DD106901B1 - Circuit arrangement for the synthetic testing of switching devices - Google Patents

Description

629-1-

The invention relates to a circuit arrangement for the synthetic testing of switching devices by means of high-current LC and high-voltage LC circuits.

The direct test is known for ITS switchgear, in which the switching capacity at full operating voltage, 3-pole, is tested on the grid »

Disadvantage of this circuit arrangement is the complicated setting of the parameters of the return voltage, if by the construction of the test rig hard Prüfbedin- conditions to be achieved.

Another disadvantage is the difficult synchronization of the test switch with the mains frequency,

_г _ 167 629

Another known method for testing switchgear is the synthetic! Test that is used in high-voltage circuit breakers _s Although you may only be a single-pole testing of the switch or switch part, but allows a simple variation of the test parameters of interest "

For this purpose short-circuit generators or high-current transformers or else capacitor batteries are used as high-current sources in the high-current circuit.

The well-known Gorew circuit sees as a high current source a capacitor battery ^v _o r _o It ^is ^ seen ^{from the} system cost her cheaper than a short circuit generator · In both types, a sinusoidal test current is generated at mains frequency in the rule.

However, the use of short-circuit generators also permits the generation of half the mains frequency or rectified sine-wave at a time «

In order to form the circuit of the high current circuit, when using a two parametric binoscillation voltage, it is necessary to connect a short circuit generator to a short circuit of a short circuit. However, this RÖ part is important only with respect to the recurrent voltage of the generator with respect to the transconductance and frequency of the transient voltage of the test circuit.

The synthetic test circuit in both examples consists of a high voltage and a high current circuit; the single ones. Circuits deviate from one another in their structure »According to Gorew, the" high-current circuit "consists of an LC circuit, while the high-voltage circuit, which lies parallel to the test switch, is made up of C or RC elements for varying the return voltage.

The disadvantages of the Gore ^ -Kreises consist in the fact that in the three-phase system of the first extinguishing Schalterpol is claimed only with a maximum of 3.33 ms arc duration.

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The 3Orm of the arc current is part of the sine half-wave, namely between 120 ° and 180 °. The full 50 Hz test current half cycle is therefore not required «

In order not to overstrain the test object, the switch contacts would have to open only at sin 120 ° of the test current half-cycle at the earliest. As a result, the expenditure on L and C switching elements becomes unnecessarily high or they are used uneconomically.

The object of the invention is to find a synthetic test method which allows an application of the G-orew circuit for the ШЗ-switching capability test while reducing the cost of components and which further allows a very good simulation of the ratios of the current zero crossing in the test switch.

According to the invention, the object is achieved in that the high-current circuit is formed from two parallel current sources which - зе arranged in a parallel LC and RC current branch - decoupled from each other by the diodes and charged to different voltages, the ratio equations

1 "for the first extinguishing pole

U ₁ c _{2 β} 1

RC,

2 ** ₃

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2. for the last extinguishing pole

, ^ ₂ C ₁

apply ©

The goal part of such a circuit is that the testing of the switching capacity of HS and LV switching devices is possible, reduces the complexity of components and to realize a very good replica of the conditions of the current zero crossing in the test switch. "The simple is still advantageous Dimensioning of the test circle *

Another aspect of the invention is that the RC part. consists of two or more parallel RC parts with different time constants «

The invention will be explained in more detail below using an exemplary embodiment »In the accompanying drawing show

Pig. 1 the synthetic test circuit, Pig. 2 the current flow in the high circuit.

The high circuit consists of Pig. 1 from the LC and RC part with the two current sources C and С ". The LC part is made up of the components C ", L and D ₁ , the RC part of C _? , R and Dg formed This high-current circuit is connected to the test switch Sp via the drain switch S ^ designed as a trigger spark gap.

- S-

U7 629

The capacitors C ₁ , Cp have different charging voltages. Furthermore, Fig. 1 shows the high-voltage circuit known from a synthetic test circuit, which has been shown for the sake of completeness and which consists of the elements R 1, C, C, Lp, FS and St.

The mode of operation of the high-current circuit designed according to the invention is explained on the Stromoszi.llogramm according to FIG. Curve 1 shows the required extinguishing switch pole in the three-phase current system, the required maximum test stronu The Gorew circuit L, C ₁ , which is dimensioned for the length of this strobe pulse, requires smaller components L ₁ , C- because of the approximately threefold Metz frequency Gorew circuit supplied current forms the basis for the synthesis of the required test current (curve 2 in Figo 2). The difference between the required test current 1 and the Gorew current 2 is shown in curve 3. It corresponds approximately to an exponent ion current pulse, γ / he is supplied by the present invention inserted RC part of the high current circuit of the second current source Cp and the associated damping resistor R. , The components R, Cp of the high-current circuit differ fundamentally from R., C, the high-voltage circuit and resulting from the known explosion protection for the capacitors of the Gorew circuit RC groupings _e To realize the required PrüfStromverlaufes the components C, Cp, L ₁ and R and the charging voltages U ₁ , XL · are in a certain relationship to one another «To create the conditions of the first-quenching pole in Drehstrcmsystem must. be fulfilled

167 629

For the conditions of the last pole

Ji * (2 ... 2,7). Jl.

^U 2 · ^C 1

JCt · Oa '/ &

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For decoupling of both parts R, C ₂ and L, C ₁ , a diode is required in each case, which is provided in the L., C ₁ part, when the conditions of the first-erasing Schalterpoles au create (Up> Uj |, and in R If the test conditions of the last-clearing pole are to be realized, L <(Up). Diode D ₁ furthermore has the advantage of keeping the test current from the test switch Sp after the current zero crossing and thereby supporting the deletion process of the push-button switch S.

Claims (2)

167 629 - * - claims: 1 · Circuit arrangement for the synthetic testing of switching devices by LC high current and high voltage circuit, characterized in that the high circuit consists of two parallel current sources (Cl, C2), each in a parallel LC-current branch (Cl, Ll, Dl with charging voltage Ul) and RC current branch (C2, R, D2 with the charging voltage U2) are arranged and charged to different voltages (Ul, U2) and the time constant of the RC current branch is about one sixth of the oscillation period of the LC current branch · » 2. Circuit arrangement according Anspruchl, characterized in that the RC part consists of two or more parallel RC parts with different time constants. - For this 2 sheets drawings -