3 Phase vs 2 Phase: Difference and Comparison

Electricity is one of the boons of inventions in the late 18th century. Single-phase, double-phase, and triple-phase meters were discovered in time after the advent of electricity to supply a suitable amount of power in structures.

The term phase refers to the distribution of a load of electric appliances connected with a meter. According to the names, wires are present in the power distributor.

For example, there are three-phase wires in three-phase and two-phase wires in two-phase.

Key Takeaways

  1. 3-phase systems use three alternating currents, while 2-phase systems use two, making 3-phase systems more efficient for power distribution.
  2. 3-phase systems are widely used in industrial and commercial applications, whereas 2-phase systems are less common and mainly found in older installations.
  3. 3-phase motors offer smoother and more consistent torque, making them preferable for heavy-duty applications compared to 2-phase motors.

3 Phase vs 2 Phase

A 3-phase system has three conductors, where, the three conductors carry equal and balanced currents that are 120 degrees out of phase with each other, which provides a more efficient power transfer, and are more used in industrial applications. A 2-phase system has two conductors.

3 Phase vs 2 Phase

In the nineteenth century, Mikhail Dolivo-Dobrovolsky found 3 phase power system. It performs all the tasks (transmitting, generating, and distributing) alternative power.

A load of electricity supply is bifurcated among the 3 phases to avoid any power-related mishappening. Moreover, 3 phase electric power is more cost-efficient than single and 2 phase meters.

2 phase electric power consists of two phases (that supply electricity in a building). These power distributors came into the existence in the late 1800s.

Mostly, four wires are present in this system. Each phase contains two wires. Three wires are present in some of the 2 phase systems. One is for each phase, and the third is for the common wire.

Comparison Table

Parameters of Comparison3 Phase2 Phase
DefinitionThe three-phase meter is one in which power is dispersed across three phases.The 2 phase meter distributes power into two phases.
Invented ByA Russian Engineer Mikhail Dolivo-Dobrovolsky invented it.A group of expertise (Charles Proteus Steinmetz and Elihu Thomson) is behind the invention of 2 phases.
Phase AngleThe phase angle of 3 phase power system is 120 electric degrees.The phase angle of 2 phase system is 90 electric degrees.
When to Install3 phase power system is installed when the electricity consumption of buildings is more than 10 kilowatts.2 phase electric system is preferred when the consumption of electricity is less than 10 kilowatts.
CostThe 3 phase electric system is cheap comparatively.The 2 phase electric power system is more expensive than 3 phase system.

What is the 3 Phase?

Mikhail Dolivo-Dobrovolsky discovered three-phase power in the nineteenth century. It is for transmitting, generating, and distributing alternative power.

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It falls under the category of a polyphase system (which was invented by multiple people (Galileo Ferraris, Mikhail Dolivo-Dobrovolsky, Jonas Wenström, John Hopkinson, William Stanley Jr., and Nikola Tesla).

The three phases are placed symmetrically and consist of three conductors. The conductors carry the same frequency and voltage towards the same reference. These phrases diverge at the phase angles.

The sum of the three conductors’ instantaneous currents equals zero. It means the amount of electric current in one of the conductors is equivalent to the total current in the other two conductors.

The mathematical sign of a single conductor and the sum of the conductor is opposite. Phase 1, for example, has a supply of +240 V current. Current in the other two phases will be (-120 V) each.

Sum =+ 240 + (-120) + (-120)= 0

If a three-phase system tends to have a fourth wire, it is a neutral wire. The three-phase electrical power supplies more power density than single-phased or 2 phase at the same amperage.

Since it can handle a high load, it is installed mostly for commercial purposes.

Moreover, in huge houses also, people install 3 phase power to manage the load of all appliances. In short, a load of all the electric types of equipment is distributed equally among the 3 phases.

Since the current’s load is balanced, vibrations in the power are also low.

What is the 2 Phase?

The 2 phase electric system came into existence when the single-phase power system became obsolete. The 2 phase electric system also distributes power to the self-starting motors.

Both phases can handle the load of appliances below 10 kilowatts. If a higher voltage is supplied, the 2 phase meter can fail. In most cases, a two-phase system cannot accommodate more than two medium-sized air conditioners.

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The largest generators installed in the 19th century at Niagara falls operated on 2 phase power system. Two circuits are employed in 2 phase system, and three or four wires are present under 2 phase system.

In a few two-phase systems, each phase has two wires, whereas in others, each phase has one wire and one shared wire beneath the circuit.

The phases (electricity carriers) are arranged symmetrically at 90 degrees. These are becoming old-fashioned meters and are expensive power distributers.

However, one advantage is that they can supply the electricity at a constant rate like 3 phase meters.

When a 3 phase power system is connected to two transformers in such a way that 2 phase is with one transformer and a single-phase system with another transformer.

Then 3 phase meter acts as 2 phase meter and 1 phase meter on different transformers.

Main Differences Between 3 Phase and 2 Phase

  1. Mikhail Dolivo-Dobrovolsky brought the concept of the 3 phase electricity meter. On the other hand, the 2 phase meter was introduced by three expertise.
  2. The wires in a circuit of 3 phase power system are 3. On the contrary, in the case of 2 phase power system, the wires maybe three or four, depending on the circuit.
  3. The 3 phase electric meter can handle more electric load when compared to 2 phase meters.
  4. When connected to two transformers, the 3 phase can act as a 2 phase electric meter. However, a 2 phase meter can never act as 3 phase power distributer.
  5. The 3 phase electric meter is more affordable compared to 2 phase meters.
3 Phase vs 2 Phase – Whats different


  1. https://pubs.rsc.org/en/content/articlehtml/2012/cp/c1cp23367j
  2. https://pubs.rsc.org/en/content/articlehtml/2012/cp/c2cp40745k

Last Updated : 25 July, 2023

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