MOTOR PROTECTION TABLES - Circuit Protection, …

1 2014 Littelfuse POWR-GARD ProductsMotor PROTECTION GuideUsing AC MOTOR PROTECTION TABLES to Select Fuse Ratings Time-delay RK1 and RK5 fuse ratings selected in accordance with the following recommendations also meet NEC requirements for MOTOR Branch Circuit and Short- Circuit Fuses for MOTOR Running PROTECTION Based on MOTOR Horsepower MOTOR horsepower and MOTOR Full Load Amperes (FLA) shown are taken from NEC TABLES through covering standard speed AC motors with normal torque characteristics. Fuse ratings for motors with special characteristics may need to vary from given MOTOR running PROTECTION will be provided by the fuses, select fuse ratings for correct type of MOTOR from MOTOR PROTECTION table Columns headed, Without Overload Relays.

2 If overload relays will provide principal MOTOR running PROTECTION , select fuse ratings for correct type of MOTOR from MOTOR PROTECTION table Columns headed, Back-up Running PROTECTION or With Overload Relays. Fuse ratings selected from these columns coordinate with most UL Class 10 and 20 overload relays which covers over 90% of MOTOR Fuses for MOTOR Running PROTECTION Based on MOTOR Actual Full Load Currents Better PROTECTION is achieved when fuse ratings are based on MOTOR actual FLA obtained from MOTOR nameplates. Locate MOTOR nameplate FLA in the column appropriate for the type of MOTOR and type of PROTECTION required. Then select the corresponding ampere rating of the fuse from the first column of that PROTECTION TABLESTIME DEL AY UL CL ASS RK1 OR RK5 FUSE AMPERE R ATINGMOTOR RUNNING PROTECTION (USED WITHOUT PROPERLY SIZED OVERLOAD RELAYS) MOTOR FULL-LOAD AMPSBACK-UP MOTOR RUNNING PROTEC TION (USED WITH PROPERLY SIZED OVERLOAD REL AYS) MOTOR FULL-LOAD AMPSMOTOR SERVICE FAC TOR OF OR GRE ATER OR WITH TEMP.

3 RISE NOT OVER 4 0 SERVICE FACTOR LESS THAN OR WITH TEMP. RISE GRE ATER THAN 40 SERVICE FAC TOR OF OR GRE ATER OR WITH TEMP. RISE NOT OVER 4 0 SERVICE FACTOR LESS THAN OR WITH TEMP. RISE GRE ATER THAN 40 C 1 1 - - 15 - 2 - - - 1 4 1 6 8 11 11 0 14 11 0 18 4 0 5 8 21 0 6 6 21 32 31 0 - 56 61 71 86 . 4 0 97. 2 0 -7. 9 . 41-7. 2 3 0 4 4 171 0 915 . 2 2-17. 3 - 4 0 -2 0 . 0 . 2 2-17. 3 9 4 0 -2 . 0 0 -2 7. 9 0 4 .7 9 - 3 0 . 4 4 - 3 8 - 4 9 - 3 9 .13 - 4 6 - 6 7 806 0 3 -17 5.

4 6 5 -2 17. 3 17. 4 0 -2 6 0 . 8 7 4 7. 8 3 - 3 9 1. 2 - 4 3 4 7. 8 4 - 3 9 1. 3 0 4 3 of Class RK5 Fuses (FLNR_ID / FLSR_ID / IDSR Series) or POWR-PRO Class RK1 Fuses (LLNRK / LLSRK / LLSRK_ID Series) Based on MOTOR Full Load AmpsMotor PROTECTION White PaperDownload our white paper on MOTOR PROTECTION at 2014 Littelfuse POWR-GARD ProductsMotor PROTECTION GuideMOTOR PROTECTION TABLESMOTOR HPFULL LOAD AMPSWITHOUT OVERLOAD REL AYSWITH OVERLOAD REL AYSSWITCH OR FUSE CLIP R = OR MORE, TEMP RISE NOT OVER 4 0 = LESS THAN OR TEMP RISE MORE THAN 40 = OR MORE, TEMP RISE NOT OVER 4 0 = LESS THAN OR TEMP RISE MORE THAN 40 C460 VOLT 3-PHASE MOTORS (480V Circuit )1 1011 414 1014 1030 3 102230 12.

