JPS60183565A - Flicker type direct current grounding point searcher - Google Patents

Abstract

PURPOSE:To search for a grounding point securely, accurately, and easily without stopping a circuit regardless of the electrostatic ground capacity of the circuit of a detector by connecting a feedback part for an AC waveform current to the circuit. CONSTITUTION:The AC feedback part 5e which feeds the AC waveform currents in a circuit 5A back to the side of a detection terminal 5a is connected in the circuit 5A between a differential amplification part 5b and the detection terminal 5a. Then, when a grounding accident occurs, a DC grounded relay 3 operates to display a warning on a piping board. The switch 4A of a flicker relay 4 is turned on the confirmation of the warning and then a relay contact 4a is made and broken at a period set by a timer 6 to convert the grounding accident current into a rectangular pulsating current. This pulsating current flows only to the grounding point through a DC power circuit 2, so a detector 5 is used to trace it, thereby judging the grounding point.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention applies to direct current, which is often used as a power source for operating and controlling large-scale production equipment in various industrial fields such as automatic control equipment of power plants and substations, steel, petrochemicals, etc. When a grounding fault (grounding accident) occurs in the power supply circuit, it detects the grounding point and notifies the outside by visual means (lighting of a lamp or light emitting diode or indication from a meter) or audible means (buzzer). In detail, there is a DC grounding relay for ground fault detection installed in a DC power supply circuit to which I number of load circuits are connected in parallel, and a DC grounding relay connected in series to the grounding side terminal of this DC grounding relay so that the relay is grounded. A seven-point relay that converts the grounding fault current into a rectangular wave pulsating flow by opening and closing relay contacts when a fault current is detected, and clamps the grounding fault current converted to the pulsating current for each front P load circuit. The present invention relates to a DC grounding point searcher which is constructed by inserting a detector of the formula to detect the detected signal, amplify it, and output it to the notification section.

As mentioned above, if a grounding fault occurs at one point in the DC circuit network, which is spread over a wide range from the indoor protective relay to the outdoor device control system, the grounding fault will be followed by a grounding fault at the other pole. If the grounding 1 accident occurs one after another, it may develop into a short-circuit failure between both poles, causing wiring pus and disconnection (MC).
T3), etc., could cause a part of the control system or equipment to become inoperable, which would have an extremely serious negative impact on power generation/substation board performance and production functions. It is necessary to accurately and quickly search for the grounding point in the early stages of an accident, to promptly investigate the cause, eliminate the cause of the failure, and recover.

Generally, as shown in Figure 1, a direct current grounding appliance (64D in JLS standard) for ground fault detection is installed in the free-current power supply circuit (2).
31', a grounding accident may occur and the DC power supply (
2A) to the point where the fault occurred).
10) flows through the relay of relay (3) as shown by the arrow, and the operation of this relay indicates the occurrence of a grounding fault.
Is this method only for whether or not there is a grounding accident? It only detects the grounding point, but cannot search for the grounding point, and cannot meet the above-mentioned requirements.

The following search means are conventionally known as means that can meet the above-mentioned requirements.

(b) As shown in Figure 1 above, when only the DC grounding relay for ground fault detection is used, and this detects the ground fault sound and displays an alarm, switch 1 (1) to disconnect each of the load circuits mentioned above (7
a, wa b...)? DC grounding for ground fault detection after sequentially stopping through # Whether the electrical appliances are restored? The only way to find the grounding point by checking is to use a stop search method.

(b) All DC current transformers are installed between each load circuit connection point of the power supply DC circuit, and by automatic input switching via a non-contact switch, it is possible to detect approximately which region of the power supply DC circuit the grounding point is located in. Then, as in (a) 2 above, the circuit is stopped and searched for where the single ground point is located in each load circuit.

(c) When the DC earthing relay for ground fault detection detects u1, a means for passing a low frequency alternating current of about 10 to 30H2 through the circuit and detecting this.

However, the means for stopping the circuit as in (a) and (b) above do not require thermal control or
The situation is uncertain, and several shutdowns are required until the grounding point that requires restoration of the automatic control equipment of power generation and substations and production equipment to their intended functions is identified, and in particular, it is necessary to shut down the equipment several times. If the method is not equipped with a separate means, it requires the trouble of wiring at the terminal block, and there are disadvantages in that the downtime is very long.

