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Each VFD channel has its own separate and independent sub menu. The following assumes that VFD2
is moved between the two tick marks and the NEXT key is pressed to display the following configura-
tion menu.
Explanation of VFD parameters:
2.
User selects name of VFD. The VFD must be named in order to be usable. The default is UNUSED.
a.The list of names available is the same as the list available for servo motors. It is required that at
least one of the servos be named AIR and the AIR servo is considered the “master/lead” drive,
when a VFD is not used in a profile. If a VFD is used in a profile, the FUEL/GAS/OIL servo
becomes the “master/lead” drive. A VFD is never the master/lead drive and the VFD name will
not impact this rule.
3.
The method for profile assignment for VFD's is the same as for servo motors.
a. ASSIGNMENT set to a non-zero value prevents the VFD channel from being used as anything
but UNUSED in ANALOG OUT SETUP sub menu.
4.
DISPLAY FORMAT is used to select the method of feedback used from the VFD. Two methods of
feedback can be selected, 4-20 mA or encoder. CNTS and PERCENT FULL SCALE are dependent on
4-20 mA from the VFD. Encoder counts is dependent on the use of an encoder. CNTS is the default
and has a range of 0 - 1000 and is derived from the 4-20 mA feedback.%FS translates the 4-20 mA to a
scale ranging from 0 - 100.0%. The scale for encoder counts is dependent on the encoder used.
a. Total encoder count is determined by the encoder's counts per revolution specification and
motor's maximum revolutions per minute, RPM. The allowable range is 300 to 5000 with a
default of 1000. The user should refer to the following rule to determine the encoder pulses per
second.
Max Motor RPM * Pulses per Revolution = encoder pulses per second
60
b. The system will then use this number to scale the counts to a value of 1000. Actual encoder
pulses per second can be found in the INFO SCREEN.
5.
RUN MODE gives the user the option of using the internal PPC4000 PID (preferred) to control the
VFD position or using the internal VFD drive's PID to control the VFD setpoint. The options are
AUTO (default) and MANUAL.
6.
In AUTO mode, gain and integral terms are used by the VFD plug-in board to control the setpoint of
the VFD. The VFD setpoint is the position of the VFD as commanded by the PPC4000. The goal
would be to have little difference between the VFD commanded signal (setpoint) and feedback signal.
a. Gain is the amplification of the error signal. This error signal is the deviation between feedback
and control. A high gain can result in unstable operation and cause overshoot. The range is 1.0%
to 100% with an increment of 0.1% and a default of 1.0%.
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