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High Electric and Magnetic Field Engineering. Cable Engineering
UDC 621.3.022: 621.319.53: 537.311.8 doi: 10.20998/2074-272X.2018.5.08
M.I. Baranov, S.G. Buriakovskyi, S.V. Rudakov
THE METROLOGY SUPPORT IN UKRAINE OF TESTS OF OBJECTS OF ENERGY, AVIATION AND SPACE-ROCKET ENGINEERING ON RESISTIBILITY TO ACTION OF PULSES OF CURRENT (VOLTAGE) OF ARTIFICIAL LIGHTNING AND COMMUTATION PULSES OF VOLTAGE
Purpose. Presentation and analysis of the modern state of the metrology support in Ukraine of model tests of equipment of objects of energy on resistibility to the action of pulsed current (voltage) of artificial lightning and commutation pulses of voltage, and also objects of aviation and space-rocket engineering on resistibility to lightning. Methodology. Electrophysics bases of engineering of high-voltage and large pulsed currents, theoretical bases of the electrical engineering, technique of the strong electric and magnetic fields, and also measuring technique. Scientific methods of analysis of scientific and technical information. Results. Information is resulted, touching the modern consisting of Ukraine of providing high-voltage measuring facilities conducted on requirements of the normative documents of the USA of SAE ARP 5412:2013, SAE ARP 5416:2013, International Standard of IEC 62305-1:2010 and Standard GOST 1516.2-97 model tests of equipment of objects of energy on resistibility to lightning and commutation resistibility, and also objects of aviation and space-rocket engineering on resistibility to lightning. It is marked that similar measuring facilities are not made by domestic industry. It is indicated that R&DPCI «Molniya» of the NTU «KhPI» disposes the proper measuring facilities of the own making, passing a state metrology check (calibration). Basic technical descriptions are described developed and created at this Institute: high-voltage high-current shunts of type of SC-300M1 and SC-300M2, intended for measuring of micro- and millisecond pulses of current amplitude to ±220 кА with the integral of their action to 15106 J/Ohm; capacitive (type of CDV-100 and CDV-1,2) and ohmic (type of ODV-1,2 and ODV-2,5) dividers of pulsed voltage of micro- and millisecond duration, capable not only to measure but also form on the tested electric loading standard (nonstandard) storm and commutation pulses of voltage amplitude to ±2 MV. Originality. First in the generalized kind possibilities are developed and created by the domestic scientific and technical workers of high-voltage high-current measuring facilities, intended for the aims of the metrology providing of model tests in obedience to the requirements of domestic and foreign normative documents of equipment of objects of energy on resistibility to lightning and commutation resistibility, and also objects of aviation and space-rocket engineering on resistibility to lightning. Practical value. Application in practice of model tests on powerful highvoltage pulsed current (voltage) of artificial lightning and commutation pulses of voltage of electrical equipment and component elements of objects of energy, aviation and space-rocket engineering on resistibility to lightning and commutation resistibility of the described special high-voltage measuring facilities will be instrumental in the decision of global in the world problem of protection from lightning of ground and air-based technical objects and to the increase of their strength security. References 23, tables 4, figures 16.
Key words: high-voltage generators of pulses of current (voltage) of artificial lightning and commutation pulses of voltage, objects of energy, aviation and space-rocket engineering, measuring facilities for the model tests of technical objects on resistibility to the action of pulses of current (voltage) of artificial lightning and commutation pulses of voltage.
Изложено современное состояние метрологического обеспечения в Украине натурных испытаний объектов промышленной энергетики, авиационной и ракетно-космической техники на стойкость к прямому воздействию на них мощных импульсов тока (напряжения) искусственной молнии и апериодических коммутационных импульсов напряжения. Показано, что подобные испытания технических объектов на молниестойкость и коммутационную стойкость могут проводиться в соответствии с требованиями нормативных документов США SAE ARP 5412: 2013, SAE ARP 5416: 2013, международного стандарта IEC 62305-1: 2010 и стандарта ГОСТ 1516.2-97 в полевых условиях на уникальных отечественных высоковольтных сильноточных электроустановках, оснащенных современными измерительными средствами. Описаны основные технические характеристики разработанных и созданных в НИПКИ «Молния» НТУ «ХПИ» для метрологического обеспечения натурных испытаний указанных технических объектов на молниестойкость и коммутационную стойкость: измерительных коаксиальных сильноточных шунтов типа ШК-300М1 и ШК-300М2, емкостных и омических высоковольтных и сверхвысоковольтных делителей напряжения типа ЕДН-100, ЕДН-1,2, ОДН-1,2 и ОДН-2,5. Приведены примеры практического использования при натурных испытаниях на молниестойкость и коммутационную стойкость отмеченных технических объектов указанных нестандартизованных измерительных средств собственного изготовления. Библ. 23, табл. 4, рис. 16. Ключевые слова: высоковольтные генераторы импульсов тока (напряжения) искусственной молнии и коммутационных импульсов напряжения, объекты энергетики, авиационной и ракетно-космической техники, измерительные средства для натурных испытаний технических объектов на стойкость к действию импульсов тока (напряжения) искусственной молнии и коммутационных импульсов напряжения.
