secondary bushings insulated for the high voltage of the necessitates removing any internal lead connecting the series  street  circuit,  a  special  booster  transformer  is two coils. The additional load handled by this device preferred  to  an  ordinary  distribution  transformer  for  use equals the product of the street-circuit current and the with  constant-current  regulators  of  10  kilowatts  and secondary  voltage  of  the  transformer.  Thus,  if  a larger. In using a booster transformer, the primary coil 2,400/240-volt transformer is used, the additional load Since transformers used for this purpose should have must   be   isolated   from   the   secondary   coil   that STRAIGHT-SERIES LAMPS WITH FILM CUTOUT CIRCUIT RATING IN AMPERES 6 . 6 15 2 0 REGULATOR 600 800 1,000 2,500 4,000 RATING 4,000 LUMENS    LUMENS 6,000 6,000 15,000 25,000 LUMENS 10,000 LUMENS (kW) LUMENS   LUMENS LUMENS   LUMENS   LUMENS   LUMENS   LUMENS 1 21 17 14 6 4 2 4 3 3 2 42 34 28 12 8 5 8 7 6 3 2 1 3 64 51 43 18 12 8 12 11 9 5 3 2 5 107 86 72 30 18 13 20 19 13 9 6 3 7.5 161 129 108 45 30 20 30 29 21 12 9 5 10 214 172 144 60 40 26 40 39 28 16 11 7 15 321 258 216 90 60 40 60 58 47 25 16 10 20 428 344 288 120 80 55 80 7 8 56 34 22 13 25 535 430 360 150 100 66 100 97 70 42 28 17 30 642 516 432 180 120 80 121 117 85 50 34 21 UNIT kW* .047 .058 .069 .167 .250 .375 .249 .256 .354 .600 .880 1.43 LAMPS  WITH  AUTO  TRANSFORMERS  AND  LAMPS  WITH  ISOLATION  TRANSFORMERS CIRCUIT  RATING  IN  AMPERES 15 20 6.6 15 20 REGULATOR 4,000 6,000 10,000 15,000 25,000 1,000 25,000 4,000 RATING LUMENS 6,000 LUMENS 10,000 15,000 25,000 LUMENS    LUMENS (kW) ^{LUMENS    LUMENS   LUMENS  LUMENS   LUMENS}LUMENS  LUMENS   LUMENS 1 3 2 1 1 0 12 5 3 2 1 1 0 2 7 5 3 2 1 24 10 7 5 3 2 1 3 11 7 4 3 2 32 15 10 7 4 3 2 5 18 13 8 5 3 53 25 17 12 7 5 3 7.5 27 19 12 8 5 80 38 26 18 7 5 10 37 11 26 16 11 6 107 51 35 25 15 10 6 15 55 39 24 16 10 160 76 52 37 23 15 10 20 74 52 32 22 12 215 102 70 50 30 20 12 25 92 65 40 27 16 268 127 87 62 38 25 16 30 110 78 48 32 20 322 152 104 74 46 30 20 UNIT  kW* .273 .384 .625 .935 1,500 .093 .197 .288 .405 .650 1.000 1.500 HIGH-INTENSITY   DISCHARGE   LAMPS LAMP CAPAFITY OF REGULATORS IS LIMITED BY STARTING CURRENT. DETERMINE UNIT kW BY MULTIPLYING LAMP WATTAGE BY  THE  FOLLOWING  FACTORS: 2.1  FOR  AMBIENT  TEMPERATURES  NOT  BELOW  +35°F  (+2°C) 2.5  FOR  AMBIENT  TEMPERATURES  TO  -30°F  (-34°C) THE  PROPER  SIZE  REGULATOR  TO  SELECT  IS  THE  SMALLEST  RATING  WHICH  EXCEEDS  THE  SUM  OF  THE  UNIT  kW  FOR  ALL LAMPS ON THE CIRCUIT, REGARDLESS OF TYPE. *UNIT  kW  IS  THE  APPROXIMATE  kW  CAPACITY  REQUIRED  FOR  A  SPECIFIC  LAMP  AND  ITS  ASSOCIATED  TRANSFORMER  OR BALLAST  AS  APPLICABLE. 06NP0273 Figure 6-21.—Approximate lamp capacity for street-lighting regulators. 6-20