JPS6319323Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to an external power supply device for cathodic protection that performs cathodic protection on objects to be protected such as pipes buried in the ground. The purpose of this study is to reliably know the corrosion protection potential.

If the normal corrosion protection potential of an object to be protected such as a pipe in the ground or water is measured while the object is being electrolytically protected, the voltage drop due to the resistance in the ground or water will be included in the measured value. Therefore, it was not possible to directly know the true corrosion protection potential of the object to be protected.

For this reason, conventionally, when trying to find out the corrosion protection potential of a target object, the so-called off-potential method was used, in which the corrosion protection work on the target object was stopped, that is, the corrosion protection power supply was turned off, and the potential of the target object was measured. It was being measured.

However, this off-potential method has the disadvantage that the corrosion protection power source must be turned off each time the corrosion protection potential of the object to be protected is checked, making the work of checking the corrosion protection potential of the object to be protected complicated.

In addition, since the anti-corrosion power source must be turned off every time the corrosion protection potential of the object to be protected is to be determined, there is a problem in that the corrosion protection of the object to be protected cannot be constantly monitored.

Furthermore, when attempting to measure the corrosion protection potential of a target object that has been electrolytically protected by multiple external power supplies, all external power supplies installed on the target body must be turned off. Therefore, it is economically unfeasible to measure the corrosion protection potential of objects to be protected using this off-potential method in long facilities, and in fact, there have been no examples of measuring the corrosion protection potential of long facilities using the off-potential method. .

By the way, since the ideal power source for cathodic protection is a smoothed DC power source that does not fluctuate over time, conventional external power supplies have been equipped with a smoothing circuit to provide corrosion protection voltage with less ripple. , a corrosion protection current was supplied to the object to be protected, but it is known that some interruption of the corrosion protection current is allowed in actual cathodic protection.

The present invention was devised to eliminate the inconveniences and shortcomings of the conventional examples described above, and takes advantage of the fact that some interruption of the corrosion protection current is allowed in actual cathodic protection as described above. It is configured to detect the corrosion protection potential of the object to be protected at each point in time when the current is interrupted.

An embodiment of the present invention will be described below with reference to the drawings.

The external power supply device for cathodic protection according to the present invention connects a commercial single-phase AC power source f to an input terminal, connects one output terminal to a current-carrying electrode 4, and connects the other output terminal to a pipe buried in the ground, etc. a power rectifier circuit 1 connected to the object 5 to be protected from corrosion; a peak wave detection circuit 7 having one input terminal connected to the object 5 to be protected and the other input terminal connected to the reference electrode 6; and a DC voltmeter 8 inserted and connected between both output terminals of the wave detection circuit 7.

The power supply rectifier circuit 1 is for obtaining pulsating DC power from a commercial single-phase AC power supply f, and does not have a smoothing circuit.

In the embodiment shown in FIG. 1, the power supply rectifier circuit 1 is comprised of a transformer 2 and a half-wave rectifier 3, but a full-wave rectifier may also be used as the rectifier 3.

The peak wave detection circuit 7 basically uses a peak hold circuit consisting of a diode D and a capacitor C as shown in FIG. An amplifier 11 is provided to compensate for this, and resistors R1, R2 and a comparator 12 are provided to obtain more stable operation.

The object to be protected from corrosion 5 is connected to one input terminal of the peak wave detection circuit 7, and the reference electrode 6 is connected to the other input terminal. The highest corrosion protection potential of the body 5 is detected and output to the DC voltmeter 8.

Now, since the power rectifier circuit 1 is mainly composed of a rectifier 3 that does not have a smoothing circuit, the anticorrosion voltage obtained from the power rectifier circuit 1 has a pulsating waveform when the rectifier 3 is full-wave rectifier. Therefore, the anti-corrosion current Ia supplied to the object to be protected 5 by the anti-corrosion voltage in the form of a pulsating wave forms a pulsating wave as shown in FIG.

