity of the equipment required and the control operation, are the sinusoidal (half-wave), triangular and rectangular shapes of the calibrated current pulse

The conclusion about the quality of the manufacture of the fuse based on the results, comparing the voltage drops on the reference and test fuses, is based on the following. The requirements of the technical specifications for the value of the deviation of the resistance of the fuse (or voltage drop) are taken into account. These requirements are more stringent when fuses are designed to work in parallel with each other; in this case, the deviation does not exceed 5% of the nominal value (on the reference fuse) o If the fuses are not intended for parallel operation.

313

the deviation from the nominal value may be 10%.

Reliability requirement is taken into account. Usually, when several necks are destroyed during the manufacture of fuses, the voltage drop may deviate from the nominal value by 15-20% or even more. Depending on the specific conditions, in most cases a more stringent requirement should be chosen corresponding to the deviation of the voltage drop from the reference within 5 -ten%.

Claims (3)

Invention Formula 1 o A method of controlling the quality of fuses by passing an electric current through them, determining the voltage drop across a fuse and comparing this value with a reference one, so that, in order to provide automation and increase the reliability of control, the electric current the form of a calibrated short pulse, the value of which exceeds the nominal value, and the integral of the square of this current pulse over the time of flow through the fuse is set to 3 Compiler S. Gordo Mr. Editor L.Gratillo Tehred L.Serdyukova Proofreader M.Demchik Order 3841 / A9 Circulation 697 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, Projecto st., 4 four 5 times smaller than the melting integral of the fuse with a current equal to the value of the current of the calibrated pulse, is fed to the reference fuse and at the time of the end of the flow of the specified electric current the voltage drop across the reference fuse is measured, after which the tested fuses are alternately inserted into the same circuit , 2. A method according to claim 1, characterized in that the magnitude of the short-term calibrated current pulse is chosen 9-10 1 c where IH is the rated current of the fuse. 3. The method according to paragraphs. 1 and 2, which is based on the fact that the integral of the square of the current of the calibrated pulse over time is selected within 1.75–4.25 of the theoretical integral of melting where W is the theoretical melting integral; C, y - Meyer's constant; S is the total cross-sectional area of parallel-connected areas of the weakened section.