CERUS CI-007-P2, Installation, Programming Operation, & Maintenance Manual

Page: 87 / 137

Chapter 6 - Parameter Description
6-20
FG2 InertiaRate
46 10
FG2 RPM Scale
47 100 %
FG2 PWM Select
49 Normal
FG2 Safety Time
50 100.0 sec FG2 Safety Gain
51 20
for internal calculations for accurate speed control
in Slip Compensation and Sensorless modes. The
default value is set based on standard industrial
motor parameters and the capacity of the VFD. If
motor name plate does not have No Load rating, it
can be determined by running motor without load
on the shaft. If it is difficult to run the motor with
disconnected load, set FG2-44 for 35-40% of
SET-03 Motor FLA.
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The FG2-46 Inertia
Rate value is used by
VFD for internal speed control calculations for
different modes. The higher load inertia, the smaller
this number should be.
)/3+ F
The FG2-47 parameter
sets the scaling factor
for RPM display. This parameter can be used to
show RPM of the gearbox output shaft instead of
the motor shaft.
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The FG2-49 parameter
has two selections:
Normal and Low Leakage modes.
Normal - The VFD increases the carrier frequency
from minimum to SET-06 value during start.
Low Leakage - The VFD will automatically
decrease the carrier frequency to decrease leakage
current. If SET-06 is set below 2kHz and FG2-49 is
set to Low Leakage, the SET-06 Carrier Frequency
will be changed to 2kHz in order to provide proper
control range for this feature.
)7*6 7 + > ! !
FG2-50 and FG2-51 will be available when FG1-28
Safety Stop is set to Yes.
Adjust FG2-50 to a time value that is required for
the load to coast stop.
FG2-51 is an output voltage decreasing rate during
safety stop.
)0*A0.+ 1 ! " 6 %'
'! !-6 F ! F -
The FG2-60 Control Mode parameter has three
selections: V/F, Slip Compensation and Sensorless.
6.4.1 V/F (Voltage/Frequency) control
mode
The control mode parameter FG2-60 is set to V/F
mode by default which changes output voltage
corresponding to output frequency based on V/F
pattern selected in parameter FG1-40. This mode
uses standard industrial motor parameters for
internal calculations and provides simple, stable
and reliable control for most of the motors in
HVAC and pump applications.
6.4.2 Slip Compensation control mode
Set FG2-60 to "Slip compen" to enable Slip
Compensation control. This mode is mostly used in
heavy load applications when constant speed is
required. The motor usually decreases speed when
load on the shaft increases. The VFD monitors
motor current, calculates approximate speed drop,
and compensates it by increasing the speed
reference in the range of motor slip set in parameter
FG2-42. This control provides a constant motor
speed regardless of the load change.
6.4.3 Sensorless control mode
Set FG2-60 to "Sensorless" to enable Sensorless
vector control. The Sensorless control mode
provides better torque control at low speeds, load
fluctuation compensation, and better response on
rapid load changes. It is required to perform Auto-
Tuning before starting Sensorless control in order
to provide stable motor control in this mode. The
Auto-Tuning operation does not turn the motor
shaft and can be performed without disconnecting
the load from the motor. During Auto-Tuning the
VFD sends different types of pulses to the motor
windings and calculates required motor parameters.
Then it stores these parameters in memory and uses
them for calculations to provide more precise
control for the motor. It is recommended to use this
mode instead of V/F if motor draws higher than
FLA current at full speed with nominal load or
speed control at higher speeds is unstable. The no-
load motor current parameter is used in Sensorless
control calculations and should be set manually in
parameter FG2-44.
FG2 ControlMode
60 V/F FG2 Auto Tuning
61 No
FG2 %Rs
62 4.00 % FG2 %Lsigma
63 12.00 %