The single- phase voltages are phase to neutral voltages. The current calculated is the line current - if you place an ammeter in the circuit, this is what you will measure. Your correct it is the RMS current. Calculation of Power in a Balanced Three Phase Circuit ..... 20 4C. The phase voltage is 400/ √(3) = 230 V. To convert kW to kVA you need the power factor (you could just use kW, but you would have some error). Formulas Used: Three phase = I x V x 1.732 / 1000 One / single phase = I x V / 1000 Where, I = Amps V = Volts Example: Calculate kVA value for three phase voltage of 5 v and 8 amps. Current won't flow through the fault to the load (or very little will). By the way, I think you probably wanted to say 230 V (not 210 V) if VLL is 400 V. How to get power factor three phase motor specification as below. Real Power. = (kW x √3) / (3 x pf x VLL) Thanks. Voltage Drop Formula for Steel Conduit. Other things to consider while carrying out calculations may include the efficiency of equipment. Phase B starts at 0 at 120 degrees and Phase C starts at 0 at 240 degrees. Reply. My advice would be to look at your actual situation and analysis it to see the effect of changing from star to delta. More traditionally formulas may be used to give the same result. As far as line and phase currents are concerned, they are related to each other as: Iline=√3IphaseIline=√3Iphase Which means that whatever supply current we have, we will have wire cross-section for 1/√31/√3times line current only. my question is do i need to multiply 80.6a to 1.732 to convert in 3 phase? calculations or measurements and from either phase parameters or line parameters. The... Here’s list of some famous scientists. I line = 0.90 * 1.73 = 1.57 A This figure is a constant found in three phase, as the phases do not generate the same amount of power (simultaneously). I have now changed it to show kVA. Initially, we explored the idea of three-phase power systems by connecting three voltage sources together in what is commonly known as the “Y” (or “star”) configuration.. On the other end multiply 2.pi times the armature rotation speed, then divide the resultant value by 60.    I= P 3 ×pf× V LL. But a different result when using The relationship between kVA and kW is the power factor (pf): Single phase system - this is the easiest to deal with. Businesses that require three-phase power need to add an extra component in the formula to arrive at the correct transformer size, i.e., square root of 3 (√3) or 1.732. I expect it to stay the same. You can target the Engineering ToolBox by using AdWords Managed Placements. To protect the windings of a transformer against overcurrent, use the percentages listed in Table 450.3(B) and its applicable notes. Enter the rated volts, amps, power, and efficiency to find the current flowing through the motor. If you don't have a power factor use 0.9. For 3-phase systems, we use the following equation: kW = (V × I × PF × 1.732) ÷ 1,000. Strictly speaking you should be using kVA (which you can obtain by dividing the watts by the power factor). To convert a  three phase problem to a single phase problem take the total kW (or kVA) and divide by three. That is the current in each phase is the same and each phase delivers or consumes the same amount of power. Turns Ratio = N 1 / N 2 = V 1 / V 2 = I 2 / I 1. Also depends on if it is three phase or single phase and the voltage. = kW / (3 x pf) divided by (VLL/√3) Please can  some body teach me, what is the current across each line of a 167 kVA 3 phase generator with a line voltage of 240 volt, It is a three phase generator, each phase supplies 167/3 = 56 kVA. If you know the kVA and voltage, it is very easy to work out the current. The key to doing this is that the sum of power in each phase is equal to the total power of the system. Formula : Three Phase Electric Power = V * I * 1.732 * PF Where , V = Voltage I = Current PF = Power Factor (0.8) Three Phase Electric Power calculation is made easier here using this online electrical calculator. Phasor Diagrams of Three Phase Circuits..... 22 4D. You can't divide the current by three (power kW or kVA - yes). The load sees this voltage and no current will flow. CM = Circular-Mils (conductor wire gauge) Notes: • The National Electric Code recommends a maximum 3% voltage drop for branch circuits. Hi Steven, Thanks for sharing your knowledge, it really helped me understanding the theory. 3 Phase Induction Motor current calculator is used to calculate the rated and full load amperes of the motor. I have a small 400 V three phase 4 wire (star) installation with the following resistive loads on each; I need to calculate the line current in each of the three phases can some one please help with a formula? ABB that according to their calculation, that 50hz motor would be fine for 60hz system. I like to use kVA as this is just the voltage multiplied by the current. To make the situation confusing, the contractor got the confirmation from the manufacturere. ... To better understand three phase power, a person would be well advised to first review and understand the principles applicable to single phase power. If the system is perfectly balanced I again have no issues figuring out the amps drawn on each leg. As an example, consider a load consuming 23 kW of power at 230 V and a power factor of 0.86: Note: you can do these equations in either VA, V and A or kVA, kV and kA depending on the magnitude of the parameters you are dealing with. On the Star Delta. Given the kW and power factor the kVA can be easily worked out. The National Electrical Code states that the voltage drop of a feeder circuit must not exceed 5%, and the voltage drop of a branch circuit must not exceed 3%. Thanks. dilan, the kVA would be ( 642.24 + 651.85 + 651.84) * 220 = 428102 VA = 428.1 kVA the kW would be 428.1 x 0.86 = 368.2 kW For the breaker, I would likely be looking at 800 A (posibly something like a MasterPact NT or NW, depending on other parameters) and setting the overload protection in the range of 710 A (this is plus 10%).
2020 3 phase voltage calculation formula