What is a three phase power system?

It is a property of three phase power systems that if each of the three hot conductors has a nearly equivalent load, that the neutral current will be nearly zero due to the fact that each phase current is "out of phase" with the other. In other words, the load currents "cancel out" in the neutral wire.

What causes current unbalance in a 3 phase system?

Some of the reasons for current unbalance (or imbalance) are: In three phase system, voltage unbalance occurs when phase or line voltage differ from nominal balanced condition. Normal balanced condition is when the three phase voltages are identical in magnitude and are displaced 120 degree vectorially.

What happens if a power supply draws too much?

The exact behavior beyond that basic statement depends on too many things. But for sure, if the load draws more than the supply can put out, the voltage will go down. That much is safe to say. Varies. Shuts down, foldback, hick-up or constant current limit. Do you have a datasheet for it or have you asked the manufacturer?

What happens if power is constant and current increases?

When short circuit occurs, there will be no resistance or reactance and current will be too much high. In this case, when power is constant and current increases, voltage will be decreased. To understand this basic point, let consider the following example. Suppose, (In normal condition) Power = P = 1000 Watts Voltage = V = 110 Volts

Can normal motor overload protection fail detecting single phase condition?

A possible scenario where normal motor overload protection could fail detecting single phase condition is when motor is lightly loaded. Say for example motor is only loaded to 50%. Then motor current in per unit will be 1*0.5= 0.5pu. Healthy phases will see 0.5*1.73= 0.865 pu of current only.

Why does 3rd harmonic current flow on neutral conductor?

An incorrect wiring connection or 3-phase load unbalance issue may cause resultant current flowing on neutral conductor. Apart from these possibilities, high 3rd harmonic current present on each phase may also cause high neutral current. Why does 3rd harmonic current result in current on the neutral conductor?