In 3 phase machines have L1,L2,L3,N and PE(Protective earth).some time Neutral wire is not connected to the power supply.But,Machine have a neutral wire.What will happen if not connect neutral wire?what is the usage of neutral wire for machines? In the installation neutral wire is note connected.Is it good idea?

  • \$\begingroup\$ Depends on the machine. \$\endgroup\$ – Turbo J Jan 25 '15 at 20:42
  • \$\begingroup\$ Find a diagram for that machine and determine, if the neutral is used. \$\endgroup\$ – sparky Al Jan 25 '15 at 21:24

If the machine is wired for a wye, (L1,L2,L3, and N), you have to supply all of them. If the load is equal between the phases, it could appear that everything is ok, but if one load is larger, or if one fuse blows, you will get wrong voltages, and currents.

If the machine is wired for delta, neutral is not needed. It sounds your machine requires a neutral. Run a new supply including neutral to the machine, or get a delta to wye transformer for that machine. (if you do that, you have to ground the neutral).

The neutral wire carries unbalanced current, and ensures that the load is working on Line to neutral voltage.(fixed voltage). Without a neutral, the voltages will balance according to the loads. In a short, it is a bad idea.


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