RU207332U1 - Protection device for power circuits against the effects of lightning discharges - Google Patents

Abstract

The utility model relates to the field of protection of linear telemechanics systems (SLTM) of main gas pipelines (MG), in particular, to devices for protecting SLTM MG from damage caused by lightning strikes by separating electrical circuits. This utility model contains a drive consisting of an electric motor connected to the power supply network, connected by means of a half-coupling with a dielectric shaft installed in bearings inside a dielectric housing, on which magnets are installed, transmitting EMF to a generator that generates electrical energy for power supply of the communication system and automation of the main gas pipeline , while the length of the dielectric shaft is determined depending on the value of the maximum possible voltage. In addition, to ensure separate power supply to consumers, two or more groups of magnets are sequentially installed on the shaft, which transmit EMF to two or more generators, depending on the need to separate groups of consumers. The technical result of this utility model is to exclude the possibility of damage to SLTM MG equipment caused by hit by lightning.

Description

The utility model relates to the field of protection of linear telemechanics systems (SLTM) of main gas pipelines (MG), in particular, to protection devices SLTM MG from overloads caused by lightning strikes by separating electrical circuits.

To ensure control of the parameters of operation and control of the equipment of the linear part of the MG (ball valves, instrumentation and A, etc.), SLTM is used.

The equipment used in the SLTM (according to ZI1.310.013 RE SLTM Magistral-2) has a nominal input voltage of 220 V, and therefore, to protect the equipment from overloads caused by lightning and / or internal impulse overvoltages, SLTM provides protection systems for input power circuits by using the following components:

automatic switches;

arrester modules;

mains isolation transformer;

fuse and varistor (built into the power supply).

At the same time, the technical characteristics of the applied protections are such that the aforementioned elements have limited characteristics not exceeding (including according to the data of component manufacturers and other reference data):

1. at lightning strikes 2.5 kV at 5 kA (withstand 20 strikes at the upper current threshold). When studying the technical characteristics of the installed arresters, the maximum current strength, as a rule, cannot exceed double the value of the upper current threshold, i.e. 10 kA with a smaller (possibly single) exposure;

2. No specific characteristics are given for the protection of input power circuits. If we consider the characteristics of the individual constituent elements of the structure, then the following picture can be seen:

the minimum operation time of the circuit breaker may not be less than 10 ms, while the current must reach values exceeding the set values by 100 times. With a smaller value of the passing current, the response is greater;

the minimum response time of the fuse-link (installed in the SLTM power supply unit) cannot be less than 10 milliseconds, while the passing current must exceed the set 20 times. Accordingly, at a lower current, the response time is also longer, as in the case of circuit breakers.

As practice has shown, an increase in the input supply voltage to values exceeding 250 V (in the event of a break in the "zero" of the three-phase wiring), nothing catastrophic happens - the protection of the power supply is triggered: the varistor closing the input circuits entails a blown out of the fuse of the power supply - the system turns out to be disconnected from the network.

When lightning strikes power lines, as practice has shown, the available means of protection are often insufficient: under the influence of impulses, the voltage and current strength of which many times exceeds the values of the existing protections, not only the input protective circuits and the power supply fail, but also the SLTM itself , since high impulse voltages freely pass through the input protection circuits (destroying and / or damaging them, or simply existing protections do not have time to operate due to the very short duration of the lightning discharge), then through the inductive coupling of the isolation transformer and the power supply transformer (and / or air gaps of these transformers) and, as a result, damage the SLTM itself - the power supply, signaling, measurement (control) circuits, as well as sensors and devices are damaged.

No other known devices for protection of SLTM circuits (than those used in standard solutions for SLTM protection), which would provide full protection against lightning discharges, have not been found in the literature or in the public domain.

At the same time, there is RF patent 2440634, which describes a device for transmitting electrical energy and information. The main disadvantage of the analogue is the use of a transformer as a galvanic isolation. Thus, this solution has the same disadvantages as the standard solutions used in the SLTM Magistral-2.

The technical result of this utility model is expressed in the exclusion of the possibility of damage to the SLTM MG equipment caused by lightning strikes.

The technical result achieved is achieved by the fact that to protect the equipment of SLTM MG, the power lines and power circuits of the SLTM are separated by transferring electrical energy from the network to mechanical, and then back - from mechanical to electrical, for the SLTM power circuits. This solution excludes the passage of lightning discharges through the inductive coupling of transformers and spark gaps in the structures of devices and the system as a whole, which are available in standard solutions.

