# 3 phase load calculation formula

This would be an easy spreadsheet to make for single phase. If you are calculate load then you would not use the mca. Single & Three Phase Line kVA calculator is an online tool used in electrical engineering to measure the unknown quantity by two known quantities applied to the below formulas for single phase and three phase connection. The loads are all HVAC equipment that will be continuous loads. Perform a three-phase power calculation using the formula: P = √3 × pf × I × V. Where pf is the power factor, I is the current, V is the voltage and P is the power. Parameters:. I have a 3 phase panel with 7 different 208V/1 phase loads. Total each column of A,B,C?s to view the balance of each, similar to below the put the math in from Art 220 for the totals at the bottom of the spreadsheet. For example, assume any balance 3-phase load with 10 amps of line current and a PF of 0.866 (30° ) lagging. Three phase is not impossible but the formula for total amps is a little more tricky for three phases that are not the same load per phase. kwired Electron manager. Thanks! In this tutorial we’re going to be learning more about three phase electricity. The current in AC systems continually varies in amplitude (i.e., size) and direction, and this variation generally … Full load current calculation for a 3-phase AC supply: The full load current for a 3-phase load in kW is calculated as: $$I=\displaystyle\frac{1000 \cdot S_{kW}} {\sqrt{3} \cdot V_{LL} \cdot \cos{\phi} }$$ Where: S kW: Is the rated power in kilowatt (kW) V LL: Is the line-to-line (phase-to-phase) voltage in volts. Three phase electricity. If I reduce them by .8, and then multiply by 208V, that will give me a 4992VA load to each of two phases? All three phase voltages are equal in magnitude; All phase voltages are in phase by each other i.e. If you balance the load each phase carries 1.73 times the single phase current. For a better experience, please enable JavaScript in your browser before proceeding. Single- and three-phase power are both terms describing alternating current (AC) electricity. If system sequence is {1-2-3} and V12 is reference, then I1=10∠ -60°; I2=10∠ 180°; I3=10∠ 60° . Create an Excel spreadsheet just like a panel schedule with A,B,C phases on the left and right 22 +/- down each side. Then what do you do with 3 different currents all single phase 208V, If you assume the load was balanced 3 x 18.2 = 54.6. Back to basic, below are the simple Electric Power formulas for Single Phase AC Circuit, Three Phase AC Circuits and DC Circuits. Mar 27, 2011 #5 KHall said: I have a 3 phase panel with 7 … Formula to calculate power, current and voltage in three-phase wiring (unbalanced load, different loads on each of three phases) : Pt=P1+P2+P3 P1=V*I1*cosφ1 I1=P1/(V*cosφ1) Same thing for each phase… V=P1/(I*cosφ1) Pt = total power of the circuit in watt (W) P1, P2, P3 = power of phase 1, phase 2 and phase 3 in watt (W) For example, a three phase circuit using 25,000 watts of power and a line voltage of 250 will have a current flow of 25,000/(250 x 1.73), which is equal to 57.80 amperes. Calculating the balanced portion of the load ... ?There are (3) 208V/1ph Heat Pumps rated 30 MCA. Three-phase line-to-neutral voltages actually exist in wye configurations; whereas, they are theoretical in delta configurations. I applied that amount (6240) to each of the two phases that circit is connected to. I have a 3 phase panel with 7 different 208V/1 phase loads. Total Power. Location NE Nebraska. Perform a three-phase power calculation using the formula: P = √3 × pf × I × V. Where pf is the power factor, I is the current, V is the voltage and P is the power. Electric Power Formulas & Equations in DC and AC 1-Φ & 3-Φ Circuits. Important concepts: Line currents for both wye and delta balanced 3-phase loads are calculated using the following relationships; AC input power = 3 x (Vline) x (Iline) x PF PF is the cosine of the angle by which line currents lead or lag the line-to-neutral voltage. 