You can use wattmeters to measure three-phase power. According to 'Blondel's Theorem', you can use one less wattmeter than there are conductors connecting the load to the supply. So, for a three-wire system, you can use two wattmeters but for a four-wire system, you must use three. Check out 'three wattmeter method' and 'two wattmeter method' on the internet to find the necessary connection diagrams.
In a three-phase system, the voltage is measured between any two of the three phase conductors. The voltage between two phases in a 3-phase system is higher at 440v compared to a single-phase system where the voltage is measured between one phase and a neutral wire, resulting in 230v. The higher voltage in three-phase systems allows for more power to be transmitted efficiently over long distances.
Any where that a three phase supply distribution is needed to operate three phase equipment.
Phase to Phase voltageCorrection to the above answer:There is no such thing as a 'phase-to-phase' or 'phase-to-ground' voltage. The correct terms are 'line-to-line' (or 'line voltage') and 'line-to-ground' (or 'phase voltage'). Transmission-line voltages are line-to-line (or 'line') voltages.
Three-phase 408V systems typically use alternating current (AC).
The (ideal) voltage is 480V line to line. The line to neutral voltage (if it is a grounded system - 4 wires) is 480 / 1.732 = 277 volts. The actual measured voltage may be slightly higher or lower than this.
You can't. Currents in three-phase systems are measured in each of the individual line conductors.
In a three-phase system, the voltage is measured between any two of the three phase conductors. The voltage between two phases in a 3-phase system is higher at 440v compared to a single-phase system where the voltage is measured between one phase and a neutral wire, resulting in 230v. The higher voltage in three-phase systems allows for more power to be transmitted efficiently over long distances.
Any where that a three phase supply distribution is needed to operate three phase equipment.
Electric power is measured in watts. It does not matter if it is single phase or three phase. All things being equal, for the same load, the power measured in a single phase circuit or a three phase circuit, will be the same.
Any two legs of a three phase system are classed as single phase. So yes a single phase motor will operate when connected. Be sure to use the proper motor protection devices to control the motor.
There are no three phase 120 volt systems.
All high-voltage distribution systems are three-phase. Single-phase 'spurs' off the main line, supplying, for example, farm houses, are simply two lines of a three-phase system.
I think you mean 'single-phase supply', rather than 'phase supply'. All high-voltage a.c. transmission and distribution systems are three-phase systems. This is because, for a given load, a three-phase system uses less copper than a single-phase system. Three-phase generators produce three 'phase voltages', each displaced, by 120 electrical degrees. These voltages are produced in three windings which are electrically connected in what is called a 'delta' configuration, with each 'corner' of the delta connected to the transmission system by 'line' conductors. Three-phase systems are either 'three-wire' or 'four-wire' systems. Generally, three-phase, three-wire, systems are used for high-voltage transmission and distribution, whereas three-phase, four-wire, systems are typically (but not always) used for low-voltage distribution. Three-wire systems comprise three conductors called 'line conductors'; four-wire systems comprise three 'line conductors' and a 'neutral conductor'. Depending the voltage standards used in the country in which you live, a single-phase supply is obtained either by connecting single-phase load between any two line conductors, or between any one line conductor and the neutral conductor.
Polyphase systems are used because they allow the efficient transmission of electric power, in terms of power transmitted per kilogram of wire. Polyphase systems with more than three phases are very uncommon.
Phase to Phase voltageCorrection to the above answer:There is no such thing as a 'phase-to-phase' or 'phase-to-ground' voltage. The correct terms are 'line-to-line' (or 'line voltage') and 'line-to-ground' (or 'phase voltage'). Transmission-line voltages are line-to-line (or 'line') voltages.
4, 5, or 6 phase systems would cost more than three phase systems in terms of volume of copper required without offering any significant advantages.
In a three phase three wire system, the phase voltage and line voltage are one in the same just different terminology. In a three phase four wire system, the line voltage is higher than the line to ground voltage. Line to ground is, line voltage divided by 1.73 (square root of three). For example 480volts /1.73 = 277 volts.AnswerIt depends upon the configuration of the three-phase system. For a delta (or mesh) connected 3-wire supply system, the line voltage is exactly the same as the phase voltage. For a wye (or star) connected 4-wire supply system, the line voltage is 1.732 (the square-root of 3) times the phase voltage.By way of explanation, for both wye and delta systems, phase voltages are measured across the windings of a three-phase transformer or across individual loads, whereas line voltages are measured between lines. For a wye-connected system, phase voltages can also be measured between any line and neutral.