354 BIBLIOGRAPHY MODERN POWER TRANSFORMER PRACTICE Bolton, D. J., Electrical Engineering Economics, Chapman and Hall, London, 2nd edn (1936) Brownsey, C. M., 'The Problem of Noise with Particular Reference to Transformers', Mem, No. 3, Central Electricity Research Laboratories (1956) Franklin, E. B., 'Distribution of Water in Transformer Insulation', Electr. Times, 147, 787 and 839 (1965) Ellis, R. M., Transformer Vibration Isolation Materials Central Electricity Research Laboratories (Leatherhead) Report No. RD/1/Rl5ll (1968) Norris, E. T., 'Loading ofpower Transformers', Proc. Inst. Electr. Eng., 114,428 (1967) Sealey, W. C., Paralleling Load-tap-changing Transformers, Allis Chalmers Rev., third quarter (1954) British Electricity Supply Regulations, British Electricity Supply Industry, H.M.S.O., London (1937) Guide to Transformer Noise Measurement, BEAMA Ltd Pub. No. 227, (1968)
Index Ampere-turns balance 3, 117 residual, effect on force 136 Breather, dehydrating 219, 282-3 Buchholz relay (see gas- and pressureactivated protective relay) Bushings, high-voltage 285-8 Conservator (see oil-expansion vessel) Cooling 7 arrangement, classification 10 of buried transformers 300-3 of distribution transformers 217 ducts in transformer core 107 enclosure effect on air-cooled transformers 339-45 firm supply to group of distribution transformers 326 of gas-insulated transformers with class A insulation 312-13 of generator transformers 274--5 medium 7 oil flow in disk winding 130-3 rating increase by adding air-blast fans 278 temperature distribution in ONAN transformer 24--7 oftransmission transformers 275-7 Cost of transformer 37 capitalisation 38 at change of distribution type 332-5 economic aspects of distribution type selection at pre-specification stage 327-39 economic considerations in distribution type design 210-11 optimisation 80 Costing of distribution transformer losses 327-32, 336-7 Electric screens in high-voltage winding 124-5 Electromagnetic forces on series-inductor winding 266-7 on transformer winding 134--7 Gas- and pressure-actuated protective relay (Buchholz) 219, 283 Impedance limit on maximum number of parallel transformers 319-21 percentage 8 voltage 7, 10 zero-sequence, measurement 173-4 Induction electromagnetic 1 mutual 1 self- 1
356 INDEX Inductor, power system 260--71 cast-in-concrete type 267~9 insulation level of shunt type 264 noise of forced-cooling plant 263-4 noise of gapped-core type 261 oil-immersed type 269~71 series type 264-71 shunt type 260--4 Insulation ageing 7 classification 295~6 of conductors 114 of core laminations 85~9, 97~8 in distribution transformers, highto low-voltage 216 electric strength in air-space transformer 296-7 gas type 113 level of shunt inductors 265 level of transformers (see voltage testing of transformers) liquid type 113 moisture content 156 resistance, measurement 181~2 solid type 113 ofwinding 22-4, 113~15 Losses capitalisation 336-7 classification 6 consideration in transformer design 18~22 costing for distribution transformers 327~32, 336-7 in shunt inductors 264 in transformer core 102~3 in transformer tank 129~30 in transformer winding 127~9 Magnetising current 3, 104 harmonic content 271~3 circulation pumps 277~8 dehydration breather 282 Drycol automatic dryer 282~3 effect of temperature 282 expansion vessels (conservators) 219, 282-4 maintenance 219, 284~5 monitoring of gas content 12 preservation of insulation property 280--5 properties required 113 protection 283-4 temper;ature calculation 132~3, 238-42 testing 182 Paralleling of distribution transformers choice of inherent impedance 320--1 limit of maximum number 319~21 mode of operation 321~2 Reactance 5 of distribution transformers 211 of generator transformers 245~6 percentage 8 significance 28~ 30 voltage 7 Resistance of cold winding, final test measurement 168 of cold winding, preliminary test measurement 155 of hot winding, measurement 181 of insulation, measurement 181~2 percentage 8, 22 voltage 7, 22 Short-circuit requirements 134~7, 242~3, 266, 314 Oil Site assembly of transformers 292~3 circulation path in windings 131 ~2 Specification for a transformer
