Lenze MC3000 Series - Manual (Page 50)

46 13435743_EDBM301_v14 .0
NOTE
The ability to accelerate a given load at a particular rate is limited
by the output power capability of the drive/motor combination . The
acceleration of high-inertia and high-friction loads may be affected by
the current limiting characteristics of the drive . Refer to Parameters: 16 -
CURRENT, 19 - FX BOOST, and 20 - AC BOOST for more information .
9 DECEL (DECELERATION TIME)
DECEL sets the deceleration rate for all speed reference sources . The DECEL setting is
the time to decelerate from BASE FREQUENCY to 0 Hz . As with Parameter 8 - ACCEL,
this is a linear function . If the drive is set to coast to a stop, DECEL will have no effect when
a STOP command is given . The range of adjustment for DECEL depends on horsepower,
voltage, and whether Dynamic Braking (DB) is being used . Refer to the table below:
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 - 30 HP 25 - 60 HP 10 - 20 HP 1 .0 - 3600 SEC 0 .2 - 3600 SEC
---- ---- 25 - 60 HP 2 .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 .