Introduction. In accordance with the requirements of the current US regulatory documents SAE ARP 5412:2013 [1], SAE ARP 5416:2013 [2] and International Standard IEC 62305-1:2010 [3] for field testing of aviation, rocket and space equipment and power objects to lightning resistibility to the latter pulses of artificial lightning current with different amplitude-time parameters (ATPs) from powerful high-voltage lightning
current generators (LCG) are applied. In this case, the amplitudes ¡„l of lightning current pulses flowing through the test objects can vary from tens of Amperes to hundreds of thousands of Amperes, and their duration tp is from hundreds of microseconds to one thousand milliseconds [1-3]. In the documents [1-3], the numerical values of the normalized ATPs used in the tests for the
© M.I. Baranov, S.G. Buriakovskyi, S.V. Rudakov
lightning resistibility of the considered technical objects of the current pulses of artificial lightning are described in more detail. In [4], the authors described the technical characteristics of unique domestic powerful high-voltage LCG, which realizes the requirements of documents [1-3]. The current Standard GOST 1516.2-97 [5] defines normalized ATPs of voltage pulses of lightning nature and commutation aperiodic voltage pulses used in testing the electrical strength of external (internal) insulation of industrial power engineering objects with capacitive characteristics (for example, switches, disconnectors, bushings, insulators, current transformers, capacitors, etc.). In this case, the thunderstorm aperiodic voltage pulse generated on the tested load by the pulsed voltage generator (PVG), constructed according to the classical Arkadiev-Marx scheme, is characterized by the time shape t/tp=1.2 ^s/50 ^s (with tolerances on: front Tf ± 30 %, voltage amplitude UmL ± 3%, pulse duration tp at the level 0.5 UmL ± 20%), the normalized maximum value of which UmL usually does not exceed 1 MV [5]. We point out that the amplitude Umk of commutation aperiodic voltage pulses, reproduced on electric load by the commutation voltage pulse generator (CVPG), reaches a level of several Megavolts. The time of rise Trise of such voltage pulses to the level Umk is several hundred microseconds, and their duration TP at the level of 0.5 Umk is up to several thousand microseconds [5]. For the prompt registration of the ATP of the specified current and voltage pulses, appropriate measuring means are required. It should be noted that the domestic industry does not produce such measuring aids. In this regard, the developers and creators of LCG, PVG and CVPG, as well as the operating engineering and technical personnel serving them, are required to independently solve the problems of metrology support of contractual works and applied scientific research carried out with the help of these high-voltage current and voltage generators in the considered relevant worldwide scientific and technical field of engineering and electrophysics of high currents and high (superhigh) voltages.
The goal of the paper is the presentation and analysis of the current state of metrology support in Ukraine of testing equipment of industrial power facilities for lightning resistibility and commutation stability, as well as for aviation and rocket and space equipment for lightning resistibility.
1. Metrology support of testing of technical objects for lightning resistibility. First, let us dwell on the issues of metrology support for the testing of aviation and rocket and space equipment and energy facilities for resistibility to the impact of artificial lightning current pulses on them. For aircraft and rocket and space equipment, such tests are regulated by the requirements of US regulations SAE ARP 5412:2013 [1] and SAE ARP 5416:2013 [2]. According to [1, 2], the following components of the artificial lightning current generated in high-voltage high-current LCG circuits can flow through the tested objects of the indicated technique: pulsed A- (or repetitive pulsed D-), intermediate B- and prolonged C-(or shortened long C* -) components of artificial lightning current. The main ATPs of the component of the pulsed current of artificial lightning are given in Table 1. The
following combinations of these lightning current components are most often used [1, 2, 6]: A-, B- and C-components; A-, B- and C*- components; D-, B- and C*-components.
Table 1
Normalized ATPs of the main components pulsed current of artificial lightning [1, 2, 4]
Artificial lightning component ImL, kA Ic, kA qi, C Jl, 106 J/Q ^s Tp, ms
A 200±20 - - 2±0.4 <50 <0.5
B - 2±0.4 10±1 - - 5±0.5
c 0.2-0.8 - 200±40 - - (0.25-1)-103
C* - 0.4 6-18 - - 15-45
D 100±10 - - 0.25±0.05 <25 <0.5
Note. ImL is the amplitude of the current pulse; Ic is the average value of the current; qL is the amount of electric charge leaking through the object under test; JL is the integral of the action of the current pulse; Tf, tp are, respectively, the pulse front duration between the levels (0.1-0.9) ImL and the current pulse at the level <0.1ImL.
