The normal way is to use a transformer with a 3-wire primary and a 4-wire secondary. In the UK that happens at electricity substations for example where the 11 kV supply comes in on 3 wires and goes out at to users at 240 v with three phase wires and a neutral.
The current carried by the neutral of a three phase four wire system is the un balanced current. If the three phase system was completely balanced on all three phases there would be no need for a neutral, eg a three phase motor. This neutral current will be less that the phase current so a reduction in the neutral size is allowed.
A delta-connected system is described as being a three-phase, three-wire, system, and doesn't have a neutral. But a balanced star (wye) connected load (e.g. a three-phase induction motor) doesn't actually require a neutral.
A three phase system will have 3 phase branch circuits and no neutral.
As far as I understand, you don't need neutral line for connecting appliances that is 3-phase compilant. You only need the neutral line to connect a single phase appliance, which you connect along with one of the three lines.
Neutral current is the vector sum of the phase currents. You should be able to add up the phase currents from their polar quantities.
In a properly balanced three phase system, there is negligible current on neutral. If there is substantial current on neutral, then the system is not balanced and/or something is wrong.
TPN Load break switch: Is basically a main switch used in three phase system and know as Three pole neutral or Three phase neutral having four connectors for three phases and one neutral.
It is done by connecting the neutral to earth at the transformer that produces the three-phase supply. If the three phase wire supply equal currents, there is no current in the neutral wire and its whole length stays at earth potential, but if there is current in the neutral it produces a small voltage on the neutral at places away from the transformer.
TPN stands for Triple Pole With a neutral link.normally this are the switches which are used in case of three phase connections and as main switch......gonecase17@gmail.com
Because a three-phase system needs half the amount of wire to transmit power compared to three single-phase systems. With a balanced three-phase system the three live wires are phased so that the sum of the currents is always zero, which means that if the three neutral wires are combined, the current in the neutral is zero. Therefore the original three neutral wires can be removed, leaving only the three live wires. In practice a neutral wire is still included in three-phase four-wire systems when the load is potentially unbalanced, as for example in neighbouring houses which use different phases of a three-phase system for their individual single-phase supplies.
The current is the same in the three live wires. The voltage can be described as the line voltage (phase to neutral) or the phase voltage (phase to phase) which is larger by a factor of sqrt(3). So a line voltage of 230 v corresponds to a phase voltage of 400 v.
Line, phase, neutral are terms used to describe the conductors in a three-phase system. The three live wires are called 'lines', and less correctly, 'phases'. Neutral is used for the fourth wire which in a balanced system carries no current.