JPS60200178A - Earth resistance meter - Google Patents

Abstract

PURPOSE:To separately measure the earthing resistance of an individual steel tower without generating the error based on the exciting current of a transformer, by using a square wave AC power source as an apply power source and eliminating the transformer not positive to a pulse current from a circuit. CONSTITUTION:The earthing resistor RA of a resistor R1 and an earthing electrode A to be measured and the earthing resistor RB of a first auxiliary electrode B are connected to a square wave power source 4' in series. The output voltage of the resistor R1 is applied to an amplifier 5 and one terminal of the rheostat 6 in the secondary outlet side thereof is connected to an earthing electrode A to be measured. In this state, formula I is formed. Earthing resistance RA can be indirectly calculated from the formula by R2. By this mechanism, the first auxiliary electrode B and a second auxiliary electrode C can be brought to a capacitive electrode sufficient to be merely layed to the surface of the ground. Further, the earthing resistance of a individual steel tower can be measured separately.

Description

[Detailed Description of the Invention] Conventional earth resistance meters can be roughly classified as shown in Figure 2.
From the sine wave AC power supply (hereinafter simply referred to as AC power supply ■) ■ to the ground electrode to be measured ■ through the primary winding of the transformer ■? [Flow 11■ is applied and the output resistor ■ is connected to its secondary terminal, and the voltage applied thereto and the grounding resistance RA■ of the grounding electrode to be measured ■
As shown in Figure 3, a single step voltage is applied to the ground electrode to be measured, and the Earth resistance RA
There is a single pulse application method in which a desired value is calculated from the voltage appearing at both ends of (2).

However, in the former case, since a transformer is interposed in the circuit, a) an error occurs due to the Ilh magnetic current, and b) the excitation characteristics of the transformer are nonlinear, so a pulse power source cannot be used as the applied power source, and a pulse power source is used. In the latter case, the voltage measurement type earth resistance meter shown in FIG. 3 does not provide various advantages in terms of measurement, and C) measurement becomes complicated because the power source is a single pulse.

d) Since this method directly measures the voltage appearing in the grounding resistance of the grounding electrode to be measured using a single pulse, a high-voltage power supply is required to energize the meter, which requires a large measuring instrument, heavy burden, and It becomes expensive.

e) If the grounding resistance Ra■ of the first auxiliary pole ■ is excessive,
Obtaining the desired single step current is difficult and introduces errors.

There is a flash of light.

The present invention uses a square wave alternating current power source as an applied power source, and eliminates a transformer that is not active for such pulsed currents from the circuit, thereby solving the above-mentioned conventional drawbacks at once.

The present invention will be explained in detail below with reference to the drawings. In Fig. 1, the grounding resistance R5 of the first auxiliary pole is connected in series with the resistor R and the grounding resistance of the grounding electrode to be measured. Connect to the square wave AC power supply φ, apply the output voltage of the resistor R to the multiplier ■, connect one end of the rheostatic resistor ■ on the secondary outlet side to the ground electrode to be measured, and connect the rheostatic resistor ■ a sliding intermediate terminal,
Connect the potentiometer ■■ between the grounding electrode to be measured ■ and the second auxiliary pole Ω located at the midpoint of the first auxiliary pole ■, and connect the rheostatic resistor ■
Adjust and draw a dot diagram where the indicated value of the potentiometer ■■ becomes zero. In such a case, from the same bone, I + RA = I x R2...1),',
RA = R2・I2/TI=R2・+・・・・・・1
') However, R2: This is the resistance value between the grounding terminal of the rheostatic resistor (2) and the slide intermediate terminal, and the grounding resistance RA can be indirectly set by R2. Here, the square wave AC pulse rIJ is toooμ
Must be S or higher.

First of all, since the present invention uses the above-mentioned 11 transformer in place of the transformer in the conventional zero-level method (FIG. 2), a) there is no error based on the excitation current of the transformer;

b) A pulsed power source can be used as the applied power source.