For industrial power facilities, the high-voltage high-current tests for lightning resistibility under consideration are governed by the requirements of the International Standard IEC 62305-1:2010 [3] and the national Standard GOST R IEC 62305-1:2010 [7] developed in Russia on this basis. An aperiodic pulsed current of artificial lightning of the time shape t/tp=10 ^s/350 ^s of both polarities, characteristic of a direct short thunderstorm attack to terrestrial objects protected by a number of engineering services of power supply companies, is fed from the powerful LCG to the test object. Table 2 shows the main ATPs of this powerful test current pulse of artificial lightning.
Table 2
Normalized ATPs of the aperiodic current pulse of lightning of temporary shape 10 ^s/350 ^s [3, 4]
Name of the lightning current pulse parameter Lightning protection level of the facility according to the Standard IEC 62305-1: 2010
I II III-IV
Front duration t, ^s 10±2 10±2 10±2
Pulse duration at half-descend tp (at the level 0.5Imi), ^s 350±35 350±35 350±35
Current amplitude ImL, kA 200±20 150±15 100±10
Integral of action JL, 106 J/Q 10±3.5 5.6±1.96 2.5±0.875
Charge qL, C 100±20 75±15 50±10
With regard to testing the electrical strength of external and internal insulation of power facilities to the effects of lightning discharges, according to [5], they are carried out using the above-mentioned thunderstorm voltage pulse of the time shape 1.2 ^s/50 ^s. In this case, for its measurement we can use measuring standard balls with a diameter from 125 mm to 1.5 m [8], as well as high-voltage capacitive (CDV) and ohmic (ODV) dividers of voltage for pulsed voltages of ±(0.1-2.5) MV, having in the composition of high-voltage and low-voltage arms [5, 9].
1.1. Measuring coaxial disk shunts type SC-300M1 and SC-300M2. To record the current pulses of
artificial lightning with the ATPs according to the data of Table 1, 2, generated at the objects under test with powerful LCG [4], satisfying the requirements [1-3], special measuring high-voltage high-current disk shunts of SC-300M1 (Fig. 1) and SC-300M2 (Fig. 2) type of the coaxial design were developed and created at the R&DPCI «Molniya» of the NTU «KhPI». Similar shunt designs are characterized by their small inductance values (not more than 10 nH) and active resistance (no more than 0.2 mQ), which provides insignificant influence of the own electrical parameters of the measuring shunt on the electromagnetic processes occurring in the load. A significant difference between the designs of these high-current shunts from known (for example, described in [6]) is the use in them instead of a thin-walled (with a thickness of not more than 0.3 mm) high-resistance manganin disk from which the drop in the pulsed voltage from the passage of a measured current pulse is taken, a disk of thickness of 1 to 2 mm from stainless steel 12X18H10T [10, 11].
Fig. 1. External view of the improved coaxial disk shunt type
SC-300M1, intended for measurement in the micro- and millisecond ranges of damped sinusoidal and aperiodic current pulses of artificial lightning with amplitude up to ±220 kA in the high-current discharge circuit of a powerful high-voltage LCG with their integral of action up to 3-106 J/Q [10]
Fig. 2. External view of the improved coaxial shunt type SC-300M2 designed to measure in the coordinated mode of operation of its cable signal transmission line in the micro- and millisecond ranges of current pulses of artificial lightning with amplitude up to ±220 kA in the high-current discharge circuit of high-voltage LCG with their integral of action up to 15106 J/Q [11]
Such a technical improvement of the design of the high-resistance measuring disk in the high-voltage high-current shunt (see Fig. 1, 2) has made it possible to significantly increase its electrothermal resistivity to high impulse currents (HICs) flowing along it and to avoid the development of the phenomenon of electric explosion (EE) of its metal dangerous for the mechanical stability of the shunt.
As is known [12, 13], the EE of the metal measuring disk of the shunt at registration of the HIC is accompanied by a sharp increase in the gas-dynamic pressure inside the shunt (up to hundreds of atmospheres [14]), usually leading to its destruction and failure. Fig. 3 is a schematic view of a shunt of the SC-300M2 type in the longitudinal section.
