VFD Parameters Programming / Setting

The main VFD program is contained in the processor's firmware & not normally accessible to the variable frequency drive user. A parameter is a variable associated with the operation of the VFD that can be programmed or adjusted. Parameters provide a degree of adjustment so that the user can customize the VFD to suit specific motor & driven equipment requirements. The number of parameters can range from 50, for small basic VFDs, to over 200 for larger, more complex VFDs. Some variable frequency drives provide upload/download & parameter copy capability. Common adjustable parameters include the following:

• Preset speeds
• Minimum & maximum speeds
• Acceleration & deceleration rates
• Two- & three-wire remote control modes
• Stop modes: ramp, coast, DC injection
• Automatic torque boost
• Current limit
• Configurable input jog
• V/Hz settings
• Carrier frequency
• Program password

Variable frequency drives come with factory default settings for most parameters that are more conservative in nature. The default value settings simplify the start-up procedure.

However, parameters for motor nameplate data are not factory-set (unless a matched VFD & motor has been purchased) & must be entered in the field. In general there are three types of parameters:

1. Tunable on the l y - Parameters can be adjusted or changed while the VFD is running or stopped. Response Original speed Desired new speed Desired speed (setpoint) Actual speed Deviation (error) PID controller output Proportional circuit Integral circuit Derivative circuit.
2. Configurable - Parameters can be adjusted or changed only while the VFD is stopped.
3. Read only - Parameters cannot be adjusted.

The VFD display shows either a parameter number or a parameter value. The VFD's parameter menu outlines what the parameter number represents & what numerical selections or options for the parameter are available. Parameter menu formats vary between make & model. This VFD has two kinds of parameters: program parameters (P-00 through P-64), which configure the VFD operation & display parameters (d-00 through d-64), which display information. Examples of program parameters include:

• P-00 minimum speed - Use this parameter to set the lowest frequency the VFD will output. Default setting is 0.
• P-01 maximum speed - Use this parameter to set the highest frequency the VFD will output. Default set ting is 60 Hz.
• P-02 motor overload current - Set this parameter to the motor nameplate full-load ampere rating. Default setting is 100 percent of the rated VFD current.
• P-30 acceleration time - Use this parameter to define the time it will take the VFD to ramp up from 0 Hz to maximum speed. Default setting is 5.0 seconds.

Examples of display parameters include:

• d-00 command frequency - This parameter represents the frequency that the VFD is commanded to output.
• d-01 output frequency - This parameter represents the output frequency at the motor terminals.
• d-02 output current - This parameter represents the motor current.
• d-03 bus voltage - This parameter represents the DC bus voltage level.