In addition, as shown in f), the method of injecting low-frequency AC current into the circuit may not be detectable depending on the grounding and capacitance of the circuit, and is still not satisfactory in terms of condition applicability. The present invention was developed in view of the above circumstances, and regardless of the VP capacity of the circuit to the ground, or whenever the circuit needs to be stopped, the present invention is a grounding point. The purpose is to provide a DC grounding point searcher ft that is reliable, positive, and easy to search.

The 7-litre type DC grounded point purple detector according to the present invention devised to achieve the above object has the following configuration:
The present invention is characterized by a configuration in which an AC feedback section that returns an AC waveform current to the detection end side is connected in the circuit from the detection end of the detector to the notification section, thereby achieving the following. Did you get the effect? It was.

In other words, when a grounding occurs, the current flowing through one grounding point is used as is, but the magnitude of this grounding fault current is a weak current of about 2 to 3 mA even in a completely grounded state. If there is a DC load on top of this, it will be difficult to distinguish it from the load current. The present invention firstly focuses on this point, and
Flicker relay (4) as shown in Figure 2? By converting the ground DC current (10)'e into a rectangular wave pulsating current that is intermittent at a constant period, it is clearly distinguished from the load current when there is a negative DC IM.

Next, the rectangular wave pulsating current converted as described above is detected by the detector, amplified, and reported, but the pulsating current to be detected is very weak compared to the load current. The magnetic field generated by the current is also small, and a sensitive detector must be used accordingly, but this will reduce the high-frequency noise surrounding the wide-band transducer, inverter, etc. included in the detection circuit. The influence of the magnetic field generated by the AC waveform current, which is much larger than the ground fault current flowing from the 1i4A equipment, can be ignored, leading to false detection or failure to detect. The second feature of the present invention is to focus on this point, and by making efforts such as connecting a feedback section of the AC waveform current to the circuit of the detector, the current changes regularly in a relatively long period like the rectangular wave pulsating flow. Only the magnetic change that occurs is responded to, thereby reducing the voltage change in the output stage leading to the notification unit only to the direct current change due to the ground fault current,
Furthermore, as mentioned above, the period of the change is relatively long (change), and it is affected by the alternating current waveform current and high frequency noise.
It can be avoided.

As a result of the above actions, ■ there is no need to stop the circuit, and the power generation/substation functions and life-changing conditions caused by a grounding accident are eliminated. ! Avoid all negative effects on performance, [
Q) Road reliability P￥: Overall can be greatly improved.

(2) There is no need for personnel to confirm the return of the DC grounding relay, and multiple detectors can be used simultaneously, making the search for a grounding point more efficient and efficient.

(2) Since there is no loss of detection current due to the ground electrostatic charge of the circuit, there is no locational constraint that is overlooked in the conventional zero means described above, and the applicability of conditions can be sufficiently expanded.

■ Regardless of the existence of high-frequency AC waveform currents and broadband noise, only the weak grounding fault current can be extracted using a sensitive detector, making it possible to search for the desired grounding point with complete certainty and accuracy.

Such an effect? I ended up playing it.

Embodiments of the present invention will be described in detail below based on the drawings.

