Document yrg265Oq9vNmDNYEVKB6p42YD

PYRALENE GENERAL OBSERVATIONS ON THE " PYRALENE" LIQUID DIELECTRICS (Trade-Mark) This pamphlet is destined for engineers and manufacturers who wish to hava a quick comprehen sive review of the properties and main applications of Pyrolene. For any well known application refer to the special pamphlet. For any application not mentioned In our pamphlet, It will be advisable to consult our Technical Department which in collaboration with our laboratories is al the disposal of alt parsons interested in Pyrolene. I -- GENERAL l.l -- ORIGIN OF PYRALENE Since 1934, French manufacturing companies have been studying the production and use of synthetic didcctncs. This research made it possible in 1941 to meet a shortage of mineral oil, and over one thousand five hundred transformers were immersed In these synthetic dielectrics. These dielectrics, known under the names : Dleledrol. Chloranol. Afeoilne, were substitute products, and in 1946 they were discontinued. Experience gained with these dielectrics was not wasted for In 1947 it was found posslbla to manufacture succesfully entirely different chemical products, their physical and alactrlcal charocte nstlcs. Comply with the recognised International characteristics which describe " Askarets **. HONS 07201** P. 10 -- 2 1.2 -- DIELECTRIC LIQUIDS 1.2.1. - Mineral oil : Up lo ihc last few years, mineral oil was the liquid dielectric most currently used by the elec* trical industry. Mineral oil has good Insulating characteristics but it also Has a serious draw back, which is the mam reason for making Its use difficult : mineral oil tends to oxidise* oxidation of the oil gives rapidly rise to : ' -- sludge formation; -- increase in viscosity, acidity and hygroscoplclty; -- decrease of its dielectric strength and Insulating resistance. Furthermore, mineral oil. when subjected to intense electrical fields undergoes a chemical change which is well known as " Wax X " formation. Moreover, mineral oil being a hydro carbon ignites when decomposed by heat or by an electric arc. The products evolved by decompositions include hydrogen which reads violently with oxygen of the air, and this reaction is followed by an explosion and fire. 1.2.2. -- Non-inflammable dielectric liquid : To eliminate all danger of fire, a dielectric liquid which is decomposed by heat or by on eledrlc arc must not evolve any free hydrogen, furthermore, gases evolved by decomposition must be stable even at a temperature which is higher than that which caused the decomposition: this Is the definition of dielectrics belonging to the ASKAREL " class. Hydrogen chloride evolved by combining chlorine and hydrogen is a gas which answers this requirement. Since an atom of chlorine is necessary to saturate an hydrogen atom, the chlorinated dieledric must contain nt least as many chlorine as hydrogen atoms. 1.3 -- NATURE OF PYRALENE : 1.3.1. -- Formula : They are essentially chlorinated derivatives of benzene type molecules. Diphenyl which is the result of the link of two benzene molecules Is the basie element in the manufacture of chlorinated dielectrics. In its formula Ci: Hu> at least 5 cnlorme atoms must be substituted to comply with non inflammability conditions. MCNS 072015 PHYSICAL AND CHEMICAL, CHARACTERISTICS OF PYRALENE (Average values) REFERENCE PTRALENE 1499 PTRALENE M?6 PTSAlENE M.-'i PYRALENE 1422 PYRAlcNt 1477 PtPalENE I4>7 Pi F Al ENt H.'3 Appearance ........................... Pour point in :C...................... Viscosity in csl.......................... Specific gravity at 100 C......... at 20 C......... Coefficient of expansion .... Specific heat in cal/'g/cC (20-100)................................... Conductivity heat at dear, almost colourless liquid -- 18 8 at 55C 1.31 1 38 0.00068 0.28 clear, almost colourless liquid --9 54 at 80-C 1.33 1.46 0.000685 deer, clmcst colourless liquid + 10 6.5 al 100 C 1.47 1.55 0.000689 0.27 0.26 clear, almost colourless liquid + 30 14 at I00=C 1.44 1.63 0.00075 0.25 clear, almost colourless liquid -- 45 2.B at 55:C 1.41 1.49 0.00075 0.27 clear, aim .,st colourless liquid -- 32 2.5 at B0C 1.48 1.56 0.00073 0.26 clear, cimosl colourless liquid -- 45 1.9 at 80 C 1.46 1.54 0.00070 0.26 40 C r ........................ mh 'C 0.095 0.091 0.087 0.083 0.091 0.083 0.083 Refractive Index at 25 C.... 1.624 1.630 1.637 1.646 1.604 1.615 1.608 Evaporation losses.................. 0.12 0.07 0.03 0.01 3 2.5 3 (2hrs at I25'C) (2hrs at !25cC) (2hrs at I25"Q (2hrs at I25C) (6hrs at 100'C) (6hrs at I00C) 6hrs at I50C) Flash point ............................. nil nil nil nil nil nil nil Acidity (mg KOH/g).............. 0.01 max. 0.01 max. 0.01 max. 0.01 max. 0.01 max. 0.01 max. 0.01 max. Chlorine ion per cent .......... I0-4 max. I0-3 max. IO-` max. I0-3 max. I0-3 max. 5.I0-4 max. 5.I0-4 max. Dielectric constant at 100 C (50 lo 1.000 c/s) ................ 4.8 4.6 4.2 3.8 4.2 4 4 Tangente of the loss angle at 100 *C (50 c/s) .................. 0.04, max. 0.03 max. 0.015 max. 0.01 max. 0.04 max. 0.03 max. 0.03 max. Resistivity at 100 *C after 1 min. under 200 V/mm. in Q cm/cm* ............................ 1 x I0>* min. 1 x I01: min. 1 x 10** min. 1 x lO13 min. 0.6 x I01* min. 1 x I011 min. 1 x I013 min. Dielectric strength in kV/cm (ASTM).................................. 200 min. 200 min. 200 min. 200 min. 200 min. 200 min. 200 min. Applications ............................ capacitors capacitors capacitors cablescoplasticisers capacitors transformers transformers p. M HONS 0 7 2 0 1 6 P. 10 - 4 ! .3.2. -- Adapting the Pyrolene for use : -- by varying the rate of chlorination of the diphenyl; -- by mixing two or more Pyrolenes. It is possible to obtain quite a range of Pyralene which will comply with Ihe requirement! of the electrical Industry : viscosity, setting point, loss by evaporation, etc... Moreover, these products undergo special 'purification to give them the dielectric cheraderistics essential for the Insulation of electrical apparatus. In short, ihe chemical industry has made synthetic dielectric liquids available for the electrical Industry. -- non-inflammable, having no explosive vapours; -- stable, i.e. non oxidlsable and non ageing; -- perfectly adapted for use -- excellent insulators. 2 - DIFFERENT TYPES OF PYRALENE There are three distinct types of Pyralene having characteristics which are adopted to Hit three main applications: -- for transformers; PYRALENE 1467 and 1470; -- for capacitors; PYRALENE 1476, 1498. 1499 and 1477; -- for various applications : (plasticisers) : PYRALENE 1462 and 1476. 3 -- GENERAL PROPERTIES OF PYRALENE The characteristics of Pyralene and their incidence on the design of electrical equipment ore reviewed in our pamphlets outlining their applications. 3.1. -- PHYSICAL PROPERTIES : Pyrolenes are coiouriess liquids. Their specific gravity Is higher than that of mineral oils. It varies from 1,38 to, l,S6 at I00*C. "ONS 07i017 *. 10 - s Their viscosity varies from 0,5 to 14 cst. at lOO'C. Their pour point lies between -- 50''C and 30"C. Their ipccific heat is characteristic of a good cooling liquid. Their vapour pressure remains always low, even at temperatures exceeding I20*C. Their losses by evaporation are negligible. Their non-inflammability is guaranteed. (Official report on tests made by the Conservatoire des Arls et Mitiers). 3.2 -- CHEMICAL PROPERTIES : Pyrolene are : -- completely neutral (acidity less than 0,01 mg KOH per gram of Pyralene); -- stable, and without any tendency to form sludge ; -- slightly hygroscopic, they can dissolve a maximum of 100 ports water per million et 20*C. Com mcrcially the water content of Pyralene is less than 30 parts per million, -- hove no action on commonly used metals : copper, aluminium, iron, bronze, tin, etc. Pyralene dissolves a certain number of materials used In the construction of electrical equip ment. Compatibility tests have been systematically carried out'by our laboratories and by those of the electrical industry, results obtained guarantee the choice of materials : solid Insulators, varnishes, resins. lacquers, gaskets, etc. Under the influence of on electric ore, Pyralene is decomposed into a certain number of gases, mainly hydrochloric acid (98 per cent). No toxic gases, free chlorine or photgano are found by analysis (tests by official laboratories). 