8400 StateLine C | Reference manual
Motor control (MCTRL)
V/f characteristic control (VFCplus)
130
L
Firmware
≤
11.00 - DMS 8.0 EN - 10/2011
5.4.2.2
Defining current limits (Imax controller)
The V/f characteristic control (VFCplus) and the V/f control (V encoder) operating
modes are provided with a current limitation control which is decisive for the dynamic
behaviour under load and counteracts exceedance of the maximum current in motor or
generator mode. This current limitation control is called I
max
control.
The efficiency (motor current) measured by the I
max
control is compared with the
current limit value for motor load set in
C00022
and the current limit value for
generator load set in
C00023
.
If the current limit values are exceeded, the controller changes its dynamic behaviour.
Motor overload during acceleration
The controller prolongs the acceleration ramp to keep the current on or below the current
limit.
Generator overload during deceleration
The controller prolongs the deceleration ramp to keep the current on or below the current
limit.
Increasing load with constant speed
If the motor current limit value is reached:
– The controller reduces the effective speed setpoint until a stable working point is set
or an effective speed setpoint of 0 rpm is reached.
– If the load is reduced, the controller increases the effective speed setpoint until the
setpoint speed is reached or the load reaches the current limit value again.
When the generator current limit value is reached:
– The controller increases the effective speed setpoint until a stable working point is
set or the maximally permissible speed (
C00909
) or output frequency is reached
(
C000910
).
– If the load is reduced, the controller reduces the effective speed setpoint until the
setpoint speed is reached or the load reaches the current limit value again.
If a sudden load is built up at the motor shaft (e.g. drive is blocked), the overcurrent
disconnection may respond (fault message OC1 or OC11).
Phone: 800.894.0412 - Fax: 888.723.4773 - Web: www.clrwtr.com - Email: info@clrwtr.com
