{"id":50,"date":"2018-06-27T13:12:29","date_gmt":"2018-06-27T17:12:29","guid":{"rendered":"https:\/\/pressbooks.bccampus.ca\/trigforelectricians\/?post_type=chapter&p=50"},"modified":"2018-12-14T15:04:38","modified_gmt":"2018-12-14T20:04:38","slug":"50","status":"publish","type":"chapter","link":"https:\/\/pressbooks.bccampus.ca\/trigforelectricians\/chapter\/50\/","title":{"raw":"Power and Impedance Triangles","rendered":"Power and Impedance Triangles"},"content":{"raw":"

What is going on here?<\/h1>\r\nThis is the point where I am going to ask you to take my hand and to trust me. \u00a0Okay, you don't have to take my hand, but you do have to trust me.\u00a0\u00a0We are going to start using some terms before totally going into the theory behind them. \u00a0I promise that we will get more in-depth into these concepts in future lessons.\r\n

Impedance triangles<\/h1>\r\nWhen dealing with DC circuits the only thing that opposes current is the resistance<\/strong> in the circuit.\r\n\r\n[caption id=\"attachment_122\" align=\"aligncenter\" width=\"300\"]\"\"<\/a> Figure 20. DC resistive circuit<\/strong>[\/caption]\r\n\r\nAs we will learn in later units, AC adds a component that opposes current as well. \u00a0This is called reactance<\/strong> and it runs 90 degrees to the circuit resistance.\u00a0\u00a0This means it is not possible to add them together arithmetically;\u00a0 it has to be done using the Pythagoras' theorem.\u00a0\u00a0When you add these two together, you get a total opposition to current flow called impedance<\/strong>.\r\n\r\n[caption id=\"attachment_123\" align=\"aligncenter\" width=\"300\"]\"\"<\/a> Figure 21. DC inductive circuit<\/strong>[\/caption]\r\n\r\nThe triangle that is created when adding the resistance to the reactance is known as an impedance triangle<\/strong>.\r\n\r\n[caption id=\"attachment_124\" align=\"aligncenter\" width=\"300\"]\"\"<\/a> Figure 22. Impedance triangle<\/strong>[\/caption]\r\n\r\nIn an impedance triangle, the resistance (r) is always on the bottom of the triangle, the reactance (x) always goes on the side and the hypotenuse is always the impedance (z).\r\n

Power triangles<\/h1>\r\nWhen dealing with a purely resistive circuit, the power being dissipated is in the form of heat or light and is measured in watts and is known as true or active power<\/strong>.\u00a0 It is a product of I2<\/sup>R.\r\n\r\n[caption id=\"attachment_125\" align=\"aligncenter\" width=\"300\"]\"\"<\/a> Figure 23. Resistive power circuit<\/strong>[\/caption]\r\n\r\nIn an AC circuit with inductance, watts are still present. \u00a0There is also a reactive power present as current passes across the reactance. \u00a0This power is called reactive power<\/strong> and is also called wattless or quadrature power<\/strong>.\u00a0 Its unit is the Vars.\r\n\r\n \r\n\r\n[caption id=\"attachment_126\" align=\"aligncenter\" width=\"300\"]\"\"<\/a> Figure 24. Inductive power circuit<\/strong>[\/caption]\r\n\r\nMuch like the impedance triangle, we can not just add the two powers together to get overall power. \u00a0They must be added using the Pythagoras' theorem.\u00a0 Their sum is equal to the apparent power<\/strong> (VA).\r\n\r\n[caption id=\"attachment_127\" align=\"aligncenter\" width=\"300\"]\"\"<\/a> Figure 25.\u00a0 Power triangle<\/strong>[\/caption]\r\n\r\nWhen calculating for reactive power, we are still able to use the power formulas.\u00a0 We just have to use them with reactance instead of resistance.\r\n