This results in a loud humming sound of the solenoid valve. As a result, the plunger will move back and forth with a frequency of twice the mains frequency. Every time the voltage crosses the zero line, the magnetic force drops to zero. If it would not be used, the plunger would vibrate. In the opposite case, when a 60Hz coil is connected to a 50Hz supply, the energy consumption will increase and the temperature of the coil will increase slightly.Īnother important feature of AC coils is the use of a special conductive ring, called the shading ring, on the upper side of the coil. ![]() A 50Hz coil that is connected to a 60Hz supply, will have a lower magnetic force than specified. The reactance is higher with 60Hz than with 50Hz. The inductive reactance is not only determined by the position of the core, but also by the frequency of the current. The coil can produce too much heat and burn in minutes. As a result, the coil should never be connected to the power supply when the core is removed. The current is lower when the core is in the lifted position. This means that the current through the coil increases. The further the core is removed from the coil, the lower the inductance resistance becomes. The inductive resistance is largely dependent by the position of the core. With AC coils, the current is not only determined by the resistance of the windings, but also by the inductive resistance (reactance). ![]() The electrical resistance of an AC coil is lower than the resistance of a DC coil at the same voltage. It doesnt matter how the coil is connected to the power supply (the poles can be connected both ways). Both coils for AC and DC pull the core towards the centre. ![]() ![]() The core is ferromagnetic (and not a permanent magnet with defined poles), therefore the core will always be attracted to the centre of the magnetic field. Often people think that the direction of the magnetic field in the coil determines the direct of force that acts on the core.
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