Lenze SL - Manual (Page 42)

42 Lenze 13466147 EDBSM01 v19 EN
4 Commissioning
P25 CURRENT LIMIT
P25 sets the maximum allowable output current of the drive. The maximum setting is either 180%
or 150%, depending on whether LINE VOLTAGE SELECTION (Parameter 01) is set to HIGH or LOW.
If the load demands more current than the CURRENT LIMIT setting, the drive will reduce the output
frequency in an attempt to reduce the output current. When the overcurrent condition passes, the
drive will accelerate the motor back up to the speed setpoint.
P26 MOTOR OVERLOAD
The SCL/SCM Series is UL approved for solid state motor overload protection, and therefore does not
require a separate thermal overload relay for single motor applications. This circuit allows the drive to
deliver up to 150% current for one minute. If the overload circuit “times out”, the drive will trip into
an OVERLOAD fault (displayed as "PF"). MOTOR OVERLOAD should be set to the ratio (in percent) of
the motor current rating to the drive's output current rating to properly protect the motor.
Example: A 3 HP, 480 Vac drive with a 4.8 Amp rating is operating a 2 HP motor with a current rating
of 3.4 Amps. Dividing the motor current rating by the drive's output current rating yields 71% (3.4 /
4.8 = 0.71 = 71%), so this parameter should be set to 71%.
P27 BASE FREQUENCY
The BASE FREQUENCY determines the V/Hz ratio by setting the output frequency at which the drive
will output full voltage to the motor. In most cases, the BASE FREQUENCY should be set to match
the motor’s rated frequency.
Example: A 230 Vac, 60 Hz motor requires a V/Hz ratio of 3.83 (230 V / 60 Hz = 3.83 V/Hz) to produce
full torque. Setting the BASE FREQUENCY to 60 Hz causes the drive to output full voltage (230 Vac)
at 60 Hz, which yields the required 3.83 V/Hz. Output voltage is proportional to output frequency,
so the 3.83 V/Hz ratio is maintained from 0 - 60 Hz, allowing the motor to produce full torque from
about 2 Hz (below 2 Hz there is less torque due to slip) up to 60 Hz.
NOTE
If this parameter is changed while the drive is running, the new value will not take effect
until the drive is stopped.
P28 FIXED BOOST
FIXED BOOST increases starting torque by increasing the output voltage when operating below
half of the base frequency. For better out-of-the-box performance, SCL/SCM Series drives are
shipped with a setting that is different from the factory default of 1%. Units rated 0.33 to
1 HP (0.25 to 0.75 kW) = 5.3%, 1.5 to 2 HP (1.1 to 1.5 kW) = 4.4%, 3 HP (2.2 kW) = 3.6%, 5 HP
(4 kW) = 3.0%, 7.5 HP (5.5 kW) = 2.7%, 10 HP (7.5 kW) = 2.4%, and 15 HP (11 kW) = 2.2%.
P29 ACCELERATION BOOST
ACCELERATION BOOST helps accelerate high-inertia loads. During acceleration, the output voltage
is increased to increase motor torque. Once the motor reaches the new speed setpoint, the boost is
turned off and the output voltage returns to the normal value.