CN2141901Y

CN2141901Y - DC line leakage current testing arrangement

Info

Publication number: CN2141901Y
Application number: CN 92241572
Authority: CN
Inventors: 郑凯
Original assignee: Individual
Current assignee: Individual
Priority date: 1992-11-20
Filing date: 1992-11-20
Publication date: 1993-09-08
Anticipated expiration: 2002-11-20

Abstract

The utility model relates to a DC line leakage current testing arrangement apparatus, which is composed of an outer shell, a DC leakage current detection transformer, a rectification circuit, a voltmeter, etc. The dc leakage current detection transformer is composed of an iron core, a primary side winding and a secondary side winding; the primary side winding is connected with an AC excitation power supply, and the secondary side winding is connected with the voltmeter by the rectification circuit; a DC line which is tested penetrates through the center of the iron core. The utility model can be used for various line devices including a DC control and testing system.

Description

DC line leakage current testing arrangement

The utility model relates to a kind of device that detects the DC line leakage current.

The device that detects the DC line electric leakage at present has only a grounding alarm relay, it can only demonstrate dc system grounding, and a straight-flow system has many DC loop usually, it can not determine a certain concrete faulty line and equipment, operate a switch to the loop one by one if will find concrete circuit and equipment, find concrete faulty line, and then progressively check concrete equipment, find fault.Check that like this trouble spot just wastes time and energy very much, low and some equipment of efficient is in operation and does not allow to have a power failure, and this just brings very big difficulty to fault handling.For the detection of DC equipment electric leakage, also lack simple, reliable, effective checkout equipment at present.

Based on above-mentioned the deficiencies in the prior art, the purpose of this utility model is the earth detector that the detection for the DC line leak current fault provides a utilization electromagnetic technique to finish, it can demonstrate concrete faulty line accurately and timely, and straight-flow system is not had any interference.

The major technique formation that realizes above-mentioned purpose is, this DC line earth detector comprises shell, detection of electrical leakage mutual inductor, rectification circuit, voltage table etc., the detection of electrical leakage mutual inductor is made of iron core, first side winding and secondary side winding, first side winding connects ac excitation power supply, the secondary side winding output terminal connects voltage table by rectification circuit, and detected DC line is passed iron core central authorities.

Its brief introduction of work principle is as follows: the AC power of first side winding induces stable alternating voltage by transformer iron core at secondary side, by demonstrate certain value after the rectification on voltage table.Dc wire passes transformer iron core, and under normal operating condition, cancel out each other in the magnetic field that positive and negative lead produces in iron core, and the secondary side output voltage is not had influence, and voltage table shows normal; When DC line broke down, because electric leakage, then the current imbalance that positive and negative lead flow through of dc wire produced an exciting current in iron core, and then the output voltage of mutual inductor secondary side changes, and voltage table promptly demonstrates this changing value.The maintainer just can know the faulty line of straight-flow system immediately, the circuit inspection of operating a switch one by one.During use, this device is fixedly mounted in each bar loop of straight-flow system.

Adopt the utility model to detect the electric leakage situation of straight-flow system, compare with prior art, it can demonstrate faulty line accurately and timely, needn't be to each bar loop of straight-flow system inspection of operating a switch, reduced the loss of unnecessary human and material resources, for the fault detect of DC line provides a kind of convenience, pick-up unit efficiently.And it is simple in structure, highly sensitive, convenient and practical, safe and reliable.

Below in conjunction with accompanying drawing the utility model is described in further detail.

Fig. 1. be outside drawing of the present utility model;

Fig. 2. be Fig. 1. side view;

Fig. 3. be electrical schematic diagram of the present utility model;

Fig. 4. be Fig. 3. the voltage oscillogram of middle primary side, secondary side.

As Fig. 1., 2. shown in, on shell, be furnished with voltage table 2., perforation 4. of test knob 3. dc wires and ac excitation power supply connection terminal 5.6. are installed in this device in each bar DC line when specifically using, dc wire passes dc wire hole 4.

Schematic diagram of the present utility model such as Fig. 3, ac excitation power supply U1 enters first side winding L1 through connection terminal 5,6, and induces a sinusoidal voltage U2 on secondary side L2, and U2 demonstrates certain value through rectification circuit D on voltage table 2.Pass dc wire positive and negative current in wire balance when normal operation of iron core, the secondary side output voltage is had no effect; When there was leakage current in dc wire, positive and negative current in wire balance was broken, and then the induced voltage in secondary side winding changes, and correspondingly, demonstrated a fault value on the voltage table, indicated this DC loop leak current fault to occur.

First and second side voltage waveform such as Fig. 4 in its course of work.Fig. 4 a is the waveform of U1, and Fig. 4 b is a U2 waveform just often; Fig. 4 c is the fault waveform of U2 when DC leakage current.Primary side adds a sinusoidal voltage U1, and waveform such as Fig. 4 a are unsaturated as iron core, induces sinusoidal voltage U2 at secondary side and makes the iron core generation saturated if add a direct current electric current, and then secondary side induced voltage U2 will descend, and saturated is serious more, and it is serious more that U2 descends.If make iron core slightly saturated the exciting curent that U1 produced, the waveform of the output voltage U 2 of secondary side demonstrates the waveform of Fig. 4 b on oscillograph.At this moment, if add a direct current electric current again, then core sataration increases the weight of, and U2 descends, and its waveform is as described in the 4c.

Therefore, can judge having or not of DC leakage current by the variation of output voltage U 2.Simultaneously, because the variation of output voltage U 2 and DC leakage current have certain relation therefore also can estimate the size of leakage current by the changing value of output voltage U 2 effective values.

For improving the sensitivity that this device detects leakage current, it is unsuitable excessive to exchange exciting curent, preferably milliampere level.And the number of turn of first side winding should be less than the number of turn of secondary side winding L2.

In actual motion, most times of DC line are in normal operating condition, for whether this device of check is normal in good time, this device also is provided with the test loop, promptly on transformer iron core, increase by a test winding L 3, the negative pole of one termination DC line mains side of test winding L 3, the other end connects the positive pole of DC line load side by test knob 3, resistance R, as shown in Figure 3.Press knob 3 and be equivalent to make the leakage current that a people is at this device, then voltage table demonstrates fault value, shows that instrument is normal.Otherwise illustrate that this device has fault, should in time overhaul.

If provide the interchange exciting curent with existing electro coupled oscillator circuit, the utility model can also make portable, and circuit is still as Fig. 3, but only need be made the split structure with transformer iron core, and the scene is placed in one dc wire can detect.

Claims

1, a kind of DC line leak current detection device is characterized in that: this device is made up of shell, direct current detection of electrical leakage mutual inductor, rectification circuit, voltage table; The detection of electrical leakage mutual inductor is made of iron core, first side winding, secondary side winding; First side winding connects ac excitation power supply, and the secondary side winding output terminal connects voltage table by rectification circuit; Detected DC line is passed iron core central authorities.

2, device as claimed in claim 1, but it is characterized in that the split structure that transformer iron core is made up of two iron cores.

3, device as claimed in claim 1 is characterized in that being wound with the battery of tests winding on the iron core of this device, and the negative pole of a termination DC line mains side of test winding, the other end connect the positive pole of DC line load side by test knob, resistance; The test knob is contained on the shell.

4, as claim 1,3 described devices, it is characterized in that being furnished with on the shell voltage table, the test knob, the excitation power supply connection terminal is provided with the dc wire perforation below shell.

5, device according to claim 1 is characterized in that exchanging exciting curent and is a milliampere level, and the number of turn of first side winding is less than the number of turn of secondary side winding.