DE1916560A1 - Compressed gas switch or compressed gas insulated switchgear - Google Patents

Description

BROWN, BOVERI & CIE · AKTIENGESELLSCHAFT MANNHEIM BROWN BOVERI

Mannheim, March 18, 1969 Pat M-ec.

Mp. No. "532/69

Pressurized gas switch or pressurized gas-insulated switchgear

The invention relates to a gas pressure switch or a Compressed gas insulated switchgear with a high and a low pressure part and a closed gas circuit in which the High pressure part via at least one switching section equipped with a blow valve and / or via a safety valve, that at a maximum permissible pressure in the high pressure part responds, is connected to the low-pressure part, and the gas return from the low-pressure part to the high-pressure part by means of one or more compressors takes place.

In such switches and switchgear, the switching points are located between the high-pressure part and the low-pressure part, which are blown during switching operations due to the pressure difference between the two parts. The low pressure part that the catches the outflowing switching gases, also serves to isolate the electrical system components. So it comes at such switches and switchgear on that.sowohl the pressure difference required for switching between High pressure and low pressure part, as well as those for maintaining the required pressure height or There are gas tightness in the low pressure part.

Since such compressed gas switches and switchgear are usually * considerable If temperature fluctuations are exposed, the pressure level of the gas changes according to the temperature or, if this is kept constant, it changes Density of the gas, which must be taken into account when dimensioning the insulation.

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There are several ways to take these relationships into account Pressure or density controls have been proposed, 'which are, however, quite expensive. For example, in the DAS 1 166 878 specified temperature-compensated pressure switch, via which the compressor is to be controlled, unfortunately only manufacture with considerable effort. Careful adjustment must be carried out so that the correct assignment of pressure and temperature is automatically guaranteed which takes a lot of effort.

For this reason, it has already been proposed to avoid the known temperature-compensated control switches by that one uses several temperature-independent working pressure monitors, of which depending on the temperature via one Thermostat one is made effective (DBP T 226 684) «, but this results in a multiplication of the number of Pressure monitor, so that effort and susceptibility to failure cannot be reduced to the desired extent «

Another proposal relates to the control of a compressed gas switch with a closed gas circuit and provides that the pressure-dependent locking elements required for the switch can be actuated by a temperature-independent pressure monitor in the high and low-pressure part of the gas circuit, with the two pressure monitors in their working areas as are set so that one records the critical values at high temperatures and the other at low temperatures (DAS 1 261 220). This arrangement is. but tailored to the special case mentioned. In addition, as in the previous proposal, it results in discontinuity. in the operating characteristics, which may be undesirable ₀

The invention is based on the object in electrical switching systems and gas pressure switches of the above type with the simplest means to extinguish the arc and to: Driving the switch necessary high pressure or the necessary Pressure difference as well as the low pressure necessary for the insulation, measured according to the required medium & tgasdiohte,

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to be provided and solely depending on the pressure levels to control so that the required minimum pressures are not below and the maximum permissible values are not exceeded.

According to the invention, this object is achieved in that the switches of the above-mentioned type have a buffer container in the gas circuit with increased pressure compared to the high pressure part, at which both the high pressure part and the low pressure part are above corresponding reducing valves are connected, and that the connected to the low-pressure part, solely on the pressure head in the low pressure part controlled compressor with its output is connected to the buffer tank *

To further explain the invention and its mode of operation, reference is made below to the drawing;

Show it:

Fig. 1 in a schernatic arrangement the gas cycle of the Switch or switchgear according to the invention. and

Pig. 2 is a diagram in which the pressure-temperature changes in the state of sulfur hexafluoride (SF 6) constant volume are shown with the preferred operating characteristics of the invention Switch or switchgear *

As can be seen from FIG. 1, the gas pressure switch or the switchgear S has a high pressure part HD and a low pressure part ND. A switching path with an associated blow valve Vg is arranged between the two, which during switching operations allows the gas from the high-pressure part to flow off via the switching path to the low-pressure part. Both the low-pressure part and the high-pressure part are each connected to a buffer tank P with a pressure higher than that of the high-pressure part _{via their own reducing valve V 1 or V 2}

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tied together. This limits the maximum pressure that occurs and the HP part can be dimensioned correspondingly weaker. The low-pressure part is connected via a further valve V _m and a filter Fi to a compressor K, which feeds into the buffer container P via a further filter Fi, thereby closing the gas circuit. The following safety measures are available: A safety valve Vj ₅ connected to the low-pressure part, a safety valve Vg connected to the buffer tank P and a reserve gas tank F, which is connected to the buffer tank via a further reducing valve V. In addition, the high and low pressure parts each have a standard pressure switch

and "W _2" provided.

