Control Loops 5-5
DC590+ Series DC Digital Drive
Field Control
Set-Up Notes
Use the field AUTOTUNE facility to tune the field current control loop.
Initial Conditions
1. Main contactor open, i.e. no Start/Run signal at terminal C3.
2. Set the AUTOTUNE parameter to OFF.
3. Program Stop (terminal B8) and Coast Stop (terminal B9) should be high, i.e. 24V.
4. The motor should be stationary.
Caution
Never perform a field autotune if the motor is turning above base speed, since this will generate armature voltages
that can overvoltage the armature circuit.
Performing an Autotune
1. Set the AUTOTUNE parameter to FIELD.
2. Close the main contactor, i.e. Start/run signal to terminal C3.
3. Energise the Enable terminal (C5).
The Autotune sequence is initiated. When complete (after approximately 5 seconds), the main contactor is opened signalling the end of the sequence
and the AUTOTUNE parameter is reset to OFF.
4. Perform a PARAMETER SAVE now. Refer to Chapter 6: "The Keypad - Saving Your Application".
Autotune Failed?
The AUTOTUNE ERROR message may result if:
¾ The field terminals are open-circuit or short-circuit.
¾ More than 180% or less than 20% field voltage is required to drive the current configured in the FIELD CURRENT parameter.
¾ The natural field time-constant is greater than 5 seconds.
In these cases, a manual tuning process will be required, much like the manual tuning of the armature current loop. With manual tuning, one
convenient method of producing field current demand steps is to set the field demand (SETPOINT) to 50% and then use the drive enable to move to
and from the 'quench' and 'standby' modes to create transients. Monitor the field current at control board test-point IF, scaled 4V = 100% rated field
current.
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