CN203658510U - Voltage transformer secondary circuit grounding detector - Google Patents

Abstract

The utility model discloses a voltage transformer secondary circuit grounding detector, and uses a current measurement principle. A front panel is provided with an AC ampere meter indicating unit, an isolating switch control unit and a measuring hole, and is used to lead out a detection pen clip; a side panel is a lightning arrester insurance replacement kit, and is internally a detection circuit; when the side panel is used, two ends of a zero phase miniature bus grounding wire are released to introduce the detection pen clip; and an isolating switch opens and closes, so that current value changes before and after opening and closing can be observed, and the rapid determination objective is realized. The voltage transformer secondary circuit grounding detector can separately measure different branches, gradually investigate grounding failure points, and narrow the measurement range so as to quickly find the grounding wire; and the voltage transformer secondary circuit grounding detector is compact in appearance and convenient to be carried by hands, is visual and efficient, and is worthy of promotion and use.

Description

A voltage transformer secondary circuit grounding detector

technical field

The utility model relates to the technical field of electric power grounding detection equipment, in particular to a secondary circuit grounding detector of a voltage transformer.

Background technique

Potential transformers, like many electrical equipment, are not allowed to be short-circuited. Therefore, the secondary circuit must be grounded at one point in the control room through the zero-phase small busbar to prevent high voltage from going to the secondary side. However, if there are two or If there are many places, it will cause polarity and phase errors, resulting in short circuit and burning of the secondary coil of the voltage transformer.

In actual operation, due to reasons such as design, construction, secondary equipment aging, and insulation breakdown, two-point or multi-point grounding often occurs. In the process of finding the problem, it is necessary to check each screen and terminal box one by one. There are many working places and heavy workload, and it is often impossible to check the danger in time, which not only affects the operation of the protective instrument, but may also cause equipment damage and personal electric shock accidents.

Utility model content

The purpose of the utility model is to provide a voltage transformer secondary circuit grounding detector, which has a small appearance, is convenient to carry in the palm, is easy to use and operate, and can quickly realize the detection function.

In order to achieve the above purpose, the technical solution adopted by the utility model is: a voltage transformer secondary circuit grounding detector, including a detector body and an external measuring pen, and the detector body includes an AC ammeter, an isolating switch, a detection resistor , two measuring holes and an arrester fuse box, the detection resistor and the isolating switch form a parallel circuit, the parallel circuit and the AC ammeter form a series circuit, and the series circuit is connected in parallel with the arrester fuse box.

The external measuring pen is a clamp structure, and the lightning arrester is zinc oxide breakdown insurance.

When measuring, use a measuring pen clamp to connect the terminal connected to one point of the zero-phase small busbar grounding wire, and then untie the two ends of the zero-phase small busbar grounding wire.

Open and close the isolating switch, read the current representation value before and after opening and closing respectively, and compare the two current representation values; if it is basically unchanged, the line is normal, if there is a large change, there is multi-point grounding, so as to Determine whether there is a fault; if there is a fault grounding situation, the measuring instrument can be gradually introduced into the lower branch, and the above method can be used to judge whether the fault occurs in the measured branch, so as to finally find the grounding branch and remove the grounding point.

The utility model is only connected by a circuit composed of simple electronic components, without introducing other complex logic operation modules, that is, it realizes the quick search and judgment of the grounding problem point, has the characteristics of intuitionistic and high efficiency, and is worthy of popularization and use.

Description of drawings

Fig. 1 is a schematic view of the front appearance of the utility model.

Fig. 2 is the internal structure diagram of the back side of the utility model.

Fig. 3 is a schematic circuit diagram of the utility model.

Detailed ways

As shown in Figures 1 and 2, a voltage transformer secondary circuit grounding detector includes a detector body 1 and an external measuring pen 2, and the detector body 1 includes an AC ammeter 3, an isolating switch 4, a detection resistor 5, The two measuring holes 6 and the arrester fuse box 7, the detection resistor 5 and the isolating switch 4 form a parallel circuit, the parallel circuit and the AC ammeter 3 form a series circuit, and the series circuit is connected in parallel with the arrester fuse box 7.

The tip of the external measuring pen is a wire clip 8 structure, and the lightning arrester is a zinc oxide breakdown insurance 9 .

The detection principle circuit diagram is shown in Figure 3. The detection resistance R is a standard resistance of 10Ω, the ammeter PA is an AC pointer ammeter with a range of 0 to 200 mA, and the zinc oxide arrester F is a rated 380V breakdown insurance.

Before the measurement, it is necessary to insert the external measuring pen 2 of the tester into the measuring hole, and check whether the lightning arrester insurance 9 is in good contact. Open both ends of the zero-phase small busbar grounding wire.

First perform the closing operation of the isolating switch 4. At this time, the detection resistor 5 is not connected to the detection circuit. The ammeter is equivalent to measuring the current of the original grounding wire. Read the current value at this time, which can be recorded as I1; and then isolate The opening operation of switch 5 is to connect the detection resistor 5 into the detection circuit. The current is equivalent to the current after the original point grounding wire is connected in series with the detection resistor R. When reading the current value at this time, it can be recorded as I2; the two current representation values For comparison, if the current indication value is basically unchanged, it means that the line is normal, that is, there is only one point of grounding, and if the change is large, it means that there is a fault, that is, there are two or more points of grounding; The instrument gradually introduces the lower-level branch, and uses the above method to measure step by step to determine whether the fault occurs in the measured branch, so as to finally find the grounding branch and remove the grounding point.

After the ground fault point is removed, retest the primary ground point of the zero-phase small bus to ensure that all other fault ground points have been removed.

The utility model is only connected by a circuit composed of simple electronic components, without introducing other complex logic operation modules, that is, it realizes the quick search and judgment of the grounding problem point, has the characteristics of intuitionistic and high efficiency, and is worthy of popularization and use.

Claims (2)

1. A voltage transformer secondary circuit grounding detector, comprising a detector body and an external measuring pen, the detector body including an AC ammeter, a disconnector, a detection resistor, two measuring holes and a lightning arrester fuse box, the detection The resistor and the isolating switch form a parallel circuit, the parallel circuit and the AC ammeter form a series circuit, and the series circuit is connected in parallel with the lightning arrester fuse box. 2. A voltage transformer secondary circuit grounding detector according to claim 1, characterized in that: said external measuring pen is a clamp structure, and said lightning arrester is zinc oxide breakdown insurance.

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