【Symbol】

   I, Ia, Ib, Ic

【Unit】

   pA , nA, μA, mA , A , kA

   Conversion relationship: 1kA = 1000A, 1A = 1000mA, 1mA = 1000μA,   

1μA = 1000nA, 1nA = 1000pA

【Definition】/【Calculation Formula】

   The quantity of electric charge passing through any cross-section of a conductor in a unit of time is called electric current intensity, commonly referred to as current .

   The electromotive force (EMF) of a power source creates a voltage, which in turn generates an electric field force. Under the influence of this force, charges within the electric field move in a       directed manner, forming an current. A current of 1 ampere (A) is defined as the flow of 1 coulomb of charge per second.

I=Q/t

   For a purely resistive circuit, Ohm's Law states:

I=U/R

【Classification】

   Some common current values:

   Electronic watch: 1.5μA to 2μA

   Incandescent light bulb: 200mA

   Mobile phone: 100mA

   Air conditioner: 5A to 10A

   Lightning: 20kA to 200kA

【Benefits】

  The role of current is to convert electrical energy into other forms of energy. For example, an electric light bulb converts electrical energy into light and heat energy, while an electric motor converts electrical energy into mechanical and heat energy.

  When a bird stands on a single wire with both feet, the voltage difference between its feet is almost zero. Even though the bird is standing on a high-voltage wire (e.g., 10kV), the voltage at both feet is nearly the same, and the bird's body resistance is much higher than the resistance of the wire between its feet (due to the excellent insulating effect of the keratin layer on the bird's feet). Therefore, no current flows through the bird's body, making it safe. Similarly, a person standing on a single conductor will not be electrocuted, as electrocution requires the formation of a conductive circuit.

【Application】

  Series Circuit (n electrical devices in series):

  Current: Itotal=I1=I2=⋯=In (In a series circuit, the current is the same throughout the entire circuit.)

 Parallel Circuit (n electrical devices in parallel):

  Current: Itotal=I1+I2+⋯+In (In a parallel circuit, the total current in the main path is equal to the sum of the currents in each branch.)

  In power supply lines, current measurement requires the use of a current transformer (CT). A current transformer converts the large primary current into a smaller secondary current for measurement instruments. The secondary side of a current transformer must not be open-circuited.

【Product】

  Current, as a basic remote measurement parameter, is commonly denoted by the symbol A in electrical diagrams. The magnitude of current is measured using an ammeter. Except for single-phase voltmeters, the MA series and MS series of instruments from our company are all required to measure current. Depending on the type of meter, they also extend to functions such as harmonic analysis and current unbalance.

【Related Terms】

  Zero-sequence current