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APPENDIX B — IMPORTANT FORMULA
OHMS LAW:
OHMS = VOLTS / AMPS ( R = E / I)
AMPS = VOLTS / OHMS (I = E / R)
VOLTS = AMPS / OHMS (E = IR)
3 Phase
Resistance = (V² X 2) / W Amperage = W / (V X 1.732)
208V KW 1 5 10 20 25 40 50 100 200 250 400 500
RES 86.5 17.3 8.6 4.3 3.46 2.16 1.73 0.865 0.432 0.346 0.276 0.173
AMP 2.77 13.9 27.8 55.5 69.4 111 139 278 555 694 1110 1388
240V KW 1 5 10 20 25 40 50 100 200 250 400 500
RES 115 23.0 11.5 5.76 4.61 2.88 2.30 1.15 0.576 0.461 0.288 0.230
AMP 2.41 12.0 24.0 48.0 60.0 96.2 120 240 480 600 962 1200
380V KW 1 5 10 20 25 40 50 100 200 250 400 500
RES 289 57.7 28.8 14.4 11.5 7.22 5.77 2.88 1.44 1.15 0.722 0.577
AMP 1.51 7.59 15.2 30.4 37.9 60.7 75.9 152 304 380 608 760
480V KW 1 5 10 20 25 40 50 100 200 250 400 500
RES 460.8 92.2 46.1 23.0 18.4 11.5 9.22 4.61 2.30 1.84 1.15 0.922
AMP 1.20 6.01 12.0 24.0 30.0 48.1 60.0 120 240 300 481 600
1 Phase
Resistance = V² / W Amperage = W/ V
120V KW 1 5 10 20 25 50 100 200 250 500
RES 57.6 28.8 14.4 7.20 4.80 3.60 2.88 1.44 0.720 0.360
AMP 2.08 4.16 8.33 16.7 25.0 33.3 41.7 83.3 167 333
208V KW 1 5 10 20 25 50 100 200 250 500
RES 43.3 8.65 4.33 2.16 1.73 0.865 0.432 0.216 0.173 0.086
AMP 4.80 24.0 48.1 96.1 120 240 481 962 1202 2404
240V KW 1 5 10 20 25 50 100 200 250 500
RES 57.6 11.5 5.8 2.88 2.30 1.15 0.576 0.288 0.230 0.115
AMP 4.16 20.8 41.6 83.3 104 208 417 833 1042 2083
KVA: 1 phase VOLTS X AMPS
3 phase 1.732 X VOLTS X AMPS
Derang KW:
KW(
V2
/
V1
)² = derated KW;
EX. 50KW (
200
/
240
)² = 34.722KW
Derang KW and Hz:
KW (
V2
/
V1
)² X (
F1
/
F2
) = Derated KW at dierent Hz
3 Phase Henrys: V²/(Kvar X 3.14 X freq)
1 Phase Henrys: V²/(2 X 3.14 X freq X vars)
1 Phase Farads: Kvar / (2 X 3.14 X freq X V²)
MA Output
Amps: amps / (833 X 16 + 4) volt: (V2 / V1) X 16 + 4
Heater Current (Wye)
I
H
= W
H
* (V
L-H
/(X
H
*V
H
²))
I
H
= Heater Current
W
H
= Waage of 1 Heater
X
H
= # of Heaters from Line to Neutral
V
H
= Rated Voltage of 1 Heater
Fuses for Transformer
Total Amperage = V*A / Source Voltage
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