If two phases are shorted together, you will get a phase to phase fault, which will cause protective devices to operate (fuses, relays, breakers, etc.).
CommentThere is no such thing as a 'phase-to-phase' voltage, although the term is frequently, but misguidedly, used in the field. The correct term is 'line-to-line' voltage, because phases exist between lines.
A load current is a current drawn by an electrical load. In other words, it is the current flowing from the source to the load.For a single-phase system, a line current is a current flowing through the line, or 'hot', conductor, while the current through the neutral conductor is called the neutral current.For a three-phase system, the three 'hot' conductors between the load and the source are called 'lines' and, so, the currents passing through them are called 'line currents'. For a three-phase system, loads are either connected between line conductors (delta-connected system) or between each line and the neutral (star- or wye-connected system), and represent the phases -so the currents passing through the loads are called 'phase currents'.For a balanced three-phase system, the line current is 1.732 times the value of a phase current, where the phases (loads) are connected in delta. For phases (loads) connected in star (or 'wye') the line current is numerically-equal to the phase currents.
A phase current is the current passing through a phase, whereas a line current is the current flowing through a line.In the case of a balanced delta-connected load, IL = 1.732 IP. In the case of a balanced star-connected load, IL = IP.For unbalanced loads, these relationships don't hold true, and must be individually calculated.
The line current would be the same if the motor were connected in delta. The current can be based on the rule of thumb which says 7 amps must be allowed for a 1-HP single-phase motor on 240 v. A 2.2 kW motor is three times as powerful, and on a three-phase supply of the same voltage (240/415) it would draw 7 amps.
A 7.5 kW three phase load will be balanced by the manufacturer. When connected to a three phase source the line current on each phase will be equal.
A current transformer has to have the same ratio as the meter that it drives. Full scale deflection on the meter is 5 amps which equals the maximum allowed current on the phase that it is reading. A different ratio on the CT to meter would show an erroneous reading on the meter depending on the ratio of the connected CT. To keep costs down the meter is common to all three phases and is read by connecting the meter to the phase CT through a three position switch.
Star (or wye) connection is where each of the three phases has a fourth conductor, neutral, as its current return. Current flow in this configuration is phase to neutral, which is also grounded back at the distribution center. There will be five total connections, phase A, B, and C, neutral, and (protective earth) ground. Delta connection is where each of the three phases uses the prior phase as its current return. Current flow in this configuration is phase to phase, and there is no neutral, though there is still a ground. There will be four total connections, phase A, B, and C, and (protective earth) ground.
any more load will add to that phase ,over current protection will trip the generator.
If a motor is connected in star, the current in the motor winding will be equivalent to the line current. If the motor is connected in delta, the current will be 1/sqrt(3) of the line current. If three phase CTs are connected in Delta, their secondary current will be sqrt(3) higher than the CT ratio implies by the line current.
This is called a "line-to-line" short and it will trip either the main circuit breaker in the panel, or the fuse protecting the panel. It might also result in personal injury if someone is in contact with the equipment when the short happens. Equipment or damage is also possible.
Three-wire transmission is used on balanced three-phase systems when the current is known to be equal in all three phases, for example when supplying a three-phase motor. A fourth neutral wire is used when the system is liable to have unequal currents or when multiple single-phase supplies are connected to it.
You use three CTs, one per line conductor, each feeding a separate ammeter,
There is no neutral in a delta connection, because that is the definition of delta, a power configuration where current flows from phase hot to phase hot. The loads are A-B, B-C, and C-A. Contrast this with star, where there is a neutral, and the loads are A-N, B-N, and C-N.