3.3 -- ELECTRICAL PROPERTIES 3.3.1. -- Dielectric constant ond dielectric lossas : Pyralene, polar liquids, are characterised by : -- high dielectric constant (approximately 5 as against 2,5 for mineral oil); -- low dielectric losses, slightly higher, owing to their polarity, than with new mineral oil. 3.3 2. -- Dielectric strenght : The dielectric strength of Pyralene is very high, currently, reaching 200 kV/cm measured with an A.S.T.M. spark-gap (space between discs 2;5 mm). HONS 072018 P. 10 -- 6 3.3.3. -- Direct current resistivity : At I00"C under 500 V with 2,5 mm spaced electrodes, the resistance of Pyrolene is about 10` - 11, cm/cm1. 3.3 4 -- Factors influencing the electrical properties : All the electrical properties of Pyrolene, substances of a resinous structure, are governed by the rule of polarity as shown by Debye in his theory of permanent dipoles. The polar properties of Pyralene explain their behaviour in relation to heat and the frequency to which they are submitted. a) influence of temperature (fig. I). Generally, an increase in temperature brings about an increase In losses and a decrease of the dielectric constant and resistivity. Losses, in this case, are usually due to conductivity. The curve of the tangent of the loss angle (tang. ) in relation to temperature, when hot. is a curve which is vary close to that of the fluidity of the liquid. These losses are, in effect, caused by vary small quan tities of tonisablc impurities which might have been dissolved in the liquid, and tha mobility of tha ions is reduced by the viscosity of the liquid. As by heating the fluidity is increased tha losses increase more or less m the same ratio. Earth treatments reduce these losses. If, on the contrary. Pyralene 1476 Is cooled to complete solidification, a sharp increase In losses and a rapid decrease in the dielectric constant in the region of the solidifying point will be noticed then the losses revert to normal and the dielectric constant tends towards its optical value (square of the refractive index). These losses are due to the hindrance of the orientation of the dipoles in tha alternating field by the viscosity. This phenomenon, known as anomalous dispersion, occurs also with the other Pyralenas, but at much lower temperatures. (Lower than -- 50cC for Pyralene 1477). b) influence of frequency : (fig. 2). Low viscosity Pyralene is practically unaffected by the frequency of the current, when cold, and in the low frequency field. However, losses, when hot, undergo a variation which Is approxima tely Inverse to frequency : for instance, passing from a frequency of 50 c/s to 500 c/s divides tha lossos, when hot, by a factor of approximately 10. Imparities act as a shunt resistance In the liquid capa citor. Pyralene 1476 on the other hand shows a maximum of losses for a given frequency and tamparature. This maximum corresponds to that of the anomalous dispersion. The higher the tempera ture, the higher the frequency at which the dispersion occurs. These losses are of a molecular nature and earth treatment has no effect on them. The dielectric constant also drops sharply and tends towards its optical value. HONS 072019 r. 10 -- 7 Comparison between the variation of tg 8 and the variation of fluidity versus temperature for chlorinated liquid* of various viscosities. ') High viicoiity liquid (9) Medium vltcoaily liquid (3) I nw ylitiwHr llgeld Flf. I MOMS 072020 P. 10 -- 8 c) Influence of impurities ' Acidity, alkamty or the presence of foreign substances in suspension decreases Hit dielectric quality of Pyralcnes. An increase of losses is noticed. As Pyralene has a high dielectric constant and the Ionizing power of the solvents increase approximately in an exponential manner in relation to tho dielectric constant, relatively small quantities of dissolved