6 8 5 7
Fig. 3. Schematic view of the design of a coaxial disk shunt of the SC-300M2 type in its longitudinal axial section (1 - a massive inner cylindrical brass electrode, 2, 3 - an insulating sleeves made of fluoroplastic, 4 - a massive outer cylindrical brass electrode, 5 - a measuring high-resistance steel disk, 6, 7 - massive clamping insulating disks, 8 - banded brass disk, 9, 10, 12 - steel fastening screws, 11 - CP-75 output
coaxial connector, 13 - massive clamping brass ring, 14, 15 - respectively input (potential) and output (grounded)
elements of the brass bolt connection of the shunt to the high-voltage high-current discharge circuit of the LCG) [11]
For the simultaneous measurement of several components of the total current of artificial lightning generated in a high-voltage high-current discharge circuit of the LCG, it was required to develop and create a special measuring matching voltage divider (MVD), which is connected to the output of an additional shielded coaxial communication line (Fig. 4). In the shown in Fig. 4 divider of the type SDN-300 there are two coaxial connectors 1:1 and 1:2, intended for the coordinated connection of their outputs to the inputs of the measuring channels of digital storage oscilloscopes (DSO) [6, 10].
Fig. 5 is a general view of the placement of three DSO type Tektronix TDS 1012 in a buried screened measuring hopper for field testing of aircraft equipment for direct impact in them according to [1, 2] of lightning current.
Fig. 4. External view of the SC-300M1 measuring shunt connected to the input of an additionally shielded coaxial RF cable of the RK 75-7-11 type with a length of 70 m, the output of which is connected to a shielded matching voltage divider of the type SDN-300 with two output coaxial connectors 1:1 and 1:2 for the coordinated connection of the measuring channels of
the three DSO (for example, Tektronix TDS 1012 series) to them, while simultaneously registering of three components of
the total current pulse of the artificial lightning in the high-current discharge circuit of the LCG with different ATPs [6, 10]
Table 3
The main technical characteristics of high-voltage high-current shunts SC-300M1 and SC-300M2
Shunt name Characteristic value
RS, mfl Ks, A/V Mass, kg
SC-300M1 0.158±1 % Ks4=12625 3.1
Ksc=6312
SC-300M2 0.080±1 % Ksa=25000 3.2
Ksc=12500
Note. RS is the active resistance of the shunt disk, mfl; KS=2/RS is the shunt transform coefficient, A/V; KSA is the shunt conversion factor for measuring in the discharge circuit of the LCG of the ATPs of a- and d- components of the lightning current and lightning pulse of the shape 10 ^s/350 ^s, A/V (from the 1:1 coaxial connector of the SDN-300 divider); KSC is the shunt conversion factor when measuring in the discharge circuit of the GTM of the ATPs of b-, C- and c*- artificial lightning current component, A/V (from the coaxial connector 1:2 of the SDN-300 divider).
1.2. Capacitive and ohmic voltage dividers type CDV-100, CDV-1,2, ODV-1,2 and ODV-2,5. In 2011, when studying the behavior of high-voltage insulation samples (in particular, wood) of test electrical installations of Department No. 4 of the Institute under the influence of large pulsed currents and high voltages on them, we found it necessary to have a small mobile capacitive voltage divider of amplitude up to ±100 kV (CDV-100) operating in the microsecond time range. Fig. 6 shows the connection diagram of the CDV-100 to the measuring circuit of the installation.
Uv
ll -i- Chv
Cu-^
Fig. 5. External view of the placement of three Tektronix TDS 1012 digital storage oscilloscopes that register in parallel useful electrical signals from one SC-300M1 measuring shunt in a buried screened measuring hopper designed for metrology support of field testing of various technical objects for lightning resistibility [9]
It should be noted that the DSO used by us in testing technical facilities for lightning resistibility have the corresponding certificates of metrological verification and calibration of the State Enterprise «Kharkivstandartmetrologiya» (for example, No. 08/2128K dated May 16, 2017).
Table 3 shows the main technical characteristics of the described shunts of the type SC-300M1 and SC-300M2 that passed the state metrological certification at the State Enterprise «Kharkivstandartmetrologiya» (inspection certificate No. 06/184 of June 27, 2017 and certificate of conformity No. 06/0206 of July 19, 2017) [11].
Using the data of Table 3 and the readings (in fractions or units of volts) recorded on the screen of the DSO from the measuring shunt of the drop of the US pulsed voltage, the required value of the measured lightning current pulse I„i is determined as: ImL —Kg" Ug.
rc
HQ RC .)
-I- Civ
Rc
I
X
ul
13-
Fig. 6. Connection diagram of CDV-100 to the input of the DSO [15]
The measurement circuit in Fig. 6 of the high voltage UV applied to the high-voltage divider arm with capacitance Chv, connected in series with the low-voltage divider arm of with capacitance Clv>>Chv, is based on the agreed operating mode of the CDV-100 measuring circuit. To implement this mode, the coaxial RF cable (PC) with the impedance ZB of the transmission line of the useful electrical signal from the low-voltage arm of the RC=ZB matching impedance divider and the connection on the low-voltage side of the circuit with the voltage UL of the matching RCCC chain are used in the circuit of the wire (see Fig. 6). We indicate that the connection of the resistance RC in accordance with the circuit in Fig. 6 reduces twice the useful signal with the level of voltage UL applied to the measuring channel of the DSO. To improve the transmission characteristics of the divider under consideration, its low-voltage arm contains a
corrective RkCk chain. In accordance with the circuit of Fig. 6 the following numerical values of the main electrical parameters of the CD V-100 divider were used (Fig. 7): Chv=0.47 nF; Clv=Cc=0.54 ^F; RC=ZB=75 Q; Rk=27 Q; Ck=2.8 nF.
