Three phase electricity, per watt delivered, is cheaper than single phase. This is because you can deliver the power to an electrical appliance over three "power lines" instead of one. For example, if you tried to operate a 5 hp ac electric motor on single phase it would require 3730 watts for continuous operation and quite a bit more for start up. A 12 gauge standard wire is only rated for 2700 watts. The more current that runs thru a wire the hotter it gets. The hotter it gets the more the resistance (ohms) goes up. Resistance in a wire is pure waste in terms of electrical cost since you are paying to convert electricity to heat. The same motor run on 12 gauge 3-phase wiring would only deliver 1243 watts per electric line to run the 5 hp motor. Also for motor use, three phase is much smoother and "torquier" than single phase since the power pulses to the field magnets is matched far better than in the single phase. For a visual on this see the website description below: = Wikipedia: Three-phase electric power =
Uses more current.
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.
If the phase voltage is 230 V, then (providing you are describing a three-phase, four-wire, system), then the line voltage will be 1.732 larger -i.e. 400 V.
A "three-phase system" is a polyphase system having three phases. The term "polyphase system" just means a system having multiple phases. If it is used by itself, "a polyphase system" doesn't mean "a three-phase system".
A three-phase meter can be used for single phase while the reverse is not the case.
A two-phase system is archaic and you are unlikely to find it in use anywhere these days, so it is mainly of historical interest. A two-phase, three-wire system, consists of two phase voltages, displaced from each other by 90 electrical degrees, and a phase voltage which is 1.414 x phase voltage.A three-phase system consists of three phase voltages which are displaced from each other by 120 electrical degrees. In the case of a three-phase, three-wire, system, the line voltages are numerically equal to the phase voltages; in the case of a three-phase, four-wire, system, the line voltages are 1.732 x phase voltage.
All current is the passage of electric charges from one terminal to another through a conductor so there is no real difference in the type of current that flows in a 3 phase system compared to a single phase system.
Over all losses are less in three phase AC system compared to 1 phase. For a given load (KW) 1 phase system would draw more current
In a single-phase system, one tension is provided by 1 phase and the neutral wire, which is convenient for domestic electricity consumption. As for the 3-phase system, you have 2 voltages: *between any phase and the neutral conductor, you have the PHASE VOLTAGE (V) *between one phase and any other, you get the LINE VOLTAGE (U) ;which is greater than V. Relation between these voltages is: U = V x sqrt[3] The advantage of such a "polyphased" system is obvious, since the electric power is divided into the three phase, you get less Joule loss compared to a single-phase system with the same total power. That's why great consumers of electricity (such as factories) chose to be powered through three-phase.
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.
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.
If the phase voltage is 230 V, then (providing you are describing a three-phase, four-wire, system), then the line voltage will be 1.732 larger -i.e. 400 V.
A "three-phase system" is a polyphase system having three phases. The term "polyphase system" just means a system having multiple phases. If it is used by itself, "a polyphase system" doesn't mean "a three-phase system".
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.
A three-phase meter can be used for single phase while the reverse is not the case.
1. 3 phase is more efficient for electric motors. 2. Electric motors start easier with 3 phase. 3. Less current draw 4. Less heat is produced that is waste.
Because the cost of the conductors. A three phase system can transmit the electric energy at a relative low cost.
A two-phase system is archaic and you are unlikely to find it in use anywhere these days, so it is mainly of historical interest. A two-phase, three-wire system, consists of two phase voltages, displaced from each other by 90 electrical degrees, and a phase voltage which is 1.414 x phase voltage.A three-phase system consists of three phase voltages which are displaced from each other by 120 electrical degrees. In the case of a three-phase, three-wire, system, the line voltages are numerically equal to the phase voltages; in the case of a three-phase, four-wire, system, the line voltages are 1.732 x phase voltage.