impurities give the liquid high losses. Hcncc Pyralencs must be carefully manipulated, they should not be used in the presence of materials which might contaminate them. Note that contaminated Pyralenes can retain a very high dielectric strength (over 200 kV/cm) whilst also having high dielectric losses (0.3). J) Influence of humidify : Absorption of moisture decreases the dielectric strength of Pyrolene; however, this drop of a,electric strength, for the same quantity of water absorbed is much lower than in the case of new mineral oil; besides an oil that has been used shows an increase in its capacity to absorb moisture which causes a still more rapid decrease of the dielectric strength. 3.4 _ PHYSIOLOGICAL EFFECTS ; Under normal conditions of use, Pyralenes can be handled without risk of toxic effects. The user is particularly recommended : -- to provide ventilation when opening up the impregnating autoclaves or to allow them to cool down to 50-60 ' C so as to avoid releasing too large a volume of vapours which art unpleasant to inhale an can have an irritating effect on the mucous membranes. -- avoid spilling hot Pyralene on the skin, which might cause some irritation. This irritation disap pears by washing with soap or rubbing with glycerine. 4 -- INDUSTRIAL USES OF PYRALENE 4.1 __ TRANSFORMERS The use of Pyralene in transformers gives the following advantages : -- safety -- economy. MGNS 072021 fc It -- SAFETY : Pyrolene is non inflammable and its vapours are non explosive. It is recommended for transformers, used in mines, buildings, theatres, under-ground Instal lations, underground railways, snips, locomotives and in all cases where the least risk of fire can be tolerated. ECONOMY : Such safety means an economy of space, materials, cost, erection time and operating cost. Economy of space : Use can be made of waste place (underground underroof, etc.) to house Pyrolene transformers. Economy of materials and erection time : Pyrolene does away with ontl-Are enclosures or concrete vaults which are essential in the casa of oil transformers. Fire equipment and an oil draining lank are also no longer required. Fmaily Pyraicne transformers are indispensable auxiliaries for power distribution throughout work-shops and arc systematically replacing distribution via a single sub-stotlon. Comparison, for equal power, between a central station (enclosure with on oil transformer) and four stations which are spread out (pre-fabricated stations with Pyrolene transformers), designed for distributing 2.500 kVA at i5 kV per work-shop having a length of 2*45 yards and 130 yards width, gave the following comparison : -- fur the centra/ sub-s/afjon : 2.500 kVA oil transformer : price 100 per cent; -- fo, 4 transformer stations : with Pyralene transformers each rated at 630 kVA : price 82 per cent. It must not be forgotten that because it Is possible to erect Pyralene transformers at the load centre, tl is also possible to effect a large economy in low voltage cables and in their Installation, their cost, per yard installed, for a load of 1.000 kVA varying as follows : -- A 380 V ; 100 per cent. -- B 15.000 V : 13 per cent. Bearing m mind the saving of time required for erection the total economy realised can In certain cases reach 40 per cent. Economy of power : having high voltage at the load centre leads to a large aconeny of cabla leakage. Moreover, the voltage drop in low voltage cables Is greatly reduced : It U well known that the torque of an asynchronous motor varies as the square of the voltage and that certain types of electric equipment require, to ensure correct operation and an acceptable valve life, a voltage having less than 5 per cent variations. Economy in maintenance : Maintenance of Pyralene transformers is practically nil; Pyralene docs not require any of the periodical treatments as does mineral oil. MOMS Q71Q22 P. 10 - 10 Very important : The advantages of Pyralene transformers have been recognised In France by Fire Insurance Companies who, by their notifications N" 573 and 574, considerably reduce Insurance premiums of electrical Installations equipped with transformers immersed In Pyralene. 