In Figure 3, (2) is the DC power supply of DCIIOV (
:This is a DC power supply circuit connected to 2~, and this circuit (2~
) has a DC load Q, a, , xb...in)
A plurality of load circuits (LA, 113...-1?
are connected in parallel, and these load amounts Wr
(LA, Lou1.$ are each equipped with a molded circuit breaker (MCB) at both poles. (3) is the DC power supply circuit (
2) A DC grounding relay for detecting ground faults is installed, and 7 Ritzker relays (4) are connected in series to its grounding side terminal. Is this flicker relay (4) a ground fault current? The operation (automatic or manual) of the reverse double switch (4A) based on the detected ψ alarm display causes the normally closed relay contact (4a)' to be connected to the variable tie (described later).
V-(1G) is opened and closed at the set cycle (05 to 1 second) to check the grounding fault current? It has the function of converting it into a rectangular wave pulsating flow and sending it to the ground point through the circuit (2), and the variable timer (b) has the function of converting it into a rectangular wave pulse flow and sending it to the ground point through the circuit (2).As shown in FIG. Two timers (TO, (r2)) are connected in parallel to a circuit connected to a circuit in which the AC 200V power supply voltage can be switched to 220v or 110v via an isolation transformer (Tr), and each timer contact (TI-
8), (r+-b), (T2-a), (■゛2
-b) It is configured by connecting 2 through 1/. (5) is a detector for detecting the grounding fault current r converted into the pulsating flow through the flicker relay (4) and detecting all the grounding points, and this detects the constant voltage 'rl+l< (Clamp type detection end (5a) where constant voltage is supplied from 5*
, a differential amplification section (5b), an integral@width section (5C) and a notification section (5d) having a single alarm and a level meter, and rFD information from the detection end (5a). (
In the circuit (5A) up to No. 5, the differential amplifier Ei'
il (5b) and the detection end (5a),
It is constructed by connecting the original waveform current in the circuit (5A) to the detection end (5→AC that returns to the feed, feedback part φθ), and this detection! i! (111 is a portable case in which the clamp terminal (5f) is exposed as shown in Fig. 5 (5th is the alarm part G5d such as a level meter (SA) and speakers (5d, s)) , sensitivity adjustment switching range (5h), battery checker (51),
and 'i>t W switch (5J).

Next, to briefly explain the grounding point ignition method using the flicker type I-flow grounding point searcher with the above configuration, when a grounding accident occurs, the DC grounding relay (3) is activated and the Display a warning.

I acknowledge this 9# report (based on flicker relay (4)
When the switch (4A)' is turned on and operated, the relay contact (
4 → is the cycle (0, 5 to 1) set by the timer (6)
It opens and closes in seconds) to convert the ground fault current into a rectangular wave pulsating current (flicker). Since this pulsating current flows only to the ground point throughout the circuit (2), if you follow its path using the detector (5), you will naturally find the ground point.

The internal circuits of the AC feedback section φe) and the detection section (5a) in the detector (5) are configured using an AC path circuit, a feedback coil, and a Hall element, and the specific configuration is well known. Therefore, its description will be omitted.

[Brief explanation of the drawing]

Figure 1 is a conceptual diagram showing general grounding detection procedures, Figure 2 is a conceptual diagram showing means for distinguishing between earth fault current and load current, Figure 3 is the overall block e:<], Figure 4 is variable The circuit diagram of the timer, FIG. 5, is an external view of the 1U unit. (IA, IB...1 埒...Load circuit, (2
)...... DC circuit is also the source circuit, (3)...... Ground fault detection rigidity i) is j' bar, earth motion electric device, (4)...
Flicker relay, (4a)...Relay contact,
(5)...Detector, (5a)...Detection end, (5d)...Notification section, (5G)...
AC return department. Figure 1 Figure 2 Izz

Claims (1)

[Claims] ■ A DC power supply circuit (2) in which a plurality of load circuits (IA, IB-...1) are connected in parallel; ) is connected in series with the grounding side terminal of this DC grounding relay (3), and when the relay (3) detects a grounding fault current, the relay contact (4a
) r A flicker relay (4) that converts the grounding fault current into a rectangular wave pulsating current by opening and closing, and a flicker relay (4) that converts the grounding fault current into a rectangular wave pulsating current, and a flicker relay (4) that converts the grounding fault current into a rectangular wave pulsating current to each of the load circuits (IA, 1B
It is a DC ground point searcher consisting of a detector (m) which detects and amplifies the detected signal by inserting a tarlamp type detector in each group and outputs it to the notification unit (cd). , from the detection end (5a) of the detector (5) to the notification section (
5) In the circuit (5A) up to the circuit (5A), there is an AC feedback section (SA) that returns the AC waveform current to the detection end (5→ side). Search device. ■ Relay contact (4a) of the Zulitzker relay (4)
7. The DC ground point probe according to claim 0, wherein the opening/closing speed is variable.