We point out that high-voltage ceramic capacitors of the K-15-10 type (with a capacitance of 4700 pF for a rated voltage of ±50 kV) were used to create a highvoltage arm of the CDV-100 pulsed voltage divider. In this connection, the capacitance Chv consisted of 10 series-connected capacitors of the indicated type, placed in air in an insulating pipe made of glass textolite of STEF brand (length of 915 mm and inner diameter of 151 mm with wall thickness 12 mm). The low-voltage arm of the divider under consideration with capacitance of Clv=0.54 ^F was realized on the basis of two parallel capacitors of the K-73-11 type with capacitance of 0.27 ^F at a voltage of 250 V [15]. The matching active resistance RC was assembled from two parallel-connected resistors of the MLT-2 type with a rating resistance of 150 Q. The electrical part of the low-voltage arm of the described divider was placed in a rectangular aluminum casing with a CR-75 coaxial connector rigidly fixed to the isolator base of the divider and connected to the grounding bus of the test setup. The calculated value of the division factor for CDV-100 in the circuit according to Fig. 6 was numerically KD1=2Clv/Chv=2298. The performed high-voltage experiments showed that the experimental value of the CDV-100 division factor is KD2~2515 [15].
Fig. 7. General view of the mobile high-voltage pulsed voltage divider CDV-100 for a rated voltage of ±100 kV, placed on the test field of a superhigh voltage pulsed voltage generator of the GIN-1,2 type of our own flooring design (the GIN-1,2 generator is located behind the CDV-100 divider; to the right of the CDV-100 divider there are movable standard measuring balls with a diameter of 125 mm) [15]
In Fig. 8 shows the electrical circuit with the use of a high-voltage capacitive voltage divider of the type CDV-1,2, designed to form a non-standard commutation aperiodic pulse of a time shape of 250 ^s/5000 ^s of amplitude up to ±1 MV in the long air gap between the electrodes E1 (disk) and E2 (rod) [16]. In this circuit, the CDV-1,2 divider at a nominal voltage of ±1.2 MV performs not only the role of the measuring mean, but also the role of the superhigh voltage forming capacitance.
Rg
zCg
E,
_. Chv
Rd CDV-
E,
1,2 :
I
Cv
-EO
R,
DCVI
Fig. 8. A schematic electrical circuit for the forming in the GIN-1,2 type generator discharge circuit in a long air gap of a commutation aperiodic voltage pulse of a time shape of 250 ^s/5000 ^s with an amplitude up to ±1 MV based on the use of a capacitive voltage divider of the CDV-1,2 type [16]
In the circuit according to Fig. 8 to the potential electrode E of the air gap from the DC voltage installation (DCVI) through a protective resistance Rp of 1.4 GQ (14 resistors of the KEV-5-100 MQ type with a total length of 2.05 m), a DC voltage of up to ±50 kV can be applied. The generator of pulsed voltages of type GIN-1,2 had following own electric parameters [16]: Rg=48 Q; Lg=6 ^H; Cg=20.8 nF; discharge resistance Rd=340 kQ. The front active resistance Rf, connected to the circuit in Fig. 8 between the cut-off K and the isolating K2 switches was 360 kQ. The capacitance Chv of the highvoltage arm of the divider CDV-1,2 was chosen equal to 130 pF, and the capacitance Ctv of its low-voltage arm, connected to the oscilloscope or DSO, was 2.6 ^F. At the same time, the calculated division factor for CDV-1,2 had a numerical value equal to KDC = ClvChv=20-103 [16].
Fig. 9 shows a general view of a high-voltage test stand, which uses as a base of its design the electrical circuit in accordance with Fig. 8 with a capacitive voltage divider of the type CDV-1,2.
Fig. 10 shows a general view of the ultrahigh-voltage ohmic voltage divider ODV-1,2 developed and created at the Department No. 4 of the Institute.
The insulating supporting structure (ISS) of the divider ODV-1,2 is assembled from five rigid hollow fiberglass sections fixed in a single rack, inside which high-voltage ceramic resistors of the type TV0-5-250 Q were placed on the getinax plates [17]. Each divider section contains 40 consistently and zigzag connected on both sides of the getinax plate of the indicated resistors with a total active resistance of 10 kQ. In the case of using the four specified sections in the divider, the design of an ohmic divider of the ODV-1 type for a nominal voltage of ±1 MV (Fig. 11) can be realized [17].
