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There are several crucial factors that builders and contractors put into consideration at the time of constructing buildings. Beyond aesthetics, the need to supply the right amount of electrical energy in a building cannot be overemphasised.
However, many house owners do not understand why this is important, nor do they understand some of the terminologies and often misuse them. Knowing what phase power to use and the reason for making this choice will meet your electrical consumption needs and can significantly reduce electrical energy costs.
Basic Information About 3-Phase Power
A three-phase power alternating current (AC) is generally required for electricity delivery to data centres. It is also used for commercial and industrial buildings with heavy equipment and machinery.
The reason for this is that 3-phase power is capable of delivering more power and at a greater efficiency than when single-phase AC power is used. The single-phase AC is commonly used for most households and light commercial applications. This phase is sufficient to handle lighting and small appliances in homes.
When is it necessary to use 3-phase power?
There is often a dramatic increase in the need for electrical energy in data centres and server rooms. To this end, the ability to supply the required amounts of power is essential. It is a common practice now to pack computing systems into the same spaces where servers were once housed. The interesting thing is that they only use a fraction of the electrical power that is required by these computers and networks used by those servers.
Not many years ago, only one IT rack containing up to 10 servers would draw a maximum of five kilowatts (kW) of power. It will be surprising to learn that the same rack can now house dozens of servers that would draw 20 or 30 kW altogether. With all these changes, you want to pay attention to the importance of efficiency in your electrical supply.
This is so because even a slight increase in percentage improvement of your power consumption can significantly reduce electricity costs. The issue of wiring is also worthy of mention here. For example, if you consider a 15 kW rack and a single phase is used at 120 volts AC power, you would require 125 amps to power this rack. A wire with a diameter of almost one-quarter of an inch or 3.1 centimetres (AWG 4) will be required.
This type of wire is too thick and difficult to work with and could also be expensive. If you used a 3-phase power for the same 15 kW rack, you would need three wires supplying 42 amps (AWG 10). This is a fraction of the size. Moreover, each of the wires is less than a tenth of an inch or 2.5 millimetres in diameter.
Understanding How Single-Phase AC Power Works
A single-phase AC power uses a three-wire delivery system. This system consists of a neutral wire, a "hot" wire, and a ground. When AC power is used, the voltage or power current reverses from time to time. Electrical current flows one way through the hot wire that gives power to the load and goes the other way on the neutral wire.
There is a complete power cycle during a 360-degree phase change, and during this period, the voltage reverses itself up to 50 to 60 times each second. The number of times the reversals are made depends on the system used in the region you find yourself in.
In North America, for example, reverses are made 60 times, referred to as 60 hertz (Hz). One vital thing to take note of is that the two current-carrying wires are always situated 180 degrees apart.
Understanding How The 3-Phase Power AC Works
As it may be inferred from the name, a 3-phase power system supplies three separate currents, and each of these is separated by one-third of the amount of time required to complete a whole cycle. With a 3-phase power system, the currents are separated by 120 degrees.
With this type of power system, you can expect that the complete amount of power generated by all three currents will remain constant. Therefore, there are no cyclical peaks and valleys, as you will find in the case of a single-phase power system.
This has been factored into designing computers and several types of motors used in heavy machinery. They can draw a constant stream of power this way instead of accounting for the difference observed in single-phase AC power. With this approach, less energy is used.
The Benefits Of 3-Phase Power
Can accommodate twice the amount of power as single phase
Several benefits come with the use of a 3-phase power system. One such is its ability to deliver close to twice the power a single-phase system would give without needing twice the number of wires. You should remember that the system does not provide three times as much energy as one may be led to misbelieve with the name because, in reality, only one hot line is connected to another.
Some maths may be required to understand how 3-phase can deliver more power. A single-phase power works by the formula Power = Voltage (V) x Current (I) x Power Factor (PF). Assuming the load on the circuit is resistive only, then the PF is one, reducing this formula to P = V x I. In a situation where a 120-volt circuit supports 20 amps, the power generated will equal 2,400 watts.
Where a 3-phase circuit is used, you will write the formula as Power = Voltage (V) x Current (I) x Power Factor (PF) x square root of three. Assuming that the load on this circuit is resistive, the PF is just one. With this, the formula gets reduced to P = V x I x square root of three. If a 120-volt 3-phase circuit is used, with each phase supporting 20 amps, the formula stands at 120 Volts x 20 Amps x 1.732 = 4,157 watts. In this manner, a three-phase power can deliver close to double that of a single-phase system.
The capacity is beneficial when powering racks of IT gear
The kind of capacity this type of phase power has is useful where there is a need to power racks of IT gear. Whereas allocating a single-phase power to one rack was the usual practice.
With the increase in the densities of IT racks, this route became less practicable. The conductors, cabling, and sockets get bigger and more expensive, hence increasingly more brutal to work with.
Allows for the use of cheaper cabling and other components
When 3-phase power is directly delivered to the server rack, it becomes possible to use less expensive cabling and other necessary components. This does not compromise the delivery of more power as expected from the system. However, it becomes essential to pay attention to the load of each of the circuits so that you may maintain a balance and circuit capacity is not exceeded.
Faults that occur on one line don't affect the other lines
Faults can occur without warning in any of these power systems. An error in a single phase could get the entire system shut down. However, a mistake with one of the lines in a three-phase power system would not get the whole system shut down. The other two lines can carry on with the provision of power.
You can operate single-phase machinery and appliances
If you have a 1-phase machine, you can get a single-phase supply to power it from a three-phase supply. However, operating a three-phase machine on a single-phase supply voltage is impossible.
What To Do To Upgrade To 3-Phase Power
You may soon realise that upgrading to a 3-phase power system would be better. One of the things that can be responsible for this is the installation of appliances or machines in your home that require large amounts of electrical power.
This should be a relatively straightforward task to do, although it requires the expertise of professionals. What is advisable to do is to contact certified local electricians that can get the job done on time for you and without any fear of mishap.