4.2 -- CAPACITORS 4.2.1. -- The high dielectric constant of Pyrolenan twice that of oil glvae : -- increase in capacity : For equal volumes, the increase In capacity of a copadlor Impregnated with Pyrulcnc against one impregnated with oil Is approximately 40 per cent. For a given capacity, the use of Pyralene yields therefore an important economy of aluminium, paper and labour which can amount to approximately 20 per cent. -- a better distribution of the electrostatic field between the electrodes : The voltoge gradient to which each of two insulators in series Is subjected Is inversely proportional to the respective dielectric constants of each of the two insulators. in the paper-p/ralene complex, the liquid insulator will be under lower voltage stress than tha liquid in the paper-oil complex. With a voltage gradient of 15 V per micron applied to tha impregnated paper dielectric, the voltage stress resulting In Pyrolen* will only be 20 V per micron, as against 26 V per micron for oil. 4.2.2. -- High dielectric strength : Because this is clearly higher than that of mineral oil. It allows an Increase In the voltage gra dient employed : this can be 1,5 times more than in the case of mineral oil capacitors, taking Into account an equal safety factor. In fact, m most applications, an increase in the safety factor will be preferred, and thereby the life of the Pyralene impregnated capacitor will be lengthened. 4.2.3. -- Chemical stability : Pyralene is insensitive to the action of intense electrical fields which do not therefore give rise to any polymerisation. Mineral oil, on ihe contrary, by polymerisation gives rise to the formation of a wax, callad Wax X " which may lead to rapid deterioration of the capacitor by decreasing considerably Its Ioni sation voltage. 4.2.4. -- Non-inflammability : 4.2.5. -- The advantages of Pyralene capacitors, viz : -- small bulk; -- low losses; -- high stability; -- non-inflammability; ' MGNS 072023 * a loud lo itws (iirk'Unc being used for many different types of capacitors : to impiovt! Ihc (lower factor, low and high voltogc (units up to 100 kVAR); rci|><iuk>r\ for fluorescent tubes; -- capacitors for radio transmitters, radar delay cables, shock generators; -- coupling capacitors, voltage dividers, (high voltage cables); -- medium frequency capacitors for Induction furnaces, etc. Pyrolene impregnated capacitors comply with the official specification. r. io--H 4.3. -- CABLES Pyrolene H76 and 1482 make, on the other hand, excellent co*plasticlsers of polyvinyl chloride insulated cables . Pyralene gives ; -- a better resistance lo fire, -- greatly improved insulating proporftes (electrical resistance) which are usually greatly detracted when adding other plasticisers. (See our pamphlet P-35). 4.4 -- OTHER APPLICATIONS Pyralene arc also used as liquid dielectrics for : -- Selenium rectifiers; -- Instrument transformers; . -- Voltage regulators; -- Induction coils; -- Rheostats; -- etc. Let us also mention their use as heating liquids (pyrolenes 1498 and 1476) up to 2B0*C. HONS 072024 p. 10 - n KINEMATIC . VISCOSITY OF PYRALENE VS. TEMPERATURE TfMdMATUM -C MONS 072025 JL PYRALENE POUR CONDENSATEURS P. !- 13 1000 aO 70 BO 90 IOO 120 140 140 190 200 220 2*0 300 )40 TEMPERATURE c HONS 072026 i VAPOR PRESSURE OF PYRALENE VS. TEMPERATURE P. 10 - I) A TEMPCRATURI 'C MCNS 072027 P. 10 -- M VAPOR PRESSURE OF PYRALENE VS. TEMPERATURE OF Hg Va p o r PRESSURE i n HONS GJ2028 PYRALENE 1499 Dielectric constant and losses vs. Temperature 0 Frequency 50 Hz (g o.o?$ 0.020 0.01$ 0.010 PYRALENE 1498 Dielectric constant and losses vs. Temperature | fc. Frequency 50 Hz g ' , TEMPERATURE < TEMPERATURE 'C PYRALENE 1476 Dielectric constant vs. temperature 0 at various frequencies HONS 0 7 2 0 2 9 PYRALENE 1476 Dielectric losses tg 8 vs. temperature tg* at various frequencies f\i0,70 30 Mi 1000 _ 10000 V\/\30000 JA11M'IW\0.13 0,10 HONS 0 7 2 0 3 0 003 23 0 i i so m _ 23 N rtttpaumaf < 7i