360°/3 = 120° A three phase balanced load is a system in which the load connected across three phases are identical. If your calculator doesn’t have a square root function, use 1.73 as an approximation of the square root of 3. What is the individual VA ratings of the 7 individual circuits. For three phase circuits the power factor is the square root of 3. I like that. That is where I was going with my question. Total each column of A,B,C?s to view the balance of each, similar to below the put the math in from Art 220 for the totals at the bottom of the spreadsheet. There-phase power calculation: The three-phase apparent power $$S_{kVA}$$ is calculated as: $$S_{kVA}=\dfrac{ \sqrt{3} \cdot V_{LL} \cdot I}{ 1000 }$$ The three-phase active power $$P_{kW}$$ (real power) is calculated as: $$P_{kW}=\dfrac{\sqrt{3} \cdot V_{LL} \cdot I \cdot \cos \phi } { 1000 }$$ You can reduce the feeder/service net computed load for 3-wire, single-phase or 4-wire, 3-phase systems that supply linear loads for that portion of the unbalanced load over 200A, by a multiplier of 70%. I hope I got this part of it right. Formula to calculate power, current and voltage in three-phase wiring (balanced load, equal loads on each of three phases) : P=√3*U*I*cosφ I=P/(√3*U*cosφ) U=P/(√3*I*cosφ) P = power in watt (W) U = voltage in Volt (V) I = current in ampere (A) cos φ = cosinus phi (without unit) The relationship between kVA and kW is the power factor (pf):Single phase system - this is the easiest to deal with. Correct? For pure resistive load and power factor = 1 the real power in a 400/230 voltage (line to line / line to neutral) 20 amps circuit can be calculated as W applied = 3 1/2 (400 V) (20 A) 1 = 13856 W = 13.9 kW. JavaScript is disabled. Also Read : 360°/3 = 120° All three phase Currents are equal in magnitude; All phase Currents are in phase by each other i.e. I think they are as balanced across all three phases as much as possible. Example - Pure Resistive Load. Current (I): Enter the the current in Amperes (A). The seven loads are not equal. The product of the voltage and current is the apparent power and measured in VA (or kVA) . Only question is does the totals for each phase factor in the 1.73 multiplier for three phase. I calculated the load for each 2 pole circuit by multiplying the load amps by 208. The current is simply the kVA divided by the voltage. To calculate kVA, you need to enter the known values of voltage and the current into the respective fields. Single-Phase vs. Three-Phase Power . I see it as simply 18242va/ 208 but I am not sure that is correct. 208x30=6240VA. The full load current for a 3-phase load in kVA is calculated as: I could also see you actually having a total load of about 26 KVA depending on how you came up with the numbers you posted. Power factor (cosΦ). To see how this would work for an actual installation, determine the neutral demand load for a balanced 400A, 3-wire, 120/240V feeder. Enter the power factor of the load. I need help to understand how to take the A,B, & C volt-amp totals and convert that to a single amperage figure for calculating my feeder and equipment sizes. W = 3 1/2 U I (2) Brake Horsepower. Given the kW and power factor the kVA can be easily worked out. Again, assuming unity PF and solving this equation for “I,” you get: For 3-phase systems, we use the following equation: kW = (V × I × PF × 1.732) ÷ 1,000. The power taken by a circuit (single or three phase) is measured in watts W (or kW). The three phase power calculator calculates the active and reactive power current from the following parameters: Voltage (V): Enter the phase-to-phase ($$V_{LL}$$) voltage for a 3-phase AC supply in volts. Create an Excel spreadsheet just like a panel schedule with A,B,C phases on the left and right 22 +/- down each side. Calc at full MCA and largest motor as energy recovery vent. I calculated the load for each 2 pole circuit by multiplying the load amps by 208. I calculated the individual circuit rating by taking the load current and multiplying by 208. For example, one heat pump has a MCA of 30A. I see you as reporting a total of about 52.7 KVA. We’ll cover how 3 phases are generated, what a Cycle and Hertz mean, plot the voltage wave form as it’s being generated, calculate our single phase and three phase voltages. NOTE: Direct Current formulae do not use (PF, 2, or 1.73); Single phase formulas do not use (2 or 1.73); Two phase-four wire formulas do not use (1.73); Three phase formulas do not use (2) * For three-wire, two phase circuits, the current in the common conductor is 1.41 times the current in either of the other two conductors.