{"id":6978,"date":"2021-05-03T14:47:55","date_gmt":"2021-05-03T14:47:55","guid":{"rendered":"https:\/\/powerside.com\/?p=6978"},"modified":"2023-02-21T21:35:01","modified_gmt":"2023-02-21T21:35:01","slug":"what-is-power-factor","status":"publish","type":"post","link":"https:\/\/modomodostage.com\/_client\/PWS\/PWS101\/what-is-power-factor\/","title":{"rendered":"What is Power Factor?"},"content":{"rendered":"\n

Imagine ordering a meal at a new restaurant in town. You sit down and select something from the menu, and the waiter brings you a plate of food. If the meal is excellent and you eat everything, this is an efficient way of satisfying your hunger. However, it becomes less efficient if you do not like some of the food or if it is inedible. This part of the meal is still prepared, cooked, and served to you, but it is ultimately returned to the kitchen uneaten. You could calculate the proportion of the food that you ate compared to the size of the overall meal, which would tell you how efficient this restaurant is at meeting your needs.<\/p>\n\n\n\n

More generally speaking, if you consider the proportion of any consumable that meets a need, compared to the proportion that is instead returned to the source, unused, you have a measure of how efficiently a system meets that need. When you apply this to an electrical circuit, where the consumable is electrical power, the efficiency measure is the power factor<\/a>.<\/p>\n\n\n\n

An efficient electric circuit is one in which the load uses most of the\nsupplied power to do work. Whereas an inefficient electrical circuit is one that draws electrical\npower, but uses a part of it to do things that are not productive. During each\nalternating current cycle, the circuit draws that power from and returns it to\nthe power source. The power\nfactor is the ratio of the electrical power that the load uses compared\nto the overall amount of power supplied to the circuit. This calculation tells\nyou how efficient the electrical\ncircuit is at supplying power to do work.<\/p>\n\n\n\n

Know your Powers<\/strong><\/h2>\n\n\n\n

Active power<\/strong><\/h3>\n\n\n\n

Active\npower is the name given\nto the power consumed by an electrical circuit doing something useful, like powering\nstreet lights or running a production line. The measurement of active power is watts<\/a> (W), or multiples thereof, such as\nkilowatts (kW) and megawatts (MW). A device that runs on electrical power has a\nrating based on the active\npower that it consumes, such as a 60W light bulb or a 500kW arc furnace.<\/p>\n\n\n\n

Reactive power<\/strong><\/h3>\n\n\n\n

Reactive\npower is the term used\nto describe the power drawn by an electrical circuit to do things that are not productive like\ncharging a capacitor or creating the magnetic field in an induction motor. Its\nunit of measurement is volt-ampere reactive<\/a> (VAR). In an electrical circuit,\ndevices producing or consuming reactive\npower, such as shunt reactors and capacitors, have a VAR rating.<\/p>\n\n\n\n

Apparent power<\/strong><\/h3>\n\n\n\n

Apparent\npower is the total\npower passing through an electrical\ncircuit, both active and reactive. It is a significant value to consider\nwhen designing and rating an electrical circuit. The measurement of apparent power is volt-ampere<\/a> (VA). You will often see devices\nused to generate or transform electrical power rated in kVA, or MVA. Examples\nmay include a 50kVA transformer or a 1000kVA diesel generator.<\/p>\n\n\n\n

How\ndo you measure power factor?<\/strong><\/h2>\n\n\n\n

You can connect monitoring devices to critical locations in an electrical circuit to measure voltage and current. These locations include generator outputs, transformer connections, and large, intermittent, or unpredictable loads. Such a monitoring device can use the measured voltage and current values to calculate the active, reactive, apparent power, and power factor. More advanced devices such as the PQube 3<\/a> power analyzer, can record this data over time and generate regular reports.<\/p>\n\n\n\n

Leading\nand lagging power factor<\/strong><\/h2>\n\n\n\n

Returning to the restaurant, in a perfect world, the waiter will serve the\nmain course and the side dishes simultaneously. This is the most efficient method\nof delivering your meal. If the side dishes arrive at your table very early or\nlate, it will reduce how satisfied you are with the service. The earlier the side\ndishes lead, or the later they lag behind the main course, the less acceptable\nthe situation becomes. In much the same way, the alternating current in an electrical circuit\ncan lead, lag, or match the voltage, and this has an impact on the power factor.<\/p>\n\n\n\n

In an ideal electrical\ncircuit, where the impedance of the load is only resistive, the current\nand voltage pass through the load at the same time. When this occurs, the apparent power is equal\nto the active power\nand the power factor is\none. This is also known as unity power factor. Power\nfactor is also sometimes described as either leading or lagging. With a\nleading power factor,\nthe current leads the voltage, and the circuit is generating reactive power. This is due\nto the impedance of the electrical\ncircuit being mainly capacitive, such as with underground cables. With a\nlagging power factor,\nthe opposite is the case, the current lags the voltage. This electrical circuit is\nconsuming reactive power,\ncaused by a predominantly inductive load, such as an induction motor.<\/p>\n\n\n\n

In summary, power\nfactor is simply expressed as the ratio of active power to apparent power. The closer this ratio is to one,\nthe more of the apparent\npower is active\npower supplied to the load, and the more efficient the electrical circuit\nis. The more the power factor\nleads or lags, the larger the deviation from unity power factor, and the greater the power\nrequirements for the electrical\ncircuit.<\/p>\n\n\n\n

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