{"id":167,"date":"2020-01-27T15:53:02","date_gmt":"2020-01-27T20:53:02","guid":{"rendered":"https:\/\/opentextbc.ca\/basicmotorcontrol\/chapter\/timer-circuits-overview\/"},"modified":"2020-08-20T12:23:19","modified_gmt":"2020-08-20T16:23:19","slug":"timer-circuits-overview","status":"publish","type":"chapter","link":"https:\/\/opentextbc.ca\/basicmotorcontrol\/chapter\/timer-circuits-overview\/","title":{"raw":"Timer Circuits Overview","rendered":"Timer Circuits Overview"},"content":{"raw":"So far all the circuits we have been looking at have all used instantaneous contacts. Both [pb_glossary id=\"227\"]motor starters[\/pb_glossary] and [pb_glossary id=\"262\"]control relays[\/pb_glossary] have [pb_glossary id=\"1098\"]contacts[\/pb_glossary] that change their state as soon as the coil is energized.\n\nIf a circuit requires some sort of delay in timing action, perhaps for sequence control or safety purposes, then timing relays can be used to provide this function. For example, a conveyor belt system might have several motors installed in it. Starting each motor at the same time could induce a very large [pb_glossary id=\"207\"]inrush current[\/pb_glossary] on the system. One way to minimize the effects of these inrush currents is to stagger the starting of the motors with on-delay timers.\n\nIf this same conveyor belt system was designed so that each segment fed onto the next and at the end of the work day each conveyor segment had to be cleared, using off-delay timers would allow the circuit to be arranged so that after pressing a single stop button, each of the motors continued to run for a limited time until all product was cleared off them.\n\nTimers can also be used to provide both [pb_glossary id=\"226\"]plugging[\/pb_glossary] and [pb_glossary id=\"231\"]anti-plugging[\/pb_glossary] for certain circuits. Indeed the range of application for timers is nearly limitless.","rendered":"

So far all the circuits we have been looking at have all used instantaneous contacts. Both motor starters<\/a> and control relays<\/a> have contacts that change their state as soon as the coil is energized.<\/p>\n

If a circuit requires some sort of delay in timing action, perhaps for sequence control or safety purposes, then timing relays can be used to provide this function. For example, a conveyor belt system might have several motors installed in it. Starting each motor at the same time could induce a very large inrush current<\/a> on the system. One way to minimize the effects of these inrush currents is to stagger the starting of the motors with on-delay timers.<\/p>\n

If this same conveyor belt system was designed so that each segment fed onto the next and at the end of the work day each conveyor segment had to be cleared, using off-delay timers would allow the circuit to be arranged so that after pressing a single stop button, each of the motors continued to run for a limited time until all product was cleared off them.<\/p>\n

Timers can also be used to provide both plugging<\/a> and anti-plugging<\/a> for certain circuits. Indeed the range of application for timers is nearly limitless.<\/p>\n

definition<\/span>