Fuse Selection Charts

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SELECTING FUSEGEAR H.R.C FUSE – LINK

For the protection of 3 – Phase Induction Motors

FULL LOAD CURRENTS OF 3 PHASE INDUCTION MOTORS AT VARIOUS VOLTAGES.

NOTE: The following values of full load current were compiled using average efficiencies and power factors.

H.P.Rating K.W On Temp

FULL LOAD CURRENTS AT VOLTAGES SHOWN

220 V 240 V 380 V 415 V 550 V
1 0.75 3.6 3.3 2.1 1.9 1.5
1.5 1.1 4.7 4.3 2.7 2.5 1.9
2 1.5 6.4 5.9 3.7 3.4 2.6
3 2.2 9.1 8.3 5.3 4.8 3.6
4 3 12.1 1.1 7 6.4 4.9
5 3.75 14.6 13.4 8.5 7.8 5.9
7.5 5.5 21.8 20 12.6 11.6 8.7
10 7.5 27.2 25 15.8 14.4 10.9
12.5 9.4 32.6 30.1 18.9 17.3 13
15 11 39.7 36.5 23 21.1 15.7
20 15 52 48 31 28 21
30 22 78 72 45 41 31
35 26 92 84 53 48 37
40 30 105 96 61 55 42
45 34 118 108 68 62 47
50 37 131 120 76 69 52
60 45 157 144 91 83 53
70 53 183 168 106 97 73
80 60 207 190 120 110 83
90 68 232 212 135 123 93
100 75 258 235 149 136 103
125 94 317 290 188 171 127
150 110 377 345 218 200 151
175 132 436 403 252 231 117
200 150 496 454 288 263 198
AVERAGE EFFICIENCIES AND POWER FACTORS OF ELECTRIC MOTORS
Motor Current A.C.1-p.h A.C.3-p.h
A=(H.P*746)/(v*Eff*Cos$*os$) A=(H.P*746)/(v*Eff*Cos$*3)
B.H.P. OF MOTOR ALTERNATING CURRENTS
SINGLE PHASE TWO PHASE THREE PHASE
Eff P.F Eff. P.F Eff.
1 0.65 0.8 0.73 0.79 0.7
5 0.78 0.83 0.84 0.84 0.81
10 0.81 0.84 0.87 0.86 0.85
20 0.83 0.85 0.88 0.88 0.85
50 0.85 0.87 0.91 0.9 0.86
75(&larger) 0.86 0.88 0.92 0.91 0.87

RECOMMENDED RATING OF FUSES

DIRECT-ON-LINE START ASSISTED START
Motor Full load Current Amp   Fuse-link   Motor Full Load Current Amp Fuse-link
From To Rating Amp From To Rating Amp
0 0.9 2 0 1.8 2
1 1.3 4 1.9 2.5 4
1.4 1.9 6 2.6 3.7 6
2 2.6 10 3.8 5.1 10
2.7 5.2 16 5.2 10.3 16
5.3 7.8 20 10.4 14.6 20
7.9 10 25 14.7 18.6 25
10.1 11.8 32 18.7 22.6 32
11.9 15.7 40 22.7 29.2 40
15.8 19.3 45/50 29.3 35 45/50
19.4 22.9 50 35.1 42.8 50
23 28.6 63 42.9 55 63
28.7 41.4 80 55.1 74.2 80
41.5 54.3 100 74.3 97.3 100
54.4 71.5 125 97.4 125 125
71.6 94.4 200 125.1 150 200
94.5 127 225 150.1 180 225
127.1 164 300 180.1 225 300
164.1 186 350 225.1 250 350
186.1 307 400 250.1 350 400
Nominal VN1=7.2kV/440V
Transformer data Primary current Secondary current HT Fuse Rating
Min Max
KVA AAAA
504.872 10 16
75 7.2 10016 25
100 9.6 144 16 25
125 12 1802540
160 15.4 2312540
20019.328940 63
250 24 3604063
315 30 455 63 100
400 38.5 577 63100
50048722 80160
63061910100200
800771154125200
1000961445160250
12501201800200315
16001542310250315
20001932890315400
Nominal VN1=12kV/440V
Transformer data Primary current Secondary currentHT Fuse Rating
Min Max
KVAAAAA
502.9 72 6 10
75 4.31081016
1005.81441625
1257.21801640
160 9.22311640
20011.52902540
25014.43603240
31518.24554063
400235764063
50028.972050100
63036.491063100
80046116080160
1000581440100160
1250721880100200
1600922310160250
20001152900160250
Nominal VN1=24kV/440V
Transformer data Primary current Secondary current HT Fuse Rating
MinMax
KVAAAAA
501.4 7266
752.110866
1002.9 144610
1253.61801010
1604.62311016
2005.82891016
2507.23601625
3159.14552540
40011.55762540
50014.47203240
63018.29103263
100029144040100
125036188050100
160046231063160
2000582900100160
Nominal VN1=36kV/440V
Transformer data Primary current Secondary currentHT Fuse Rating
Min Max
KVA AAAA
501 7266
75 1.5108 66
1001.914466
1252.4180610
1603.1231610
2003.82891016
2504.83601016
3156.14551625
4007.75761625
5009.67202540
63012.29102540
80015.411603263
100019.314403263
125024188040100
160031231050100
200038290063100

Note on selection of HT fuses for HT motor Protection

Due to their relatively special current-characteristic PANICKKER HT fuses are excellently suited for protecting HT-motors with normal and difficult starting conditions. The suitable motor fuse for certain operating conditions can be taken from illustration fig 1 to 3. The nominal current of the HT fuse to be found is taken from the ordinate and depends on the motor starting current Istart (abscissa value) and the frequency of starts (parameter value) for the various run-up periods of a motor of 6 s, 15 s and 60 s. the digits 2, 4, 6, 10, 15 and 30 along the individual characteristics stand for the number of motor starts within one hour time. In case Panickker HT fuses are used in conjunction with vacuum contactors for protecting H.T-motors, it must be born in mind that these vacuum-contactors are only designed for switching currents up to the rated current of contactor. Shot-circuit protection must therefore be taken care by the HT fuses To avoid the contact-welding of the contactors, the maximum cut-off current of the HT fuse used must always be lower than the dynamic current the contactor can take , this value to be checked with the manufacture of contactor before application. In case of doubt, please mention starting current, starting period and starting frequency per hour of the motor to be protected with fuses. Also the dynamic current of the contactor to be provided for our technical support. Cut off current curves of fuses are given below

Fig1
Fig2
Fig3
HT-Curve-1
HT-Curve-2
HT-Curve-3
curve_new
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