{"id":117,"date":"2020-01-13T13:41:51","date_gmt":"2020-01-13T18:41:51","guid":{"rendered":"https:\/\/opentextbc.ca\/basicmotorcontrol\/chapter\/motor-lead-connections\/"},"modified":"2022-02-08T14:31:35","modified_gmt":"2022-02-08T19:31:35","slug":"motor-lead-connections","status":"publish","type":"chapter","link":"https:\/\/opentextbc.ca\/basicmotorcontrol\/chapter\/motor-lead-connections\/","title":{"raw":"Motor-Lead Connections","rendered":"Motor-Lead Connections"},"content":{"raw":"Three-phase motors use coils of wire to create magnetic fields and produce rotation.\r\n\r\nStandard 3-phase motors use six individual coils, two for each phase. The internal construction and connection of these coils inside of the motor is predetermined when the motor is manufactured. There are two classes of 3-phase motors: Wye and Delta.\r\n\r\n[caption id=\"attachment_116\" align=\"alignnone\" width=\"1024\"]\"\" Wye and Delta configuration[\/caption]\r\n\r\nThree-phase motors are also constructed to operate at two different [pb_glossary id=\"219\"]voltages[\/pb_glossary],\u00a0and so the coils can be connected in either their high-voltage or low-voltage configurations.\r\n\r\nIn the high-voltage configuration, the two coils of each phase are connected in [pb_glossary id=\"269\"]series[\/pb_glossary]\u00a0with each other so that the higher value of supply voltage is split equally between them and rated current is drawn through each winding.\r\n\r\nIn the low-voltage configuration, the two coils of each phase are connected in\u00a0[pb_glossary id=\"268\"]parallel[\/pb_glossary]\u00a0with each other so that the lower value of supply voltage is shared equally between the coils and rated current is drawn through each winding.\r\n\r\nNote that the low-voltage connection will necessarily need to draw twice as much current from the source as the high-voltage connection. Most motors will list two values of voltage and current on their nameplates. It is important to size [pb_glossary id=\"227\"]motor starters[\/pb_glossary] and their [pb_glossary id=\"241\"]overload relays[\/pb_glossary] based on the expected value of current that is to be drawn by the motor at the voltage it is used at.\r\n\r\nEach of the six individual coils has two leads supplying it, for a total of twelve leads in total. In both the Wye and Delta configurations, three of these leads are connected internally, and so only nine leads are brought out of the motor for connection. These leads are numbered 1\u20139, and in both Wye and Delta follow a standard numbering convention: starting at the top of the diagram with wire number 1, draw an inwardly descending spiral from each connection point, ascending to the next number at each step.\r\n\r\nDepending upon the internal construction of the motor, these leads can be hooked up in one of four ways: High- or low-voltage Wye, or high- or low-voltage Delta\r\n

Identifying Wye or Delta with an Ohmmeter<\/h1>\r\nIt sometimes becomes necessary to test or confirm the configuration of a motor before final connection. If a Wye wound motor is connected as a Delta wound motor or vice versa, the motor will not operate properly.\r\n\r\nConsider this situation: You have nine leads coming from a motor, but no indication of whether its Wye or Delta wound. By using an [pb_glossary id=\"255\"]ohmmeter[\/pb_glossary] to do a simple continuity check, you can determine the construction type of the motor.\r\n\r\nIf it is Wye wound, each of wires 1, 2, and 3 should only have continuity with one other lead (4, 5 and 6 respectively). The three leads without continuity to wires 1, 2, and 3 should all have continuity with each other.\r\n\r\n[caption id=\"attachment_116\" align=\"aligncenter\" width=\"1024\"]\"\" Wye motor connections[\/caption]\r\n\r\nIf it is Delta wound, each of wires 1, 2, and 3 should have continuity with two other leads:\r\n