Lenze MCH Series - Manual (Page 53)

13435744_EDBMH01_v13 49
DECELERATION LIMITS
HORSEPOWER / VOLTAGE RATING RANGE OF ADJUSTMENT
240 / 200 Vac 480 / 400 Vac 590 / 480 Vac WITHOUT DB WITH DB
(NOTE 1) (NOTE 2)
0.25 - 7.5 HP 1 - 7.5 HP ---- 0.3 - 3600 SEC 0.1 - 3600 SEC
10 - 15 HP 10 - 20 HP 1 - 7.5 HP 0.5 - 3600 SEC 0.1 - 3600 SEC
20 - 60 HP 25 - 60 HP 10 - 20 HP 1.0 - 3600 SEC 0.2 - 3600 SEC
---- 75 - 100 HP 25 - 60 HP 2.0 - 3600 SEC 0.2 - 3600 SEC
---- 125 - 250 HP 75 - 200 HP 4.0 - 3600 SEC 0.2 - 3600 SEC
NOTE 1: 240/120 Vac units have the same limits as 240/200 Vac units.
NOTE 2: This parameter can be set as low as the value shown in the WITH DB column.
However, the value shown in the WITHOUT DB column is the operational
limit of a drive without dynamic braking. For example, DECEL can be set as
low as 0.1 seconds on a 10 HP, 480 Vac drive without dynamic braking, but
the actual minimum deceleration time would be 0.5 seconds
If an attempt is made to decelerate a high-inertia load too quickly, the motor will
regenerate voltage back into the drive. This will cause the DC bus voltage to rise, which
can result in a HI VOLTS fault. In order to prevent faulting, the drive will enter DECEL
FREEZE, which halts the deceleration until the DC bus voltage returns to a normal
level. The drive will then begin to decelerate again, and if necessary, will enter DECEL
FREEZE repeatedly to avoid faulting. If a very short deceleration time is programmed,
DECEL FREEZE may not be able to compensate fast enough, resulting in a HI VOLTS
fault.
In applications where very short deceleration times are required on high-inertia loads,
dynamic braking may be required. Consult the factory for more information on the
Dynamic Braking option.
10
MINIMUM FREQ
This parameter defines the lower limit of the drive’s speed range. MINIMUM FREQ is
used in conjunction with MAXIMUM FREQ (Parameter 11) to define the operating range
of the drive.
If MINIMUM FREQ is set to a value above 0.0 Hz, the drive will ramp up from 0.0 Hz
when given a start command. Once running, however, the drive will not operate below
the MINIMUM FREQ setting unless the rotation is changed, or a stop command is
issued and the drive is programmed to ramp to a stop.
If MINIMUM FREQ is set to 0.0 Hz, the drive may be operated in ZERO SPEED mode
(drive is in RUN state, but there is no output to the motor). ZERO SPEED operation can
be used in applications requiring the ability to start and stop the drive using only the
selected speed reference. The drive will start when the speed reference is raised above
0 VDC or 4 mA, and it will stop when the reference is lowered to 0 VDC or 4 mA. Note
that the drive must be initially started using one of the normal start commands (keypad
or terminal strip).