WEG CFW300 V1.3X, Programming Manual

Page: 83 / 157

Functions Common to All the Control Modes
CFW300 | 11-3
11
P105 - 1
st
/ 2
nd
Ramp Selection
Adjustable
Range:
0 = 1
st
Ramp
1 = 2
nd
Ramp
2 = DIx
3 = Serial/USB
4 = Reserved
5 = CO/DN/DP
6 = SoftPLC
Factory
Setting:
0
Properties:
Description:
It defines the origin source of the command to select between the first and second Ramp.
Note: Parameter P680 (Logical Status) indicates if the 2
nd
Ramp is active or not. For further information on this
parameter, refer to Section 7.3 CONTROL WORD AND INVERTER STATUS on page 7-11 .
11.2 DC LINK VOLTAGE AND OUTPUT CURRENT LIMITATION
The DC link voltage and output current limitation are protection functions of the inverter which act on the ramp
control, aiming at containing the rise of voltage on the DC link and of the output current. In this way, the following of
the reference by the ramp is blocked and the output frequency follows the Emergency Ramp for a preset safety
value.
When the DC link voltage is too high, the inverter may freeze the deceleration ramp. On the other hand, when
the output current is too high, the inverter may decelerate or freeze the acceleration ramp in order to reduce this
current. Those actions prevent the occurrence of faults F022 and F070, respectively.
Both protections normally occur at different moments of the inverter operation, but in case of occurrence at the
same time, by definition, the DC link limitation has higher priority than the output current limitation.
The voltage limitation on the DC link during braking actuates limiting the braking power and torque, so as to prevent
the shutting down of the inverter for overvoltage (F022). This situation often occurs when a load with high moment
of inertia is decelerated or when short deceleration time is programmed.
11.2.1 DC Link Voltage Limitation by "Ramp Hold" P150 = 0 or 2
„
It has effect during deceleration only.
„
Actuation: when the DC link voltage reaches the level set in P151, a command is sent to the "ramp" block, which
inhibits the motor frequency variation according to
Figure 9.1 on page 9-2 and Figure 10.1 on page 10-2 .
„
Use recommended in the drive of loads with high moment of inertia referred to the motor shaft or loads that
require short deceleration ramps.
11.2.2 DC Link Voltage Limitation by "Accelerate Ramp" P150 = 1 or 3
„
It has effect in any situation, regardless the motor frequency condition: accelerating, decelerating or constant
frequency.
„
Actuation: when the DC link voltage reaches the level set in P151, a command is sent to the "ramp" block to
accelerate the motor.
„
Use recommended for the drive of loads that require braking torques at constant frequency in the inverter
output. For example, the drive of loads with eccentric shaft as in sucker rod pumps; another application is the
handling of loads with balance like in the translation in overhead cranes.