Furthermore, since a pulse power source is used, b-1) the first auxiliary pole (2) and the second auxiliary pole (O) can be made into capacitive electrodes that can be simply laid down on the ground surface.

b-2) With conventional measuring instruments that simply use an AC power supply, for example, in cases where each ground resistance is integrated with a ground wire, such as in a power transmission tower, it is possible to measure the ground resistance of each tower individually. Although it was impossible to measure it, this is possible because the present invention uses a pulsed power source.

Furthermore, since the present invention uses a square wave alternating current instead of a single pulse, C) a measurement method based on the zero position method can be adopted, similar to the conventional method using an alternating current power source, and the measuring instrument can be simplified.

d) Compared to the single pulse method, the power supply voltage is lower, and the method is smaller, lighter, and cheaper.

etc. characteristics occur.

Below, these features of the present invention will be explained in detail individually. Regarding a), in Fig. 2, if the transformer secondary current ■ is I, then 1
The next-side current I,
I. : Excitation current I' of the transformer, : Compensation current n of the primary side for the secondary current I2 of the transformer: Number of turns on the secondary side/number of turns on the primary side. Also in this figure, as explained in Figure 1 above. Same 1)
While the formula holds true, 2) Substitute the formula and get R4=R212/
I+ =R2・mouth・(1+1゜/I,) ・・・・・・1″
) On the other hand, in Fig. 2, if the power supply voltage is e, then e =
61+1 + (RA+ R11) --3) I8. +
(RA+Ra)-f(el) -...--3') e,: Primary side voltage of transformer f(eI): (=I l>-c, positive function of el 3)
Since e is constant in the formula, this is (R4 + R8)
If is large, it means that el is small. e at the place
The relationship of l0tI'1lIl to l is that, since the excitation characteristic I0 of the transformer is nonlinear as shown in Figure 4, in the region where e is extremely small, the ratio of 10H' becomes extremely small. It is easy to predict.

Therefore, if the ground resistance of the first auxiliary pole ■ is also extremely large, eI will be small, and the ratio of Io/I'+ will be extremely large accordingly, so if this is substituted for 1''), & will be large. Become.

In other words, according to such a conventional measuring device, the ground resistance RA, which should be constant, is forced to be largely influenced by the value of the ground resistance R@■ of the first auxiliary pole 0.

Since L' is used, in the 1'') equation, (■.Okiyo (Kurii Town I0)) is used, and RA is constant regardless of the horse's position.

Regarding b), if the power source to be applied in Fig. 2 is replaced with an AC power source ■ and a square wave pulse power source, the impedance seen from the primary side of the transformer ■' becomes extremely quotient at the wave head of the square wave. Therefore, for the reasons mentioned above, the current 1. is extremely small, so it is difficult to obtain a constant value for the ground resistance core in equation 1'' over the entire square wave region.On the other hand, in this application, a multiplier is used instead of a transformer as shown in Figure 1. Because of this, problems like this do not occur.

Regarding b-1), in the method of applying a single pulse voltage and measuring the voltage V■ as shown in Figure 3, if the grounding resistance of the 11 auxiliary pole ■ is connected to the net-like capacitive ground in the figure, this becomes As shown in Fig. 5, the current I and ■ are as shown in the following equation.

However, P: Operator E: Pulse voltage peak value In this method when applying a single pulse, the voltage V is measured assuming that the current 11■ is constant, as described in the explanation section for d) below. ■ To 1 = ■ ・・・・・・5) RA can be indirectly calculated as・・・・・・
...6).

By the way, in this method, since the applied voltage is a single step voltage, it is possible to select R sufficiently large with respect to 17Pc, l at the wave front, and equation 6) holds, and equation 4) becomes This holds true, and formula 5) holds true.

In other words, this method obtains the correct value at the wave front of a single pulse wave.

The above description has been made regarding FIG. 3, which is the method when applying a single pulse, but the same applies to the mi diagram, which is the zero position method.

However, in the conventional method of using a simple AC power supply, 1
/ PCdj' becomes extremely large, so that equation 6) does not hold, and therefore, equation 5) also does not hold.

Regarding b-2), when using a pulse power source as the power source as mentioned above,
It has been stated that the correct value of ground resistance can be obtained at the head of the pulse wave.