The invention assumes that a certain minimum gas density '$ min (see FIG. 2) must be present in the low-pressure part in order to maintain the insulation. This minimum gas density is assigned _{a certain minimum pressure P min} for the highest temperature t to be taken into account. From this it follows that a lower operating pressure P ₁ must always be present in the low pressure, which is above the minimum pressure P _m j_ _n . This lower operating pressure P ₁ is made available at any time from the buffer tank P via the reducing valve V ₁ . ■

As a result of switching operations, temperature increases or also as a result of overcurrents? of the high-pressure part HD, the pressure in the low-pressure part ND increases. This is permissible up to an arbitrarily defined upper operating pressure P. If this upper operating pressure is reached in the low-pressure part, the compressor K responds, sucks gas from the low-pressure part and pumps it into the buffer tank P. This continues until a normal pressure P _{2 has been} set in the low-pressure part, which makes more sense - but not necessarily corresponds to a normal gas density f η at the highest operating temperature t _Q. The normal gas density Pn is the gas density that is present at the lower operating temperature t _u and the lower operating pressure P ₁ . When normal pressure is reached - '. sioh the compressor off again.

switches

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_{A sufficient pressure difference, which is determined by a minimum pressure level P 5} in the high-pressure part, is required for operational switching, i.e. for blowing the switching path arranged between the high-pressure part and the low-pressure part. This minimum pressure level P _K depends of course on the highest possible upper operating pressure P, in the low-pressure part, ie it must be sufficiently high compared to P, and is _{constantly kept ready by the reducing valve V 2} , via which the high-pressure part is connected to the buffer tank. For this purpose, the buffer container is set to a pressure level P ~ which must be sufficiently above a maximum permissible pressure value Pg of the high-pressure part.

As a result of a temperature change, e.g. from t to t could the pressure in the high pressure part increases to impermissible values, i.e. exceed the maximum permissible pressure value Pg. This too prevent, is the task of the safety valve V ,, that with reaching of the maximum permissible pressure value P ^ responds and that Gas can flow off into the low-pressure part. If this then leads to too great an increase in pressure in the depressed area '(exceeding of the upper operating pressure P,), the compressor punctures in the manner described above »

The additional security measures work as follows:

_{The safety valve V 1} - connected to the low-pressure part is set to a pressure P, which is above the upper operating pressure P, and ensures that in the event of a malfunction (e.g. failure of the compressor) the pressure in the low-pressure part cannot rise to excessively high values. The solenoid valve V closes the line leading from the low-pressure part to the compressor when the minimum pressure P _m | _{n is} reached, thus ensures that the compressor cannot suck off too much gas from the low pressure gas. That at the buffer

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The safety valve V ₆ connected to the tank P responds at a maximum pressure limit P _Q ■ which is permissible for the buffer tank and allows the pressurized gas to flow out into the open if necessary. And finally, an additional gas supply F, which via a reducing valve V ₄ , which is set to the nominal pressure P _{7 of} the buffer tank, ensures that any gas losses in the switch or in the switchgear can be compensated for.

The advantages achieved with the .Erfindung are in particular that the pressure levels necessary for extinguishing the arc and for driving the switch and the necessary pressure differentials as well as the low pressure necessary for isolation are provided with simple means, the pressure level in particular in the low pressure section as follows that the minimum gas density required for adequate insulation is present, without temperature compensation devices or gas density measurements having to be used to control the gas cycle. In the case of the invention, it is completely sufficient to control the compressor via a simple control scheme by means of the pressure monitor W 1 only as a function of the two pressure levels P _{3 and P 1 of} the low-pressure part. The play between gas supply and gas discharge caused by the temperature change has the further advantage that the gas can be passed through filters and thus cleaned and dehumidified independently of switching operations. This achieves a forced purging of the insulators arranged in the depressed area, which is of great advantage for the service life of the system. The process of the automatic gas circuit independent of switching operations can be extended by placing the pressure stage normal pressure P ₂ ) responsible for shutting down the compressor below the response pressure (lower operating pressure P ₁ ) of the reducing _{valve V 1} . However, a time relay is then required to shut down the compressor. However, this measure leads to an extended forced purging of the stressed insulation parts in the low-pressure part.

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Claims (5)

- 7 - 532/69 Claims Pressurized gas switch or pressurized gas-insulated switchgear with a high-pressure and a low-pressure part and a closed gas circuit, in which the high-pressure part is connected to the low-pressure part via at least one switching section provided with a blow valve and / or via a safety valve that responds at a maximum permissible pressure in the high-pressure part and the Gas return from the low-pressure part to the high-pressure part takes place by means of one or more compressors, characterized in that there is a buffer tank (P) in the gas circuit with a pressure higher than that of the high-pressure part (HD), to which both the high-pressure part and the low-pressure part (LP) are connected via reducing valves ( V ₁ , Vp) are connected, and that the compressor (K) connected to the low-pressure part and controlled solely by the pressure level in the low-pressure part has its output connected to the buffer tank. 2. Pressurized gas switch or pressurized gas-insulated switchgear according to claim 1, characterized in that the low-pressure part and the buffer tank are each provided with an outside safety valve (V ₅ , Vg) and that an additional gas supply (P) is connected to the buffer tank via a reducing valve (V.) is set to a nominal pressure (P «) assigned to the buffer tank, 3. Compressed gas switch or compressed gas-insulated switchgear according to claim 1 or 2, characterized in that the connection between the low-pressure part and the compressor can be blocked by .ein solenoid valve (Vm) which, when the minimum pressure is _{below the lower operating pressure (P 1} ) ( ^ans P ^ricnt 4. Compressed gas switch or compressed gas-insulated switchgear according to one of the preceding claims, characterized in that that for releasing the at the upper operating pressure (P,) - Ö - 00 98 A 2/0 57 9 PnI 4 f I (IHiB MOO / EAt 552/69 running compressor on when the lower operating pressure is reached starting time relay is provided » 5. Compressed gas-insulated switchgear according to one of the preceding claims, characterized in that on a buffer container several pressure gas switches are connected in parallel. . . 0098A2 / 0579 ! ' [LH I IMI ₁ (I ', IWiVI Λ) Blank page