What is meant by Phase Current?
Phase current is the current that flows through the star (or) delta connection of a three-phase system.
It is represented by the symbol Iph.
In addition, this current is described as the current flowing between two phases.
What is the Phase of a Current?
In a 3-phase power supply, phase current is the amount of current passing through each phase load.
Phase Current Formula
The phase current IP in amperes equals the line current IL in amperes divided by root 3.
IP = IL/√3
Where
IP – Phase Current
IL – Line Current
Phase current is calculated if line current divided by 1.732(√3).
Solved Example
Calculate the phase current of a 1000 amp delta-connected alternator output line current.
IP = IL/√3
IP = 1000/√3
IP = 577.367 A (Amps)
Points to Remember
If the system is star-connected,
IP = IL
Line current (amps) equals phase current (amps).
What is the difference between Line Current & Phase Current?
Line Current vs Phase Current
| Line Current | Phase Current |
| A three-phase system’s current flows through its line conductors. | In a three-phase system, current flows through every phase of the load. |
| Typically denoted as IL. | Typically denoted as IP. |
| For Star Connection: IL = IP | For Star Connection: IP = IL |
| For Delta Connection: IL = IP x √3 | For Delta Connection: IP = IL / √3 |
| Measured at the three-phase power supply or system terminals. | Measured within load phases (delta or star connection). |
| Used to specify cable and protective devices for the whole system. | Used to evaluate individual phase loads & balance the system. |
The term “line” refers to the alternating current line. The term “phase” refers to any one of the phases that are present in a multi-phase line.
Line voltage refers to the voltage observable on an alternating current (AC) line, which is normally single phase. Line current is the current generated when a voltage is delivered to a load.
If one have a three-phase line, each phase (a separate wire) has its own voltage, called phase voltage. Again, if one apply a load to a phase, phase current occurs.
Electrical power is distributed via the network, with all transformers and switchgear having three phases (usually).
These three phases form a star or delta. Line current is the current flowing outside the transformer, whereas phase current is the current running through one of transformer (or) generator’s windings.
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