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Approximate Full Load Amperes Three Phase AC Motors


 		 MOTOR R. P. M.
Horse Power VOLTS 3800 1800 1200 900
1/2 230
 		 1.72 2.15 2.38
460
 		 .86 1.08 1.19
3/4 230
 		 2.46 2.93 3.26
460
 		 1.23 1.46 1.63
1 230 2.80 3.56 3.76 4.30
460 1.40 1.78 1.88 2.15
1 1/2 230 4.36 4.86 5.28 5.60
460 2.18 2.43 2.64 2.80
2 230 5.60 6.40 6.84 7.90
460 2.80 3.20 3.42 3.95
3 230 8.34 9.40 .20 11.40
460 4.17 4.70 5.12 5.70
5 230 13.50 14.40 15.80 15.90
460 6.76 7.21 7.91 7.92
7 1/2 230 19.50 21.50 21.80 23.00
460 9.79 10.70 10.90 11.50
10 230 25.40 26.80 28.00 30.50
460 12.70 13.40 24.00 15.20
15 230 36.40 39.20 41.40 44.50
460 18.20 19.60 20.70 22.20
20 230 50.40 51.20 52.80 54.90
460 25.20 25.60 26.40 27.40
25 230 60.80 64.80 65.60 67.30
460 30.40 32.40 32.80 33.70
30 230 73.70 75.60 78.80 81.80
460 36.80 37.80 39.40 40.90
40 230 96.40 101.00 102.00 105.00
460 48.20 50.50 50.60 52.50
50 230 120.00 124.00 126.00 130.00
460 60.00 62.00 63.00 65.00
60 230 143.00 149.00 150.00 154.00
460 71.50 74.50 75.00 77.00
75 230 179.00 183.00 184.00 193.00
460 89.60 91.50 92.00 96.50
100 230 231.00 236.00 239.00 252.00
460 115.00 118.00 120.00 126.00
125 230 292.00 293.00 298.00 305.00
460 146.00 147.00 149.00 153.00
150 230 343.00 348.00 350.00 365.00
460 171.00 174.00 175.00 183.00
200 230 458.00 452.00 460.00 482.00
460 229.00 226.00 230.00 241.00


 

E = Voltage / I = Amps /W = Watts / PF = Power Factor / Eff = Efficiency / HP = Horsepower

AC/DC Formulas
To Find Direct Current AC / 1phase
115v or 120v		 AC / 1phase
208,230, or 240v		 AC 3 phase
All Voltages
Amps when
Horsepower is Known		 HP x 746
E x Eff		 HP x 746
E x Eff X PF		 HP x 746
E x Eff x PF		 HP x 746
1.73 x E x Eff x PF
Amps when
Kilowatts is known		 kW x 1000
E		 kW x 1000
E x PF		 kW x 1000
E x PF		 kW x 1000
1.73 x E x PF
Amps when
kVA is known		   kVA x 1000
E		 kVA x 1000
E		 kVA x 1000
1.73 x E
Kilowatts I x E
1000		 I x E x PF
1000		 I x E x PF
1000		 I x E x 1.73 PF
1000
Kilovolt-Amps   I x E
1000		 I x E
1000		 I x E x 1.73
1000
Horsepower
(output)		 I x E x Eff
746		 I x E x Eff x PF
746		 I x E x Eff x PF
746		 I x E x Eff x 1.73 x PF
746


 

 

Electric Power Formulas

W = E I         (1a)

W = R I2         (1b)

W = E2/ R         (1c)

where

W = power (Watts)

E = voltage (Volts)

I = current (Amperes)

R = resistance (Ohms)

Electric Current Formulas

I = E / R         (2a)

I = W / E         (2b)

I = (W / R)1/2         (2c)

Electric Resistance Formulas

R = E / I         (3a)

R = E2/ W         (3b)

R = W / I2         (3c)

Electrical Potential Formulas - Ohms Law

Ohms law can be expressed as:

E = R I         (4a)

E = W / I         (4b)

E = (W R)1/2         (4c)

Example - Ohm's law

A 12 volt battery supplies power to a resistance of 18 ohms.