customer's 62 designer's 63, 210 of example of calculated design 50, 221 of example of computer-aided calculation 70 of noise level 195-9 of noise measurement 194-5 standard (selection) 12-16 Tank 10 calculated design example 240-2 of coal-mine transformers 305-6 configuration 26 design 57-60 of distribution transformers 217 effect on noise 190 losses 129-30 of system transformers and inductors 278-80 Tap changer, on-load 139-52 basic design considerations 141 diverter switch 141, 145, 150 double-resistor type 145-6 inductor switching type 149-50 maintenance 152 motor drive 151 protection 151-2 single-resistor type 146----49 tap selector 141, 143, 145, 150 type test 142 Temperature calculated example for distribution transformer 235-42 distribution in ONAN transformer 24-5 distribution in transformer core 107 effects of enclosure around aircooled transformers 339-45 gradient in winding 26-7 hot-spot, in dry-type transformer winding 296 hot-spot, in oil-immersed transformer winding 25, 281 INDEX 357 hot-spot, in transformer core 107 measurement in winding by resistance 133-4 reference, related to insulation class 173 rise in core 104-7 rise in disk winding, calculation 132-3 rise in oil, testing 180 rise in winding, testing 174-9 specified rise limits 26 Transformer auto- 3, 249-54 buried type 300-4 classification 1 coal-mine type 304-6 distribution type 1, 209-43, 318-54 dry type 295-300 dual-low-voltage type 257-8 earthing type 258-60 equivalent circuit 4-5 fault protection 346-7 faults 345-6 fittings of distribution type 218-19 forming purchase decision at prespecification stage 318-27 gas-filled type 113-14 gas-insulated type in class A 311-14 generator type 245-8 ground-mounted distribution type 219 idealised 3 life expectation 281-82 liquid-immersed type 113 loading of distribution type 324-7 main parts 9-11 maintenance 12, 347 oil-expansion vessel (conservator) 219, 282-4 optimum rating of distribution type 323-4 pole-mounted distribution type 218 power system type 1, 244-60, 271-94 processing 155-9
358 INDEX Transformer (contd.) quadrature booster 254-6 rectifier type 314-17 site assembly 11, 292-3 temperature distribution in ONAN type 24-6 terminal arrangements in distribution type 218 transmission type 248-60 transportation 11, 288-92 two-winding type 2, 256-8 USA practice of distribution type 220 welding type 306-11 T ran sf ormer cores 84-111 building factor 103 calculation of internal temperature 107 construction for distribution type 211-13 cooling ducts 107 cross section 89-92 frame dimensions, calculated example 50--6 frame dimensions, estimation 41-50 frame selection 32-6 hot spot 107 joints 94-6 lamination insulation 85-9, 97-8 lamination preparation 96-7 lamination stacking and clamping 98-102 losses 102-3 magnetostrictive vibration 107-9, 188-90 pattern 92-3 steel used 84-5 temperature rise 104-7 Transformer design copper loss, consideration 19-21 customer's specification 62 designer's specification 63 dimensions of core frame, calculated example 50--6 dimensions of core frame, estimation 41-50 efficiency and cost, consideration 36-8 electronic computer aid 61-83 example calculated for distribution type 221-43 general procedure 8 iron loss, consideration 18-19 practical constraints 27-32 principles (theoretical) 18--60 selection of core frame 32-6, 222 standard specifications (selection) 12-16 tank 57-60, 217 winding 56-7, 121-7 Transformer noise 11, 187-208, 327 effect of cooling fans 193--4 effect of core clamping 107-9 effect of core material 109 effect of tank 190 effect of transformer support 190 noise level anticipation in planning 202-3 noise level of distribution type 242-3 noise level measurement 194-9 noise level reduction measures 195, 200-2 noise level specifications 195-9 source 188 Transformer testing 11, 153-5, 159-86 of accessories 182 of buried type 304 example recorded with a large transformer 183-5 final stage 159-83 with induced over-voltage 165 for internal discharge 167-8 of oil 182 preliminary stage 153-5 with separate-source voltage 164-5 on site for commissioning 182-3 with surge voltage 159-64 Transformer windings 112-37 arrangement 22--4, 120--1 clamp design 137
common types 116-20 conductor material 113 construction for distribution type 213-17 cooling 130-3 design 56-7, 223-9 design economics 137 design requirements 112 design for test at power-frequency voltage 121-2 design for test with surge voltage 122-7 disk type 117-18, 125-7 double-concentric 245 electric screen 124--5 foil, in distribution type 216-17 forces (mechanical) 134--7 formation 69, 225-9 helical type 39, 116, 124 high-voltage, in distribution type 214--15 hot spot 25 INDEX 359 to improve oil circulation 131-3 insulation 113-15 interleaved disk 127 losses 127-9 low-voltage, in distribution type 214 multi-layer high-voltage 116 space factors 38~1 stabilisation type 271-3 surge-voltage distribution 124 tapping location m autotransformers 250 tapping in distribution transformers 215-16 tappings 119-20, 142~ transposition of multi-strip conductors 114, 231-2 Transportation 288-92 Turns ratio 3 change 3 Units of measurement 16-17