![]() Therefore, interlocking, as required on electromechanical devices, is not required for variable frequency drive for ward/reverse operations. Because variable frequency drives are electronic devices, they can have only one phase rotation output at a time. For example, if a motor has to operate at three different speeds, a relay or switch contact could be made to close & send signals to separate digital inputs points that would change the motor speed to the preset value.įollowing diagram shows typical input digital connections for two-wire or three-wire control with stop, forward, reverse, & jogging functions. Each digital input may have a preset function assigned to it, such as start/stop, forward/reverse, external fault, & preset speed selections. Digital inputs are used to interface the VFD with devices such as push buttons, selector switches, relay contacts & PLC digital output modules.
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