I = (12 Volts) / (18 ohms)

    = 0.67 Ampere

Electrical Motor Formulas

Electrical Motor Efficiency

μ = 746 Php / Winput         (5)

where

μ = efficiency

Php = output horsepower (hp)

Winput = input electrical power (Watts)

or alternatively

μ = 746 Php / (1.732 E I PF)         (5b)

Electrical Motor - Power

W3-phase = (E I PF 1.732) / 1,000         (6)

where

W3-phase = electrical power 3-phase motor (kW)

PF = power factor electrical motor

Electrical Motor - Amps

I3-phase = (746 Php) / (1.732 E μ PF)         (7)

where

I3-phase = electrical current 3-phase motor (Amps)

PF = power factor electrical motor

Allowable Ampacities Insulated Conductors (In a Raceway)

Table 310-16 1996 N.E.C.


 		 60°C 75°C 90°C 60°C 75°C 90°C
AWG
 		 THW
 
 		 THW
 

 		 TW THWN
 		 TW THWN
 
MCM UF USE THHN UF USE THHN

 		 COPPER
 		 ALUMINUM
18

 

 		 14*

 

 

 
16

 

 		 18*

 

 

 
14 20* 20* 25*

 

 

 
12 25* 25* 30* 20* 20* 25*
10 30* 35* 40* 25* 30* 35*
8 40 50 55 30 40 45
6 55 65 75 40 50 60
4 70 85 95 55 65 75
3 85 100 110 65 75 85
2 95 115 130 75 90 100
1 110 130 150 85 100 115
1/0 125 150 170 100 120 135
2/0 145 175 195 115 135 150
3/0 165 200 225 130 155 175
4/0 195 230 260 150 180 205
250 215 255 290 170 205 230
300 240 285 320 190 230 255
350 260 310 350 210 250 280
400 280 335 380 225 270 305
500 320 380 430 260 310 350
600 355 420 475 285 340 385
700 385 460 520 310 375 420
750 400 475 535 320 385 435

* Unless otherwise specifically permitted elsewhere in the National Electrical Code Book, the overcurrent protection for conductor types marked with an asterisk shall not exceed 15 amperes for No. 14, 20 amperes for No. 12 & 30 amperes for No. 10 copper; or 15 amperes for No. 12 & 25 amperes for No. 10 aluminum & copper-clad aluminum after any correction factors for ambient temperature & number of conductors has been applied.

 



Serving the Property Owners in these areas:    ask the electrician, three phase, two phase, single phase, commercial, industrial, power, 480V., 208V., 120V., 277v., transformers, high voltage, pad mount, underground, aerial service, utility service, step up, step down, service entrance panel, noise, parking lot, circuit breakers, fused disconnects, electrician, transformer, Media 19063A, Ardmore 19003, Aston 19014, Bala Cynwyd 19004, Berwyn 19312, Blue Bell 19422,  Bridgeport 19405, Broomall 19008, Bryn Mawr 19010, Conshohocken 19428, Devon 19333, Drexel Hill 19026. Folcroft 19032, Frazer 19355, Havertown 19083, King of Prussia 19406, Lansdowne 19050, Lima 19037, Malvern 19355, Marcus Hook 19061, Media 19063,  Morton 19070.  Narberth 19072, Newtown Square 19073, Norwood 19074, Norristown 19401, Paoli 19301, Plymouth Meeting 19462, South Philly 19145, 19148, Springfield 19064, Swarthmore 19081, Upper Darby 19082, Valley Forge 19481, Wayne 19087, West Chester 19380, Yeadon 19050, Middletown, Lower Merion, Marple, Radnor, control, panel, control systems, Newtown Square 19073, Aston, buss, duct, distribution, industrial, aluminum, Conshohocken, Morton, Springfield 19064,primary service, Delaware County, Delco, generator power, generator service, Philadelphia, PA, secondary, 4160, 13200, King of Prussia 19406, Malvern 19355,electric baseboard heaters, hydronic, fan forced, wall heater, kickspace heater, exhaust, vent, restaurant, rooftop, attic, air, cooling, fans.  We cover areas surrounding:  Delaware County, Delco, Chester County, Montgomery County, Philadelphia, P


Anthony Tori - The electrical contractor.  The Able Group Inc.  610-853-8311.

 
 
       
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