L
g
Fig. 9. General view of the high-voltage test stand of the R&DPCI «Molniya» of the NTU «KhPI», intended for testing lightning protection equipment of technical objects with commutation aperiodic voltage pulse with amplitude up to ±1 MV of time shape 250 ^s/5000 ^s and containing in the scheme a mobile superhigh voltage capacitor voltage divider of the type CDV-1, 2 [16]
Fig. 10. General view of a mobile superhigh-voltage ohmic voltage divider of the type ODV-1,2 at a rated voltage ±1.2 MV, located at the factory test field of a high-voltage test stand SVI-1,2, designed to determine in the laboratory conditions the pulsed electrical strength of polymer insulation of its own production (enterprise ES «Polymer», Bakhmut city, Ukraine, 2006) [9, 17]
Fig. 11. General view of the high-voltage test stand of the R&DPCI «Molniya» of the NTU «KhPI», on the test field of which mobile generator of pulsed voltages of the type GIN-1,2, the divider of the type ODV-1 and standard measuring balls with a diameter of 250 mm are placed [17]
For the divider of the type ODV-1,2, the highvoltage arm is characterized by an active resistance Rhv=50 kQ. Its low-voltage arm is made of two parallel-connected resistors of the MLT-2 type with a total active resistance Rlv=2.5 Q. In this connection, the calculated division factor for the divider ODV-1,2 is KDR=Rhv/Rlv=20-103. In practical use in the measuring path, connected to the low-voltage arm of a divider of the type ODV-1,2, the matching circuit, which is similar to that shown in Fig. 6, the coefficient of its division KDR is doubled and numerically is about 40-103. Experimental verification of the KDR value using standard balls of diameter of 250 mm (see Fig. 11) according to the requirements of [8] showed that it takes a numerical value of about 39.8-103. From Fig. 10, 11 it can be seen that above the ISS of dividers of the type ODV-1,2 and ODV-1, anti-crown metal shields are installed, which simultaneously improve the distribution of a strong electric field along their upper sections [17].
The use in the discharge circuit of shown in Fig. 8, 11 the generator of pulsed voltages of the type GIN-1,2 at a rated voltage of ±1.2 MV with an own discharge resistance R^=240 kQ and an additional shaping resistance R/7=1.98 kQ (Fig. 12) of the ohmic voltage divider of the type ODV-1,2 (or ODV-1) makes it possible to form following requirements [5] a standard lightning aperiodic wave of a voltage of 1.2 ^s/50 ^s with the above tolerances and the required values of its amplitude UmL<±1 MV [16, 18]. Here, the capacitive nature of the load (CL~10 pF) and the parasitic capacitance of the ODV-1,2 divider, approximately 50 pF, should be taken into account in the calculation circuit for the formation of a standard lightning pulse of the shape 1.2 ^s/50 ^s.
Rr
R
fl
Rr
Ri
K,
E-d2
1
R
f2
Fig. 13. Electric circuit for obtaining in the discharge circuit of
the generator GIN-1,2 on the tested load with the capacitive characteristic of a standard commutation pulse of a time shape of 250 ¡s/2500 ¡s with the use of a capacitive voltage divider of the type CDV-1,2 with a total capacitance CD=130 pF (R^=240 kH is the own discharge resistance of the GIN-1,2;
Rd2=840 kH is the additional discharge resistance of the GIN-1.2; Rg =48 H; Cg=20.8 nF; Rj2=395 kH; CL=10 pF ; K2 is the cut-off high-voltage switch of the generator GIN-1,2) [9, 18]
To measure with an error of no more than 5 % at industrial power facilities of aperiodic lightning and commutation voltage pulses up to ±2.5 MV, an ultrahigh-voltage ohmic voltage divider of the ODV-2,5 type was created in the Department No. 4 of the Institute [19, 20]. The main technical characteristics of this pulsed voltage divider are given in Table 4 [20].
