Document BRXnpmVZd2dwwxdLV0venV30X

oSg ip PS: uOj Ol >- o C05 rZ- CQO= --OI OLlJOS OO3 5I OO oOH* oo=5: ooefc ccLj-< ea O >-*2o Lak.J CO I 2Sk ^o o Q= Z P I'I fgcSr< oo 0>0< O UJ Q= O O LU U. c J-- u O ! < =d 274 MOTOR and WIRE RATING DATA Control Circuit Transformer Selection A control circuit transformer will not overheat when operated at its maximum continuous volt-ampere (VA) rating, nor will its secondary output voltage fall below 95% of rated output voltage when selected according to the following recommendations: (A) The continuous VA capacity of the transformer should be equal to or greater than any continuous maximum VA requirement of the controller. (B) The inrush VA capacity of the transformer should be equal to or greater than maximum VA inrush which can occur for any combination of sealed and inrush VA requirements of the controller. The VA values which fulfill these requirements may be readily calculated: (A) The continuous sealed VA requirement is found by combining with the aid of the chart on page 275 the total sealed WATTS with the total sealed VAR. These two totals may be obtained from the Component VA Table. Tentatively choose a transformer with a VA or (KVA) rating equal to or greater than this value. (B) The maximum VA inrush is similarly found by combining the maximum inrush WATTS which can occur with the corresponding maximum inrush VAR again with the aid of the chart on Page 275 and the Table. It may be necessary to use inrush values for all devices or a combination of inrush and sealed values depending upon what condition produces the maximum VA inrush for the specific controller. The Percent Load Power Factor is found as follows: ___ , Maximum Inrush WATTS .... %PF----------------------------------- XlOO Maximum Inrush VA This maximum VA inrush at the calculated PF must be less than the value allowable on the inrush curve for the transformer selected according to (A). Example: Assume that in a given circuit one size 1 starter, one type BG relay, and one type PT timer are energized. After an interval of time, one type DM, 2 N.O. relay and one size 5 starter are energized. ' Select the transformer as follows: A) Continuous VA requirement: Device 1 Size 1 starter sealed................. ............................ 1 Type BG relay sealed............................................. 1 Type PT--on delay timer sealed.................... ..... 1 Type DM relay sealed.......................................... 1 Size 5 starter sealed...................... VAR 43 4Q 25 ... 120 Watts 16 14 8 (Latched) 50 (B) Maximum VA inrush requirements: Device 1 Size 1 starter sealed................................. .......... 1 Type BG relay sealed.................. 1 Type PT--on delay timer sealed............... .......... 1 Type DM relay Inrush........ ...................... ............ 1 Size 5 starter inrush................................ .......... VAR 43 40 25 210 1894 Watts 16 14 8 255 360 TOTAL SEALED 228 (VAR) From Chart (Nomograph) Total Sealed VA - 243. Tentatively select a .25KVA transformer. 88 (Watts) TOTAL MAXIMUM INRUSH 2212 (VAR) From Chart (Nomograph) Total Max. Inrush VA - 2300. Percent Load Power Factor: PF in % Max. Inrush Watts x 100 = 653 x 100 . Max. Inrush VA 2300 28.4% The inrush (selection) curve for the .25 KVA transformer shows that 2300 VA at 28% power factor is higher than the inrush availability. Therefore, the secondary voltage woujd drop below 95% (NEMA STD.) with this inrush, and the next larger, or .35 KVA transformer must be selected. 653 (Watts) COMPONENT VA TABLE Relays Component Inrush VAR Watts VA Type AA .......................................... 18 8 20 Type BG and BC ............................... 102 21 105 Type CF .......................................... 42 15 45 Type CF with latch ........................... 10 9 15 Type BJ .......................................... Type AF .......................................... 8 8 6 IQ 6 10 Type DM - 1 N.O. or 1 N.O. and 1 N.C. 73 98 122 -- All others....................... 210 255 330 Sealed VAR Watts VA 8 7 10 40 14 42 14 3 14 446 5 68 5 68 ... ~ -- ... ... - Type ET .......................................... Type MX..................................... Type RS .............................. Type TF ....................................... Type TH .......................................... ... 18 3 4 4 ... 8 20 4-- 34 45 ... 8 3 4 4 7 10 4 ... 34 45 Component Timers Type SP -- Motor.............................. -- Solenoid.......................... Type PT -- AD and AE....................... -- BD off Delay .................... -- BE on Delay..................... inrush VAR Watts 33 57 50 97 94 74 64 87 88 VA 4 76 135 98 124 Sealed VAR Watts 33 13 2 19 7 24 8 25 8 VA 4 13 20 25 26 Contactors and Starters Size 0........ .................................. 102 24 105 40 14 42 Size 1 .............................................. 151 33 154 43 16 46 Size 2.............................................. 532 136 550 83 21 86 Size 3.............................................. 844 150 900 86 24 110 Size 4.............................................. 946 164 960 83 26 87 Size 5.............................................. 1894 360 1925 120 50 132 CUTLER.HAMMER- 274