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Spare parts spare parts, the DCS control system of PLC system and the robot system spare parts,Brand advantage: Allen Bradley, BentlyNevada, ABB, Emerson Ovation, Honeywell DCS, Rockwell ICS Triplex, FOXBORO, Schneider PLC, GE Fanuc, Motorola, HIMA, TRICONEX, Prosoft etc. Various kinds of imported industrial parts

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TRICONEX 4211 pulse output card

The field exciter unit has a filter for smoothing the actual field current measurement. The filter has no influence on the PI-controller but only on the measured signal transferred to the drive software. The filter time constant should not be set too high because the same signal is also used for minimum and overcurrent supervision of the field exciter unit.The current controller of the field excitation unit is located inside the field excitation unit. Some parameters are accessible via serial communication if the current controller needs manual tuning. The current controller is a PI-type controller that has parameters for Pgain and I-time constant.Field reversal is needed when the drive has only one armature bridge (two-quadrant). This gives the possibility to change the speed direction and also to regenerate the energy back to the network. The sign of the torque reference in armature control defines the direction of the field.On a four-quadrant drive the field reference value is always positive 100% (4095). If the EMF-controller is activated, the field current is controlled but it still can never be larger than 100%.

Field direction change hysteresis 

To avoid a too sensitive field reversal function when the torque reference value is close to zero, a parameter is needed to form a hysteresis around the zero torque reference. The hysteresis is symmetrical around zero. For exampe, the hysteresis value is 80. The drive will change to reverse field when the torque reference is - 80 or smaller. Back to forward field the drive can change when the torque ref is +80 or larger. REV.REF HYST (1319) (default 80) Force field direction It is possible to force the drive to use a specified field direction. This gives the user the possibility to allow a change of field direction only when it is needed. For example, it is known when the drive must really change the direction of speed. Using the force-command makes the drive less sensitive to the value of the torque reference

Field monitoring when changing direction 

Normally the field current is compared with the minimum level and if the current falls below the limit, all the control functions are blocked and the drive goes to state RDY RUN = 0 and RDY REF = 0. During the field change the situation differs. The current can be below the minimum field level for a certain time because the field current must pass over zero. In the process of field changing the current controller and the speed controller I-part are blocked and the speed ramp output is updated by the actual speed value.The field current must change direction during a period of 2 sec, otherwise signal ACK_FEXC1_ON goes to 0 and RDYRUN and RDYREF are set to 0. Following parameters are needed to supervise the function: F1 CURR GT MIN L (1305) Defines the minimum level for the field current REV.REV HYST (1318) The sign of the torque reference defines the field direction. Actual field direction is based on comparison of field current reference and actual. The hysteresis is used in actual current measurement when field reversal acknowledge signal is produced.