Altivar 312 Variable Speed Drives Page 16 Introduction

16 Altivar 312 variable speed drives Functions Functions (continued) Control mode switching Switching the command channel provides a choice of 2 control modes. Switching is enabled by: A logic input A bit in a Modbus or CANopen control word 2-wire control This function is used to control the direction of operation by means of a stay-put contact. It is enabled by means of 1 or 2 logic inputs (one or two directions of operation). This function is suitable for all non-reversing and reversing applications. Three operating modes are possible: Detection of the state of the logic inputs Detection of a change of state of the logic inputs Detection of the state of the logic inputs with forward operation having priority over reverse 3-wire control This function is used to control the operating direction and stopping by means of pulsed contacts. It is enabled by means of 2 or 3 logic inputs (1 or 2 directions of operation). It is suitable for all non-reversing and reversing applications. Forced local mode Forced local mode imposes control via the terminals or display terminal and disables all other control modes. The following references and commands are available for forced local mode: References AI1, or AI2, or AI3 and command via logic inputs Reference and command via RUN and STOP/RESET keys and the navigation button Reference and command via the remote display terminal The changeover to forced local mode is enabled by a logic input. Freewheel stop This stops the motor by resistive torque if the motor power supply is cut. A freewheel stop is achieved by: Configuring a normal stop command as a freewheel stop (on disappearance of a run command or appearance of a stop command) Enabling a logic input Fast stop This is used to achieve a braked stop with a deceleration ramp time (divided by 2 to 10) that is acceptable for the drive/motor unit without locking on an overbraking detected fault. It is used for conveyors with electrical emergency stop braking. A fast stop is achieved by: Configuring a normal stop as a fast stop (on disappearance of a run command or appearance of a stop command) By enabling a logic input DC injection stop This function is used for low speed braking of high-inertia fans, or for maintaining torque when stopping fans located in an airflow. A DC injection stop is achieved by: Configuring a normal stop as a DC injection stop (on disappearance of a run command or appearance of a stop command) Enabling a logic input The DC value and the standstill braking time are adjustable. 24 V LI1 LIx Altivar 312 control terminals LI1: forward LIx: reverse Wiring diagram for 2-wire control 24 V LI1 LI2 LIx Altivar 312 control terminals Wiring diagram for 3-wire control 1 0 f (Hz) Stop Forward Reverse t Example of 3-wire control operation

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