Electrist: Voltage Drop Calculator Menu

Custom Materials: Opens a form where custom conductor materials can be edited
Custom Conductor Sizes: Opens a form where custom conductor sizes can be edited

Other

Also at the top of the Voltage Drop calculator is a pop-up menu which allows you to select which conductor units you wish to use. Current options are American wire guage (AWG), metric, or custom (for user-defined sizes such as PCB traces)

Finding voltage drop Vd, percentage of drop, and voltage at load V @ Load
Screenshot

Use the Phases pop-up to select the number of AC phases or a DC circuit
Write in the amount of current I
Select the conductor material
Select the conductor size
Write in the one way length of the circuit, selecting the unit of measure with the pop-up
Use the Amb Temp pop-up to select the ambient temperature

When all values are entered tap the Calc button to display the voltage drop in the field at the top of the form. If you have also entered the source voltage Vs then voltage at load V @ Load and the percentage of voltage drop will be displayed at the top of the form as well.

Finding DC resistance of conductor

Select the conductor material
Select the conductor size
Write in the one way length of the circuit, selecting the unit of measure with the pop-up

When all values are entered tap the DC Res button to display the resistance of the conductor in a pop-up form.

Custom Materials

To create a custom material:

Select Custom Materials from the Options
Tap the New button.
Enter the name of your new custom material
- for example: "Nichrome®"
Enter the specific resistance of the material (aka 'rho'). The unit of measure for rho is Ω-cmil/ft (ohms-cmil/ft):the resistance in ohms of a one foot length of the material with a diameter of 1 circular mil at 20 degrees celsius (actually it is also quite common to see rho expressed in the SI/metric units Ω-m, Ω-cm, µΩ-m, and µΩ-cm. See table below for conversion to Ω-cmil/ft)
- for example: the rho value of Nichrome® is 675 ohm-cmil/ft
Next enter the temperature coefficient of the material at 20 degrees celsius (aka 'alpha')
- for example: the alpha value of Nichrome® is 0.00017
Click the Done button

The material you just entered will now be available in the Material pop-up of the Voltage Drop calculator

RHO AND ALPHA VALUES OF CONDUCTORS These values are presented as examples only and are not to be considered definitive or absolute
Material	Rho	Alpha Ω-cmil/ft	Material	Rho	Alpha Ω-cmil/ft
Silver	9.546	0.003819	Nickel	41.69	0.005866
Copper	10.09	0.004041	Lithium	55.88	0.00435
Gold	13.32	0.003715	Iron	57.81	0.005671
Aluminum	15.94	0.004308	Platinum	63.16	0.003729
Beryllium	19.85	0.0090	Phosphor Bronze [Cu94/Sn6]	66.17	0.0006
Calcium	22.26	0.00457	Lead	123.92	0.0042
Magnesium	25.26	0.00425	Uranium	162.41	0.0034
Rhodium	28.27	0.0044	Nickel Silver [Cu62/Ni18/Zn20]	174.44	0.0003
Sodium	29.48	0.0055	Constantan® [Cu55/Ni45]	312.80	0.00003
Iridium	30.67	0.0045	Manganin® [Cu86/Mn12/Ni2]	290	0.000015
Cobalt	38.14	0.0066	Titanium	324.83	0.0038
Cadmium	43.91	0.0043	Neodymium	384.98	0.00164
Tungsten	31.76	0.004403	Mercury	576.87	0.001
Molybdenum	32.12	0.004579	Nichrome V® [Ni80/Cr20]	650	0.00011
Zinc	35.49	0.003847	Nichrome®	675	0.00017

CONVERSION FACTORS
To Convert	Multiply By	To Get
Ω-m	601529086.939	Ω-cmil/ft
µΩ-m	601529.086939	Ω-cmil/ft
Ω-cm	6015.29086939	Ω-cmil/ft
µΩ-cm	6.01529086939	Ω-cmil/ft

Custom Conductor Sizes

To create a custom Conductor Size:

Select Custom Conductor Sizes from the Options
Tap the New button.
Enter the name of your new custom size
- for example: "8 mil by 0.7 mil PCB trace"
Enter the cross-sectional area of the new size in circular mils (aka 'circular mil area' or 'CMA').
- for example: the CMA of an 8 mil by 0.7 mil conductor would be 71.301384 cmils (see below for information on this conversion)
Click the Done button

To use the conductor size you just entered select Custom from the pop-up at the top of the Voltage Drop calculator after which it will be available in the Size pop-up below.

Converting Measurements:

To convert the cross-sectional area of a rectangular conductor from square mils to CMA (circular mil area) just multiply by 1.273239
If you have a measurement of the cross-sectional area in a unit other than cmils, such as square inches or square mm, you can convert to cmils with a single factor. (See area conversion factors listed below)
Similarly, you can convert the cross-sectional area of any rectangular conductor into circular mils by:
1. Converting it's width and thickness measurements into mils (See linear conversion factors listed below)
2. Multiplying these converted measurements to get the cross-sectional area in square mils
3. Multiplying this result by 1.273239 to get the CMA
You can also convert the measurement of any cylindrically-shaped conductors diameter into circular mils by:
1. Converting the measurement into mils (See linear conversion factors listed below)
2. Square this result to get the CMA

Some Examples:

For the example above of a PCB trace that is 8 mils wide and 0.7 mils thick:
1. Find the cross-sectional area in square mils: 8 * 0.7 = 56 square mils
2. Convert the square mils to circular mils: 56 * 1.273239 = 71.301384 CMA
A bus bar that is 2 inches wide and 3/4 inch thick:
1. Find the cross-sectional area in square inches: 2 * 0.75 = 1.5 square inches
2. Convert the square inches to circular mils: 1.5 * 1273239 = 1909858.5 CMA
- OR -
1. Convert the linear measurements from inches to mils: 2 inches = 2000 mils, 0.75 inch = 750 mils
2. Find the cross-sectional area in square mils: 2000 * 750 = 1500000 square mils
3. Convert the square mils to circular mils: 1500000 * 1.273239 = 1909858.5 CMA
A heater band that is 10 mm wide and 0.5 mm thick:
1. Find the cross-sectional area in square mm: 10 * 0.5 = 5 square mm
2. Convert the square mm to circular mils: 5 * 1973.525 = 9867.625 CMA
- OR -
1. Convert the linear measurements from mm to mils: 10 mm = 393.7008 mils, 0.5 mm = 19.685 mils
2. Find the cross-sectional area in square mils: 393.7008 * 19.685 = 7750.0157 square mils
3. Convert the square mils to circular mils: 7750.0157 * 1.273239 = 9867.622 CMA

CONVERSION FACTORS
AREA			LINEAR
To Convert	Multiply By	To Get	To Convert	Multiply By	To Get
square mils	1.273239	circular mils
square inches	1273239	circular mils	inches	1000	mils
square cm	197352.5	circular mils	cm	393.70078740157	mils
square mm	1973.525	circular mils	mm	39.370078740157	mils
			microns	0.0393700787402	mils
			nm	0.0000393700787	mils
			furlongs	7920000	mils

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