Therefore, the corrosion protection voltage Va is as shown in Fig. 4.
The potential becomes zero a number of times in one second depending on the frequency of the single-phase AC power source F, and when this anti-corrosion voltage Va becomes zero potential, the anti-corrosion current Ia to the object to be protected 5 also becomes zero.

As shown in FIG. 4, the corrosion protection potential V of the object to be protected 5 reaches its maximum value when the supplied corrosion protection current Ia is zero, and reaches its lowest potential when the corrosion protection current Ia reaches its maximum value.

Then, the corrosion protection potential V which became this highest potential
The value of 2 becomes the true corrosion protection potential of the object 5 to be protected.

In addition, in FIG. 4, V3 is the natural potential of the object 5 to be protected from corrosion.

That is, if the corrosion protection potential V of the object to be protected 5 is measured at the time when the anticorrosion current Ia to the object to be protected 5 becomes zero, this potential V2 is determined by the electrolyte medium 9 such as soil.
This is the true corrosion protection potential of the object 5 to be protected, which does not include the resistance voltage drop in .

By the way, as described above, the peak wave detection circuit 7 detects the highest potential V2 of the object to be protected 5, that is, the potential V2 when the corrosion protection current Ia to the object to be protected 5 becomes zero.
is measured and taken out, and this is displayed on the DC voltmeter 8, so that the corrosion protection potential of the object to be protected 5 at the time when the corrosion protection voltage Va becomes zero is displayed.

That is, the external power supply device for cathodic protection according to the present invention can accurately and easily know the true corrosion protection potential V2 of the object to be protected 5 without turning off the power supply voltage.

Furthermore, even if the object to be protected 5 is long and a single object to be protected 5 is provided with a plurality of external power supply devices for cathodic protection, each external power device can supply a single commercial single-phase AC power source. When using a corrosion-proof power source, the object to be corroded 5 can be connected without stopping each external power supply device.
The true anti-corrosion potential V2 can be known at any point at any time.

As is clear from the above explanation, the external power supply device for cathodic protection according to the present invention can determine the true corrosion protection potential of the object to be protected at any point and at any time without stopping the corrosion protection effect on the object to be protected. As a result, it is possible to effectively streamline the corrosion protection management of the object to be protected, and even if a large number of external power supplies for cathodic protection are provided for a single object, each external Under the condition that the power supply equipment uses the same commercial single-phase AC power supply as the corrosion protection power supply, it is possible to accurately know the true corrosion protection potential of the object to be protected at any time while all external power supplies are operating. Furthermore, since it is only necessary to provide a peak wave detection circuit instead of removing the smoothing circuit from the power supply rectifier circuit, the configuration is extremely simple and has many excellent effects.

[Brief explanation of drawings]

FIG. 1 is an electric circuit configuration diagram showing an embodiment of an external power supply device for cathodic protection according to the present invention. Second
The figure is an electric circuit diagram showing an example of the configuration of a peak hold circuit which is a main component of a peak wave detection circuit which is a component of the device of the present invention. FIG. 3 is a corrosion protection current waveform diagram showing an example of the corrosion protection current produced by the device of the present invention. FIG. 4 is a diagram of a corrosion protection potential waveform of an object to be protected against corrosion by the apparatus of the present invention. Explanation of symbols 1; Power rectifier circuit, 2; Transformer,
3; Rectifier, 4; Current-carrying electrode, 5; Corrosion-protected object,
6; reference electrode, 7; peak wave detection circuit, 8; DC voltmeter, f; commercial single-phase AC power supply, Ia; anti-corrosion current,
Va: Corrosion protection voltage.

Claims (1)

[Scope of utility model registration request] A power rectifier circuit with a single-phase AC power supply connected to the input terminal, one output terminal connected to a current-carrying electrode, and the other output terminal connected to the object to be protected from corrosion, and one input terminal connected to the object to be protected from corrosion. 1. An external power supply device for electrolytic protection, comprising: a peak wave detection circuit having the other input terminal connected to a reference electrode; and a DC voltmeter inserted and connected between both output terminals of the peak wave detection circuit.