CN205880098U - Be used for low tension cable to break contact detection device - Google Patents

Abstract

The utility model discloses a low-voltage cable broken contact detection device, which includes a power factor meter and a self-defined impedance. The power factor meter is installed at the head end of the suspicious cable to detect the power factor phase angle of the suspicious cable; the self-defined The impedance is installed at the end of the suspicious cable; the self-defined impedance is composed of an adjustable resistor and an adjustable reactor in series; the self-defined impedance is set such that the impedance angle is constant and the impedance value can be adjusted and changed. The utility model has a simple structure. By installing a power factor meter at the head end of the suspicious cable and installing a self-defined impedance at the end of the cable, it is verified whether the measured power factor phase angle is consistent with the changing self-set impedance value to determine whether the cable has occurred. Broken contacts steal electricity.

Description

A device for detecting broken contacts of low-voltage cables

technical field

The utility model belongs to the technical field of electric power marketing equipment in electric power systems, in particular to a low-voltage cable broken contact detection device.

Background technique

In actual work, the 380V low-voltage cables that go out from the 10kV transformer are often laid underground or buried in walls. Especially when it comes to user assets, it is not easy to start the project to dig out the cables to determine whether to crack and steal electricity. The utility model is based on the characteristic that the impedance value of the low-voltage cable is almost negligible. A set of self-setting impedance value devices are installed at the outlet end of the low-voltage cable, and the power factor scale installed at the head end of the cable measures the voltage and current. Whether the power factor phase angle difference is consistent with the set impedance value is used to judge whether the low-voltage cable is broken to steal electricity. If not, it is considered that the cable is broken.

Contents of the invention

The technical problem to be solved by the utility model is to provide a detection device for detecting whether the low-voltage cable is broken.

The utility model solves the above-mentioned technical problems through the following technical solutions,

A device for low-voltage cable broken contact detection, including a power factor meter and custom impedance, characterized in that,

The power factor meter is installed at the head end of the suspicious cable to detect the power factor phase angle of the suspicious cable;

The self-defined impedance is installed at the end of the suspicious cable; the self-defined impedance is composed of an adjustable resistor and an adjustable reactor in series; the self-defined impedance is set such that the impedance angle is constant and the impedance value can be adjusted and changed.

As an optimization, the adjustable resistor is an HDK series adjustable resistor;

As an optimization, the adjustable reactor is a TKS series adjustable reactor.

The utility model has a simple structure. By installing a power factor meter at the head end of the suspicious cable and installing a self-defined impedance at the end of the cable, it is verified whether the measured power factor phase angle is consistent with the changing self-set impedance value to determine whether the cable has occurred. Broken contacts steal electricity.

Description of drawings

Fig. 1 is the utility model embodiment circuit diagram;

FIG. 2 is a structural diagram of a self-defined impedance circuit according to an embodiment of the present invention.

detailed description

Below in conjunction with accompanying drawing and embodiment, further set forth the content of the utility model in detail.

As shown in Figure 1, a device for detecting broken contacts in low-voltage cables includes a power factor meter and a custom impedance, and the power factor meter is installed at the head end of the suspicious cable to detect the phase angle of the power factor of the suspicious cable;

The self-defining impedance is installed at the end of the suspicious cable; the self-defining impedance is formed by an adjustable resistor and an adjustable reactor in series; the self-defining impedance is set so that the impedance angle is constant and the impedance value can be adjusted and changed; the The adjustable resistor is HDK series adjustable resistor; the adjustable reactor is TKS series adjustable reactor.

The working principle of the utility model is to install a power factor meter at the first end of the suspicious cable and install a custom impedance at the end of the suspicious cable to verify whether the measured power factor phase angle φ is consistent with the _self -defined impedance value phase angle φ. When the self-defined impedance changes continuously, the measured power factor phase angle φ will also change, for example, it is inconsistent with the impedance angle of the self-defined impedance; and if there is no cable break-contact stealing, the self-defined When the defined impedance changes continuously, the measured power factor phase angle φ remains unchanged, which is the same as the impedance angle of the custom impedance.

The specific working principle of the utility model is as follows: when a suspicious cable breaks a contact to steal electricity, the impedance value of the low _- voltage load resistance of _the broken contact is R+jX; The phase angle of the impedance value is φ _from , and the relationship between the phase angle of the impedance value φ _from and the impedance value is The resistance R and reactance X of _{the custom} impedance value can be adjusted proportionally to maintain the value, so as to ensure that _the values of _the resistance R and reactance X are changing, but the phase angle of _the impedance value is φ, _which does not change, for example, R =X remains unchanged, although _the values _of R and X are changing, but _the power factor _COSφ =0.5 remains unchanged.

If the suspicious cable is not disconnected, the power factor phase angle φ measured after the cable end is connected with the _custom impedance Rzi+jX should _be consistent with the _custom impedance angle phi.

If the suspicious cable is broken, there is a broken contact load impedance value of R+jX, and the _custom impedance R+jX connected to _the end of the cable forms a parallel circuit with the broken contact impedance. The equivalent impedance value of the parallel circuit is R _And + jX _and , the measured power factor angle φ is the power factor angle of the parallel equivalent circuit is φ _and . φ _and cannot _be consistent with φ. At the same time, the resistance R and reactance X _of the _custom impedance value are adjusted proportionally. When _the resistance R and reactance X are _in the same order of magnitude as R+jX, the measured φ _{and The} phase angle inconsistency with φ will be most apparent.

As shown in Figure 2, the custom impedance R _{from A} + jX _{from A} , R _{from B} + jX _{from B} , R _{from C} + jX _{from C} are the three-phase circuit A, B, C three-phase custom resistance and reactance Equivalent value, if the broken contact is only connected to one of the three phases A, B, and C, the power factor angle φ of this phase is inconsistent with the impedance value phase angle φ of the _custom impedance.

By installing a power factor meter at the first end of the suspicious cable, and installing a custom impedance at the end of the cable, the custom impedance is set to a constant impedance angle, and multiple sets of values that continuously change the impedance value from small to large. If there is no broken point, then The measured power factor phase angle of each phase is consistent with the self-set impedance value, otherwise it will be inconsistent.

Claims (3)

1. break for low-voltage cable and connect a point detection device, including power-factor meter and self-defined impedance, it is characterised in that

Described power-factor meter is arranged on suspected cables head end, the power factor phase angle of detection suspected cables；

Described self-defined impedance is arranged on suspected cables end；Described self-defined impedance is by trimmable resistance and adjustable reactor It is in series；Described self-defined impedance setting is that impedance angle is constant, change that resistance value is adjustable.

2. break for low-voltage cable as claimed in claim 1 and connect point detection device, it is characterised in that described trimmable resistance is HDK series adjustable resistance.

3. break for low-voltage cable as claimed in claim 1 and connect point detection device, it is characterised in that described adjustable reactor is TKS series REgulatable reactor.