Table 4
The main technical characteristics of a superhigh-voltage ohmic voltage divider ODV-2,5
Fig. 12. Electric circuit for obtaining in the discharge circuit of the generator GIN-1,2 on the tested load with the capacitive characteristic of a standard lightning voltage pulse of the time shape of 1.2 ¡is/50 ¡s with the use of the ohmic voltage divider of the type ODV-1,2 with an active resistance RD=50 kQ (Rd=240 kQ is the own discharge resistance of GIN-1,2, Rd1=3.91 kQ is the additional discharge resistance of GIN-1,2;
Rg=48 Q; Cg=20.8 nF; R/J=1.98 kQ; CL=10 pF; C,=50 pF) [9, 18]
The utilization in the discharge circuit of the pulsed voltage generator of the GIN-1,2 type to a rated voltage of ±1.2 MV of a capacitive voltage divider of the CDV-1,2 type (Fig. 13) allows on the electrical load under test with the indicated capacitive characteristic (CL=10 pF) to form a standard commutation pulse of voltage of a time shape of 250 ¡s/2500 ¡is with an amplitude ^<±700 kV with normalized tolerances (for a rise time ±20%, for a half-decay time ±30%, for the amplitude Umk ±3 %) [5, 18]. It should be noted that the mobile capacitive voltage divider CDV-1,2 contains three C- sections connected in series, each of which is placed in a 900 mm diameter glass-fiber plastic pipe of TSEF brand with an outer diameter of 300 mm with a wall thickness of 35 mm. Each of its C- sections consists of 12 series-connected high-voltage ceramic capacitors of type K 15-10-4700 pF at ±50 kV. Each of these sections of the divider is filled with transformer oil of T-1500 grade, and its upper and lower terminals are connected to round metal flanges with a diameter of 350 mm [16, 18].
No. Characteristic name Value
1 The maximum level of the measured voltage Um, kV ±2500
2 The active resistance of the high-voltage divider's arm Rhv, kQ 107.3
3 The active resistance of the low-voltage divider's arm Rlv, Q 4
4 Division coefficient, KDR 26.82-103
5 Height (length), m 12.6
6 Mass, kg 350
General view of a superhigh-voltage ohmic voltage divider of the type ODV-2,5, functioning as a part of a unique CVPG at ±2.5 MV, is shown in Fig. 14. The high-voltage arm of the ODV-2,5 divider is made up of nine R- sections connected in series and placed outside and inside the glass-fiber pipe of the TSEF brand with an outer diameter of 120 mm and a wall thickness of 10 mm. Each R- section contains 20 series-parallel-connected high-voltage ceramic resistors of the TVO-10-2,4 kQ type, assembled on two glass-fiber plates with a length of 1400 mm and a thickness of 5 mm. As a result, the resistance of each section of the high-voltage divider arm is about 12 kQ, and its total resistance is Rhv=107.3 kQ [20].
Fig. 14. General view of a superhigh-voltage ohmic voltage divider of the ODV-2,5 type for a rated voltage of ±2.5 MV, connected in the CVPG discharge circuit to a two-electrode «needle-plane» system with an air gap length of 3 m (the upper steel rod-electrode of this electric discharge system is located at the center of its lower flat electrode made of thin galvanized steel with a plan size of 5 m x 5 m) [23]
The low-voltage arm of the ODV-2.5 divider is made of small-sized ceramic resistors of the TBO-2-2 Q
type with a total active resistance Rlv=4 Q. In this connection, the calculated division coefficient KDR for the considered voltage divider of the type ODV-2,5 is approximately equal to KDR=Rhv/Rlv=26,82-103. With the agreed mode of measuring the pulsed voltage on the load, the division coefficient for the divider of the type ODV-2,5 will be doubled and take a numerical value of about 53,65-103. An experimental estimate of the reaction time TR of the ohmic divider of the type ODV-2,5 on the action of a rectangular voltage pulse [21] showed that for this type of divider Tr^ 170 ns [19]. In this regard, the voltage divider of the type ODV-2,5 can be used to measure voltage pulses with an amplitude of Um<±2.5 MV, varying in micro- and millisecond time bands. A comparison of the metrological characteristics of a superhigh-voltage ohmic divider of the ODV-2,5 type with the characteristics of the known high and ultra high voltage meters [22] indicates that the domestic voltage divider of the ODV-2,5 type meets modern requirements and developments in the field of high-voltage measuring equipment.
Fig. 15 shows the oscillogram of a superhigh-voltage pulse of microsecond duration, obtained with the help of the ohmic voltage divider of the ODV-2,5 type on a long air gap of 3 m at its electrical breakdown in the «rod-rod» system [20]. From the oscillogram of Fig. 15 it can be seen that the cut-off voltage Uc in our case is approximately Uc ~ 25 V x 53.65-103 ~ 1341.3 kV. Here, the pre-discharge time TC for this insulating air gap is about TC~5 x 2.5-10-6 s^12.5 ^s, and the cut-off time TDC of the microsecond voltage wave does not exceed the value 5.47 ^s.