When a large number of tower leg connections (RA, R2, 瓜'...) such as a transmission line tower are connected in parallel through a ground wire as shown in Figure 716, the ground resistance is generally It is usually measured as a composite value of However, in the present application, etc., where pulse voltage is applied and measured, for example, when measuring & in the figure, if the measurement is terminated at the head of the pulse wave, which is the time when the pulse voltage wave travels back and forth between the turtle and R'A. This means that the true value of the RA length can be obtained, and this conforms to the illegal content that the correct value can be obtained at the wave head when applying the pulse described above.

Regarding C), since this application uses square wave alternating current as the power source,
The zero point method can be applied in the same way as when using a normal AC power supply, and the measuring instrument can be simplified.

Note that when using the single pulse method, it may be necessary to repeat measurements in order to improve accuracy, but in such cases, space charges may be generated in the ground, which may even lead to measurement errors. For this reason, it is also necessary to use alternating current as the power source.

d) Regarding In the single pulse method, the current I flowing in FIG.

Assuming that is constant, 1. It is said to measure RA=V and calculate the value of RA indirectly, but 1
1, in this cow diagram, as mentioned above, the current I
In order to make t apparently constant regardless of (R4+RB), R must be set to an extremely large value, as shown in R)(RA+R8). On the other hand, if R is increased, ■ becomes smaller. Measured value (1, R
Since A=V) also becomes smaller, in order to bring it within the measurement range of the meter, the voltage E in equation 7) must be increased, and the measuring instrument inevitably becomes larger, heavier, and more expensive. .

The present invention does not have such drawbacks because it uses a zero-level method using square wave alternating current.

As mentioned above, the present application is capable of making a ground resistance meter using the zero method by converting the transformer into an intensifier and changing the AC power source to a square wave AC. It has the feature of eliminating all the drawbacks of the one-pulse application method at once and promoting the advantages.

That is, 1) There is no gender-based error when energizing the transformer 2)
A capacitive mesh ground plate can be used as the first auxiliary pole and the second auxiliary pole. This is an alternative to the conventional method of excavating the ground to make auxiliary poles, and is convenient for application to asphalt-paved utility poles in urban areas.

3) The auxiliary ground resistance may be extremely high in gravel layers or rocky areas, but even in such cases, errors will not occur due to this. 4) This application uses the pulse method, but at the same time the zero position method is used. As with the zero-position method, the measuring equipment is small, simple, lightweight, and inexpensive.

[Brief explanation of the drawings] Figure 1 shows the earthing resistance meter of the present invention, Figure 2 shows the earthing resistance meter based on the conventional zero method, Figure 3 shows the earthing resistance meter based on the single pulse application method, and Figure 4 shows the earthing resistance meter based on the single pulse application method. The figure shows the excitation characteristics and load characteristics of the transformer, and FIG. 5 shows the case where capacitive grounding is used as an auxiliary pole in the single pulse application method. FIG. 6 is a diagram showing a case where a large number of ground electrodes are connected. ■: Low resistance: Grounding electrode to be measured ■: Grounding resistance R4 of the grounding electrode to be measured ■: 11 auxiliary pole ■; Grounding resistance RB of the first auxiliary electrode ■: Sine wave AC power supply ■: Square wave AC power supply φ: Single -Step voltage power supply ■: Increased 11J equipment: Transformer ■: Rheostatic resistor ■: Potentiometer ■: Primary current 1° ■: Secondary current I2 Ω: Second auxiliary pole [phase]: Second auxiliary pole Earthing resistance Rc Hllll"'l"h:+'I'+';1m %No change)+1 figure 1-September 4th Muyama July 6th, 1980 Commissioner of the Japan Patent Office 1. Indication of the case Patent Application No. 056698 1988 3
, Person making the amendment π Relationship with the matter Patent applicant 4, Statement of supplementary order f1 June 26, 1980 (shipment date) 5, Subject of amendment ``Application 1 and ``Drawings'' 6. Contents of amendment Amendment Application form (full text revised by Liu)

Claims (1)

[Claims] A ground resistance meter using the zero-level method uses a multiplier instead of a transformer in the circuit, and a square wave AC power source instead of a sine wave AC power source.