CS267070B1 - Condenser Warming Measurement Method - Google Patents

Abstract

The solution falls into the field of electrical measurements and concerns a method of measuring the heating of a capacitor, mainly electrolytic. The essence of the solution is that the dependence C = f (T) of the capacitance C of the capacitor on the temperature T in the interval from the minimum to the maximum operating temperature is measured. The measured capacitor, whose nominal voltage is Um, is acted upon by a direct voltage Ujs of a magnitude of 0.1 Um to 1.0 Um, on which is superimposed an alternating voltage Ustr of a maximum magnitude given by the relation |/2” bstr ~ ujs + 2, while the total measuring voltage Ujs + Ustr is less than or equal to Dm. Immediately after disconnecting the measuring voltage, the capacitance C of the capacitor is measured and the temperature T of the capacitor is read from the dependence C = f (T).

Description

CS 267 070 Bl

The invention relates to a method for measuring the temperature rise of a capacitor, in particular electrolytic, due to dielectric losses inside the capacitor.

Measuring the warming inside the capacitor is difficult due to its design. The surface temperature does not give information about the temperature conditions inside the coil due to the air gap and various capacitor construction materials, and moreover it is difficult to measure. A method is known in which a thermocouple or other thermal sensor is used on a model capacitor to measure the temperature rise. However, these sensors distort the temperature conditions in the capacitor because they contribute to heat dissipation.

These disadvantages are substantially eliminated by the method of measuring the capacitor warming according to the invention, which is based on the fact that, for a given type of capacitor, the capacitor capacitance C is measured in a temperature range from T. T, to correlate the C = f (T), wherein the capacity of the capacitor C ^t min max tora, the condenser temperature T, T. the minimum working temperature of the condenser and T '''is ^{J J t} min max maximum working temperature of the capacitor. Thereafter, a voltage U of 0.1 U to 1.0 0 is applied to the capacitor to be measured, whose nominal voltage is U, to which an alternating voltage U _{g r} of the maximum size given by | 2 is applied. U _g ^ _r = Uj _s + 2, the total measuring voltage ^U js ⁺ Ugt.. ^must ^ alkyl or less the same as in _m · Immediately after disconnection of the measuring voltage is measured capacity of the capacitor C and the temperature T of the capacitor is determined by the function C = f (T).

An advantage of the method of measuring the temperature rise of a capacitor according to the invention is that the actual mean temperature of the dielectric is determined without interfering with its design. Distortion of temperature conditions due to heat dissipation in thermocouples used up to now is avoided.

The process according to the invention is carried out as follows. For a given capacitor type, the dependence of capaity C on the temperature T of the capacitor is measured. The measurement was performed in a thermostat at the temperature range from the minimum operating temperature T _m ^ _n to the maximum operating temperature _Tmax condenser. T values. and T are determined from the catalog for each capacitor type. This gives a min max calibration curve, determined by dependence.

C = f

Thereafter, the capacitor to be measured is loaded with a measuring voltage consisting of a unidirectional voltage U of 0.1 U to 1.0 U, where U is the nominal voltage of the capacitor, and to our mmm ^{J of the} alternating voltage U _t , given by ΠΓ U. = U. + 2 * str are where the total measuring voltage U. + U. must be less than or equal to U. I.e., ^r lo p m the capacitor can blow a maximum of 2 M. After disconnecting the measuring voltage is directly measured capacitance C of the capacitor. From the calibration curve determined by dependence, the capacitor temperature T is determined, for example by subtraction, to the measured value of capacitance C.

Claims (1)

SUBJECT MATTER OF THE INVENTION A method of measuring the temperature rise of a capacitor, mainly an electrolytic one, characterized in that for a given type of capacitor by measuring the capacitance C of the capacitor in the temperature interval ^T m£ _n to T___ is the dependency detected C = f(T) CS 267 070 Bl where C = capacitor capacity T = capacitor temperature ^T min ⁼ minimum operating temperature of the capacitor ^T max ^{= max} i ^m ^l ^at the operating temperature of the capacitor then the measured capacitor, whose nominal voltage is U _m , is subjected to a DC voltage of 0.1 to 1.0 U^, on which an AC voltage U _gtr of the maximum magnitude given by the relation str is superimposed U . is while the total measuring voltage ^U js + ^u st _r ^must be less than or equal to U _m , immediately after disconnecting the measuring voltage, the capacitance C of the capacitor is measured and the temperature T of the capacitor is determined from the dependence.