DD234541A1 - METHOD FOR THE MONITORING OF INTERFERENCE LIGHTS IN SWITCHES AND PRODUCTS - Google Patents

Abstract

The method is used for the monitoring of faulty arc in open or encapsulated electrical equipment as well as in factory or locally manufactured products. Stoerlichtboegen should be detected within 5 ms with security, in order to be able to perform a fast shutdown and thus to prevent harmful effects by pressure and radiation. It is proposed that when exceeding a minimum value of the current increase (di dt) and the absolute value of the current over a minimum subtransient short-circuit alternating current (IK) corresponding value over a period of 2.5 ms and the simultaneous response of an optical light detection element, a pulse for Triggering the arc supplying switching devices is given. figure

Description

-2- 730 41

embodiment

The invention will be explained in more detail below using an exemplary embodiment. The drawing shows a switchgear in which a subvoltage busbar 1 is fed via a transformer 2 from a high voltage busbar 3.

When an arc occurs, the light pulses from the sensors of an electric arc monitor 9, which are arranged at störüchtbogengefährdeten points of the units, fields, cabinets, or compartments of the monitored system, detected and transmitted to the evaluation unit 10. The processed by the evaluation unit 10 signal is transmitted to the AND gate 11 of the synchronous logic 4.

From the current transformers 12 of the supply of the switchgear the current is detected on both the upper and lower side three-phase and guided to the evaluation units 13 for monitoring the absolute value of the current and the evaluation units 14 for monitoring the current increase. When a subtransient AC short-circuit current occurs (Ik ") or when a minimum adjustable value of the current rise (-) is exceeded, these deliver a signal which is transmitted via the AND gate.

dt

Links 15 on time evaluation units 16 is performed. If there is a signal of more than 2.5 ms at the time evaluation units 16, a pulse is applied to the AND elements 17, the pulses occurring in parallel from the arc monitor 9 and the circuit breaker-on display of the auxiliary switches 18 of the circuit breakers. and 8 processed.

In the case of an existing pulse train, a pulse is applied via the evaluation unit 20 and the AND gate 11 to the synchronous logic 4 which, given the control voltages (DC or AC voltage) monitored by the evaluation unit 19, simultaneously applies a triggering pulse of> 20 ms pulse width to the thyristors 5 , the short-circuiter 6 and the higher-level circuit breakers 7 and 8 triggers. The short-circuit current, which feeds the arc, commutes to the thyristors 5, whereby the arc is extinguished instantly, then commutated to the short-circuiter 6 and is turned off by the parent circuit breaker 7 and 8 respectively.

For non-transformer supplied low voltage systems, the monitoring circuit is required only once.

The arc monitor is used to locate the fault location and there is a decentralized fault current display on site. A central display is additionally possible.

Claims (2)

-ι- 730 41 claims A method for monitoring arc in open or encapsulated electrical switchgear and products using optical arc detecting members characterized in that the current increase (- ^) and the absolute value of the current are monitored in three phases and at a minimum value of the d - t -. Current increase (--- ·) as well as the absolute value of the current over the minimum subtransient -dt Short-circuit alternating current (Ik ") corresponding value over a period of 2.5 ms and the simultaneous response of an optical light sensing elementein pulse is given to draw the arc feeding switching device 2. The method according to claim 1, characterized in that the Ausloseimpuls takes place only when the state of the feeding the arc feeding feeders and in the presence of DC and / or AC control voltages For this 1 page drawing Field of application of the invention The invention relates to a method for monitoring Storhchtbogen in open or encapsulated electrical equipment and in fabnkfertig or locally made products Characteristic of the known technical solutions Despite sophisticated design measures and careful production, it is not possible to completely prevent the occurrence of arc flashover in electrical equipment. Despite the use of insulation coordination, arc flashover or switching overvoltages in the network, faulty switching operations or device faults can trigger a fault arc due to the resulting pressure wave and the radiation effect The damage level and the extent of the hazard depend essentially on the duration of the arc, depending on the Auslosezelten the upstream switchgear up to several seconds It is therefore already known various measures to shorten the exposure time of the Storhchtbogens By devices which detect the occurrence of a Storhchtbogens with light, pressure or temperature-sensitive sensors is acted on the upstream switching device which causes the shutdown of the protected unit The solutions, however, have several disadvantages Arrangements that are used in particular in medium-voltage switchgear and pressure relief and via these coupled Kontaktvornchtungen the draw of the upstream switch takes place, need a stimulation time to detect a Storhcntbogens of at least 10 ms Such druckempfind Liehe systems are also only in encapsulated plants usable Arrangements with thermally induced draw also have long stimulus times Although optical arc detectors have a short excitation time, but not in all cases storquellensicher, so that switching errors due to switching arc or extraneous light can not be completely ruled out. To distinguish between Storhchtbogen and Schalthchtbogen, it is known that This, in turn, increases the exposure time of a Storhcntbogens For consideration of extraneous light incident with the proposal according to etz Bd 104 (1983) 18, page 475-478 a solution is known, but this circuit is not completely storungssicher, since not It is certainly possible to differentiate between a control loop and a crosstalk arc. Various factors to be determined empirically must be taken into account when setting the threshold of the arc switch, which makes the use of the system operator possible A total of more than 40 ms is required, which is still too high Object of the invention The aim of the invention is to safely select a faulty arc within 5 ms of sources of interference, Fremd B ambient light incidence and switching arc, in order then to be able to perform a rapid shutdown and thus prevent harmful effects by pressure and radiation Explanation of the essence of the invention The technical problem that is solved by the invention The invention has the object of specifying a method with which a fault arc can be detected within 5 ms as such and the influence of switching bow arc and extraneous light incident can be eliminated Features of the invention Erfirdungsgemaß the object is achieved by the fact that in addition to optical L'artebogenerfassung the current increase and the absolute value of the current are monitored in three phases While exceeding a minimum value of the current increase (-) and the absolute value of the minimum subtransient short-circuit alternating current (l <') 0.0 corresponding value over a period of about 2.5 ms and the simultaneous response of an optical Lichtfassungsghedes an impulse takes place to draw the switching elements, z. B of the higher-level circuit breaker or a short-circuiter Furthermore, the on state of the associated feed switching device and the presence of required for the shutdown grid-independent DC and / or AC control voltage are monitored, so that a shutdown can only be done if the associated or the circuit breaker, the Supply arc (feeds) are switched on and the control voltages are applied Due to the simultaneous monitoring of the absolute current value, the current increase as well as the optical arc monitoring, arc log can be reliably recognized as such, since switching arc loops have decayed again within 2.5 ms and a response by Fremdhcht is prevented by the simultaneous current monitoring