5 121 221 428 1021 230 11 232 10431 230 241 2430 105656 1030 71 2111212151530 1014171 215171 2171 230 15212520302530 202730*30*353560 25344035454060 30405045505060 405460*60*7060*100 506580709075100 6077908010090100 7596110110125125200 100124150125175150200 125156175175200200200 150180225200*2252254 00 2002403002503003004 00 575 VOLT 3-PHASE MOTORS (600V Circuit )1 8111 811 830 3 1014 1016 1016 1030 1021 4230 11 23330 1028 1031 232 1030 24541 230 27871 230 71 291010121230 10111212151530 151720171 2252030 20222525303030 252730*30*353560 30324035404060 40415045605060 5052606070 6060 606275708075100 7577908010090100 10099110110125125200 125125150125175150200 150144175150200175200200192225200* = MOTOR Service Factor* Fuse Reducers Required 100 Amp Switch RequiredMOTOR HPFULL LOAD AMPSWITHOUT OVERLOAD REL AYSWITH OVERLOAD REL AYSSWITCH OR FUSE CLIP R = OR MORE, TEMP RISE NOT OVER 4 0 = LESS THAN OR TEMP RISE MORE THAN 40 = OR MORE.

6 TEMP RISE NOT OVER 4 0 = LESS THAN OR TEMP RISE MORE THAN 40 C120 VOLT 1-PHASE MOTORS (120V Circuit )1 1056 1030 1 471 2730 1 37. 2989930 1 3 2171 230 11620171 2202030 11 2202520252530 2243025303030230 VOLT 1-PHASE MOTORS (240V Circuit )1 221 228 1028 1030 1 232 10431 230 1 2441 241 230 1 1056 1061 4630 3 29830 18109101030 11 2101210151230 2121512151530 31720171 2252030 5283530*353560 71 2405045505060 10506050706060200 VOLT 3-PHASE MOTORS (208V Circuit )1 1032 10330 3 24541 230 1061 4630 11 271 2830 27. 89810930 3111212151530 517. 52020252530 71 *25*3530*60 6060 206 2 .175708075100 3092110100*125110200 40120150125150150200 50150175150200175200 60177200*200*2252254 00 752212502503003004 00 1002853503004003504 00 125359400*400*450450600 150414500450600500600230 VOLT 3-PHASE MOTORS (240V Circuit )1 1021 228 1028 1030 3 24430 256 10530 11 261 471 271 230 29830 2171 220171 230 71 2222525303030 10283530*353560 15425045605060 205460*60*7070100 256880759080100 308010090100100100 40104125110150125200 50130150150175150200 60154175175200200200 75192225200*2502254 00 1002483002503503004 00 1253123503504004004 00 150360450400*450450600 200480600500600600600 Selection of Class RK5 Fuses (FLNR_ID / FLSR_ID / IDSR Series)

7 Or POWR-PRO Class RK1 Fuses (LLNRK / LLSRK / LLSRK_ID Series) Based on MOTOR HorsepowerMotor PROTECTION White PaperDownload our white paper on MOTOR PROTECTION at 2014 Littelfuse POWR-GARD ProductsMotor PROTECTION GuideMOTOR PROTECTION TABLESMOTOR / JTD AMPERE R ATINGMOTOR / JTD AMPERE R ATINGMOTOR / JTD AMPERE R 0 08 1 8 9 011 3 125175 14 4200 021 3 033 3 180250 20 4300 4 24 03504 .11 4 .9 064 288400 312450 36 4 32600 : For severe MOTOR starting conditions, fuses may be sized up to 225% MOTOR (See NEC Article for Exceptions) MOTOR FULL LOAD CURRENT ( )CCMRAMPERE R ATINGFOR MOTORS WITH AN ACCELER ATION TIME OF 2 SECONDS OR LESSFOR MOTORS WITH AN ACCELER ATION TIME OF 5 SECONDS OR LESSFOR MOTORS WITH AN ACCELER ATION TIME OF 8 SECONDS OR LESSMIN.

8 (1)MA X (3)MIN. (1)MA X (3)MIN (2)MA X (3) .. 22 .. (2) (2) 7. 63 7. 3601 Based on NEC requirement limiting the rating of time-delay fuses to 175% of MOTOR , or next higher Based on NEC exception permit ting fuse rating to be increased, but not to exceed, 225% MOTOR , however per NEC Article 4 Class CC (0-30) fuses can now be sized up to 4 00% of MOTOR Based on Lit telfuse CCMR time-delay : These values were calculated for motors with Locked Rotor Current (LRA), not exceeding the following values: MOTOR * 0 0850% 0750% *If MOTOR LRA varies from these values, contact of POWR-PRO Class J Fuses (JTD_ID / JTD Series) Based on MOTOR Full Load AmpsSelection of CCMR Time-Delay Fuses Based on MOTOR Full Load Amps