RU1809841C - Set for cathodic corrosion protection of underground objects of extensive length - Google Patents

Abstract

Usage: cathodic protection against corrosion of long underground objects in alternating zones with a high density of stray currents. Summary of the invention: the installation comprises an alternating pulse generator 1, a linear wire 3, a comparison device 4, a device 6 and an earthing switch 7. The adjustable device 6 is made in the form of two transistors of opposite types of conductivity, the bases of which are connected to the output of the comparison device, the collectors to the ground and emitters to the line wire. The maintenance of the proposed device is greatly simplified, since there are no complex linear devices and the inclusion of all elements of the protection circuit is carried out within the station: in the office premises of the plant, on the input devices and in the cabinets. 1 ill.

Description

The invention relates to the field of electrical engineering and can be used in all sectors of the national economy to protect against the corrosion of metal surfaces of long underground objects.

The purpose of the invention is the effective protection of metal surfaces of long underground objects in alternating zones from electrocorrosion.

This goal is achieved by the fact that in the device containing the EMF source, connected between the protected object and the ground, the comparison device, grounding conductors, reference electrodes, for more effective protection, a linear distributed grounding drive and adjustable resistances made in the form of 2 transistors of opposite types of conductivity, the bases of which are connected to the output of the comparison device, the collectors to the ground electrode, and the emitters to the line wire. A protective cable laid along the route of the protected object can be used as a distributed grounding conductor. The low cost of the proposed device (one emf source is used to power several devices) allows their frequency to be switched on after 3-5 km, which significantly increases the protection efficiency. It has been experimentally established that zones with different laws of change in the potential of the metal shell alternate after 3-5 km.

The drawing shows a block diagram of the proposed device, where 1 is a generator of alternating pulses (emf source); 2 - metal shell of the protected object; 3 - drive (distribution grounding); 4 - voltage (its device; 5 - reference electrode; 6 - adjustable resistance; 7 - earthing switch.

Under the influence of stray currents, the cable sheath may be under different voltages of positive or negative polarity with respect to earth. The cable is not subject to corrosion if the sheath potential is in the range from -0.8 V to -1.4 V; If the potential is greater or less than the specified limit, corrosion is possible if the integrity of the insulation of the protective cover is violated. To compensate for stray currents after 3 ... 5 km, comparison devices 4 are installed, connected between the cable 2 and the reference electrode 5, and ground electrodes 7 connected to the wire 3 (laid in the ground or suspended on the supports of the contact network) through adjustable resistances b. Depending on the potential of the cable sheath, a voltage appears at the output of the comparator 4, which changes the resistance of the ground electrode depending on the magnitude and polarity of this voltage.

For example, with a positive potential on the cable sheath and a damaged protective cover at the output of the comparator, a negative voltage will occur. In this case, the transistor VT1 opens, VT2 closes. If the insulation is damaged, a protective current will flow, which closes along the circuit: generator 1,

wire 3, VT1, earthing switch 7, ground-to-cable sheath resistance, generator 1. With a negative potential on the cable sheath exceeding the permissible value of 1.4 V at the output

the comparator’s potential is positive, VT1 closes and VT2 opens. In this case, the protective current is closed by the circuit: generator 1, cable sheath 2, cable-ground resistance, ground electrode 7, VT2, wire 3, generator 1, establishing potential on the cable sheath from - 0.8 V to -1.4 V at the output of the comparator is zero potential, and both transistors

closed. Compensation of stray currents with protective currents provides sufficient protection of the cable sheath against corrosion.

The use of the invention allows

it is more effective to protect metal shells by rooting protection zones and turning on control devices and grounding conductors more often without breaking insulating covers (switching on comparison devices is carried out in rooms, relay cabinets and input devices), it is more efficient to protect alternating zones for which there are no reliable protection devices. Device

allows constant monitoring of the integrity of the cable sheath and the location of damage by the magnitude and direction of the electric field of the ground electrode. The proposed protection device is not

requires special design work, and can be used both during operation and at the stage of designing cable structures. The device is much cheaper than existing cathode stations

PASK type, as It does not require special power lines, moisture-proof protective enclosures, it contains less power sources, is much easier to maintain due to the lack of complex linear devices.

51809841 b

Claims (1)

The claims are equipped with adjustable devices, the grounding device is made in the form Installation for cathodic protection against a core-linear wire to which grounding conductors, for example, metal sheaths of a cable, are connected to each other during the determination of long underground objects and flaxen sections; a device, an EMF source connected between protecting each adjustable device with an executable object and a grounding device in the form of two transistors with an opposite, including a group of grounding conductors, false types of conductivity, base wherein the reference electrodes and the device are likewise connected to the output of the reference device, characterized in that, for the sake of purpose, the collectors are connected to the ground electrode, and the emitters increase the protection efficiency, while they are connected to the line wire.