Excavator E330D E336D Hydraulic Direction Solenoid Valve Coil

Coil principle

1.Inductance is the ratio of alternating magnetic flux generated in and around the conductor when alternating current passes through the conductor, and the magnetic flux of the conductor to the current that produces this magnetic flux.

2.When DC current passes through the inductor, only a fixed magnetic field line appears around it, which does not change with time; However, when alternating current passes through the coil, the magnetic field lines around it will change with time. According to Faraday's law of electromagnetic induction-magnetic induction, the changing magnetic field lines will produce an induced potential at both ends of the coil, which is equivalent to a "new power supply". When a closed loop is formed, this induced potential will generate an induced current. According to Lenz's law, the total amount of magnetic field lines generated by induced current should try to prevent the change of the original magnetic field lines. Because the original change of magnetic field lines comes from the change of external alternating power supply, from the objective effect, the inductance coil has the characteristic of preventing the current change in AC circuit. Inductive coil has similar characteristics to inertia in mechanics, and it is named "self-induction" in electricity. Usually, sparks will occur at the moment when the knife switch is turned on or off, which is caused by the high induced potential caused by self-induction phenomenon.

3.In a word, when the inductance coil is connected to the AC power supply, the magnetic field lines inside the coil will change all the time with the alternating current, resulting in the continuous electromagnetic induction of the coil. This electromotive force generated by the change of the current of the coil itself is called "self-induced electromotive force".

4.It can be seen that the inductance is only a parameter related to the number of turns, size, shape and medium of the coil. It is a measure of the inertia of the inductance coil and has nothing to do with the applied current.