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Fig. 15. Oscillogram of a superhigh voltage pulse of positive polarity on the air gap of 3 m long in a «rod-rod» system cut at its rising part and registered with the ohmic voltage divider ODV-2,5 (cut-off voltage U<~1341.3 kV, pre-discharge time T<~12.5 ^s, the cut-off time TD<~5.47 ^s, the vertical scale is 268 kV/cell; the horizontal scale is 2.5 ^s/cell) [20]
2. Metrological support of testing of technical
objects for commutation stability. In order to conduct full-scale testing of power engineering facilities for commuttaion stability, a unique CVPG was created at the R&DPCI «Molniya» of the NTU «KhPI» at the experimental range of the Institute (Andreevka, Kharkiv
region) in 2012. The CVPG is rated for a voltage of ±2 MV [23]. This outdoor CVPG allows, in the field conditions, to reliably form, in accordance with the requirements of [5], a standard aperiodic commutation pulse of the time shape of 205 ^s/1900 ^s of both polarities in the field conditions on a large-sized electrical load under test.
To measure the ATPs of voltage pulses formed in the CVPG generator circuit, a superhigh-voltage ohmic voltage divider of the ODV-2,5 type described above can be used [20]. The data in Fig. 14 clearly illustrate the practical use of a superhigh-voltage ohmic voltage divider of the ODV-2,5 type at metrology support for testing the electrical strength of long air gaps in electric power devices for commutation stability. Fig. 16 shows the oscillogram of a full standard commutation pulse of time shape of 205 ^s/1900 ^s of positive polarity obtained in the discharge circuit of the CVPG generator in field conditions in the open air using an ohmic voltage divider of the ODV-2,5 type [23]. From the oscillogram of Fig. 16 it follows that the amplitude Umk of the commutation voltage wave in this case is approximately Umk ~ 9 V x x 53.65-103 ~ 483 kV. For the voltage commutation pulse formed on a long air gap, the rise duration Trise reaches a numerical value of about Trise~205 ^s. In this case, the duration of the commutation voltage pulse TP at the level of 0.5 Umk equals approximately 1900 ^s.
Fig. 16. Oscillogram of the full standard aperiodic commutation voltage pulse of positive polarity generated in the discharge circuit of the superhigh voltage generator of the CVPG on a two-electrode «needle-plane» system with an air gap length of
3 m and recorded with an ohmic voltage divider ODV-2,5 (Umk=483 kV; rise duration of the voltage pulse is Trise~205 ^s, duration of the voltage pulse is Tp= 1900 ^s, the vertical scale is 268 kV/cell, the horizontal scale is 500 ^s/cell) [23]
Conclusions.
1. Analysis of the current state of metrologicy support of full-scale testing of industrial power engineering objects, aircraft and rocket and space equipment on lightning resistibility and commutation stability in Ukraine shows that the R&DPCI «Molniya» of the NTU «KhPI» currently has not only high-voltage pulsed technology reproducing in this area required by the
requirements of domestic and foreign regulatory documents test pulses of current and voltage by powerful high-voltage electrical installations, placed outdoor and in heated special laboratory premises, but also the corresponding measurement means, passed state metrological calibration.
2. The composition of these high-voltage measuring instruments used in the practice of full-scale tests at testing the durability of energy facilities, aircraft and rocket and space equipment to affect their electrical equipment, components and components of lightning current (voltage) pulses and commutation voltage pulses include the following non-standardized devices of own manufacture: high-voltage high-current shunts of type SC-300M1 and SC-300M2, intended for measurement of micro- and millisecond pulses of a current of amplitudes up to ±220 kA with an integral of their action up to 15-106 J/Q; capacitive (CDV-100 and CDV-1,2 type) and ohmic (ODV-1,2 and ODV-2,5 type) dividers of pulsed voltage of micro- and millisecond duration, capable both of measuring with the help of metrologically attested DSO, and forming the standard (non-standard) lightning and commutation voltage pulses with amplitude up to ±2 MV on a tested certain electrical load with a capacitive characteristic.
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Received 19.07.2018
M.I. Baranov1, Doctor of Technical Science, Chief Researcher, S.G. Buriakovskyi1, Doctor of Technical Science, S.V. Rudakov2, Candidate of Technical Science, Associate Professor,
1 Scientific-&-Research Planning-&-Design Institute «Molniya», National Technical University «Kharkiv Polytechnic Institute», 47, Shevchenko Str., Kharkiv, 61013, Ukraine,
phone +380 57 7076841,
e-mail: baranovmi@kpi.kharkov.ua, sergbyr@i.ua
2 National University of Civil Protection of Ukraine, 94, Chernyshevska Str., Kharkiv, 61023, Ukraine, phone +380 57 7073438,
e-mail: serg_73@i.ua
How to cite this article:
Baranov M.I., Buriakovskyi S.G., Rudakov S.V. The metrology support in Ukraine of tests of objects of energy, aviation and space-rocket engineering on resistibility to action of pulses of current (voltage) of artificial lightning and commutation pulses of voltage. Electrical engineering & electromechanics, 2018, no.5, pp. 44-53. doi: 10.20998/2074-272X.2018.5.08.