The device is a drive consisting of an electric motor connected to the power supply network, connected by means of a half-coupling with a dielectric shaft installed in bearings inside a dielectric housing, on which magnets are installed, transmitting EMF to a generator that generates electrical energy for power supply of SLTM MG equipment, while the length the dielectric shaft is determined depending on the required value of the maximum possible voltage.

The design and principle of operation of the utility model are shown in Fig. 1.

FIG. 2 shows a block diagram of a device for galvanic isolation of power supply circuits with several consumers. The number of galvanically isolated consumers can be increased by increasing the generator groups.

FIG. 3 shows the connection diagram of the CP SLTM for comprehensive protection against the effects of lightning discharges that enter both power lines and equipment installed on the main pipeline.

FIG. 1 denoted: 1 - housing made of dielectric material, 2 - plugs, 3 - bearings, 4 - shaft made of dielectric material, 5 - magnets (fixed with alternating field orientation on the shaft (4)), 6 - coils of copper wire wound on magnetic circuits , 7 - electric motor, 8 - half couplings, 9 - elastic element.

FIG. 3 shows a complex circuit that provides galvanic isolation to protect against the effects of lightning discharges in the power supply circuits and circuits of the main and peripheral equipment.

The principle of operation of the utility model shown in FIG. 1: the voltage from the mains is supplied to the electric motor (7), which, through the half-couplings (8) and the elastic element (9), rotates the shaft made of dielectric material (4) installed inside the housing (1) in bearings (3). By rotating the magnets (5) mounted on a shaft made of dielectric material (4), we obtain EMF on coils made of copper wire (6), which, after straightening and stabilization, is supplied to consumers.

The level of protection against arising overvoltages in the network between the circuits on the side of the power line (electric motor) and consumer circuits (generator) according to FIG. 1 is determined by the length L of the dielectric part of the structure, measured between the wound coils (we assume the worst conditions - coils without filling; wire insulation is not taken into account): the longer, the higher the level of protection. So, with a length of L = 200 mm, protection is provided against a voltage level measured in tens and hundreds of thousands of volts (depending on the state of the environment, the presence or absence of insulation in electromagnets, the duration of the discharge pulses, etc., etc.).

Under normal conditions, we calculate the value of the air breakdown voltage using the formula proposed by Friedrich Paschen:

постоянная

where: constant

constant

relative air density

Substituting the values into the formula, we get:

In conditions of high humidity, or changes in the frequency (duration) of lightning impulses, the voltage value may decrease, but in any case, these values will certainly be higher than the breakdown distances along other discharge paths: for grounding buildings, structures, etc., which will ensure the safety of critical systems from overvoltage.

Shown in FIG. 3 is a complex circuit, it works as follows: the voltage from the mains is supplied to the electric motor, which rotates the shaft with permanent magnets installed on it. An EMF arises on the coils of the generator groups, which is supplied after rectification and stabilization to consumers. The level of protection against arising overvoltages in the network between the circuits on the side of the power line (electric motor) and the circuits of consumers (electric generators) is determined by the lengths L1 and L2 (Fig. 3), the calculation of which is similar to that given above in Fig. 1. A high level of breakdown voltage protection guarantees the outflow of the arising lightning discharges along other paths: to the grounding of buildings, structures, etc., which will ensure the safety of critical systems from overvoltage. Protection of the impact of lightning discharges through the signaling and control circuits is provided by ADC / DAC converters and FOCL that do not contain conductive elements.

Claims (2)

1. A device for protecting power circuits from the effects of lightning discharges, containing a drive, which is an electric motor connected by means of a half-coupling with a dielectric shaft mounted on bearings inside a dielectric housing, permanent magnets are installed on the dielectric shaft, which induce the EMF in the generator coils when the shaft rotates installed on the body for power supply of the communication system and automation of the main gas pipeline, while the length of the dielectric shaft is determined depending on the value of the maximum possible voltage. 2. A device for protecting power circuits from the effects of lightning discharges according to claim 1, characterized in that two or more groups of magnets are sequentially installed on the dielectric shaft, which transmit EMF to two or more generators, which in turn provide separate power supply to communication systems, automation and other potential consumers.

Images