Why are there two voltage levels of 220 volts and 380 volts at the wellhead?
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Why are there two voltage levels of 220 volts and 380 volts at the pump jack wellhead? Why are there 660 volt and 380 volt transformers? What determines this? I’m not in the electrical field, so I don’t understand much about it.
220V is the phase voltage, while 380V is the line voltage
A three-phase transformer has three sets of windings, one winding for each phase. The three phase windings are connected in a star configuration; the ends of these windings are connected together to form the neutral wire, which is denoted by the letter N. The ends of the three-phase windings lead three phase wires outside the transformer; the voltage level between these three phase wires is 380V, which can provide power for machinery ； The output voltage waveform is a sine wave alternating current with a frequency of 50 Hz, and the three phases are separated by an electrical angle of 120 degrees. The voltage between one of the three phase wires and the working neutral wire is 220V. This is the method used for supplying electricity in our ordinary residential applications, and it is known as single-phase alternating current. When the loads connected to a three-phase power supply are balanced, there is no current in the neutral wire. As a result, the power consumption is balanced; therefore, in three-phase power sockets, the neutral wire is not used, but instead the protective ground wire is connected. In household electricity usage, the load connected to a single transformer is uneven. If the neutral wire for a particular user is broken, there will be no power supply and the electrical appliances will not function. The system’s neutral wire must never be interrupted, as such an interruption can cause voltage levels in some users to exceed 220V, leading to damage to electrical equipment; meanwhile, other users may not receive a voltage level of 220V (the phase with higher loads will experience under-voltage, while those with lower loads will experience over-voltage). Therefore, regulations stipulate that fuses and switches and other electrical devices must not be installed on the neutral wire, in order to ensure safe electricity use for users who rely on a single-phase 220V supply.
220 is the phase-to-ground voltage, while 380 is the line-to-line voltage. .
One phase voltage, one line voltage
Generally, an alternating current frequency of the human body at 30–50 mA can be life-threatening. In China, the maximum safe current flowing through the human body is set at 30 mA (for a grid voltage of 660 V) and 50 mA (for a grid voltage of 380 V).
220V is the voltage between the phase wire and the neutral wire, while 380V is the line voltage