Power optimization
Group 68 Power optimization
The Range/Unit column in the table below shows the allowable parameter values. The text following the table explains the parameters in detail.
Parameter
Range/unit
Description
1 POWOP SELECT
Power optimization select 2 BASE SPEED
TRUE; FALSE
Base speed
Powop autotune select 4 INERTIA TOTAL UP
3 POWOP AUTOTUNE SEL
True ; False
Inertia total upwards 5 INERTIA TOTAL DWN
0.00 ... 100.00 KGM2
Inertia total downwards 6 TQLIM UP
0.00 ... 100.00 KGM2
Powop torque limit upwards 7 TQLIM DWN
Powop torque limit downwards 8 POWOP RESET LEV
Power optimization reset level 9 T MAX
Motor maximum torque capacity 10 LOAD TORQ FILT TC
Load torque signal filter time constant 11 SLACK ROPE TQ LEV
0 … 32000 ms
Slack rope torque indication level 12 LOADCORR FACT UP
Loadcorrection factor upwards 13 LOADCORR FACT DWN
Loadcorrection factor downwards 14 RAMPE RATE POWOP
Ramp rate for the power optimization area.
15 RAMP CHANGE SPEED
Speeed at which the ramp rate will change.
1 POWOP SELECT
TRUE Power optimization is active (only used on hoist drive).
FALSE Power optimization not active.
2 BASE SPEED
Breakpoint for Power optimization calculation. Set in percent of parameter 69.1 SPEED SCALING RPM. Above this speed constant power, corresponding to level set in parameters 68.6 & 68.7 , is obtained.
Normally the speed where field weakening starts and the available RMS power of the motor is constant. Full load torque possible for mechanics up to this speed.
3 POWOP AUTOTUNE SEL
TRUE Activates the tuning.
Note: The parameter is reset to FALSE after each calculated Total inertia value. The value of the inertia can be read in actual signal no.1.24 TOTAL INERTIA An average value after running 2-3 times in each direction should than be entered
to parameters INERTIA TOTAL UP and INERTIA TOTAL DWN respectively FALSE
Autotune mode not active
4 INERTIA TOTAL UP
Total inertia measured in upwards direction NOTE: Calculation of Inertia parameters has changed compared to previous sw
versions (crane application sw version ACAA7020 and earlier). For upgrading a drive with earlier sw versions use the following rescaling formula for Inertia parameters 68.4 and 68.5 .
Inertia(new) = ((8363*Pnom) / (nmax * nnom)) * Inertia(old). Where: - "Pnom" is the value of parameter 99.9 MOTOR NOM POWER. - "nmax" is the value of parameter 69.1 SPEED SCALING RPM - "nnom" is the value of parameter 99.8 MOTOR NOM SPEED.
5 INERTIA TOTAL DWN
Total inertia measured in downwards direction
6 TQLIM UP
Maximum load torque allowed upwards (=field weakening power limit)
7 TQLIM DWN
Maximum load torque allowed downwards (=field weakening power limit)
8 POWOP RESET LEV
Speed level where the calculated power optimization reference will be reset to be prepared for a new calculation during the next acceleration.
9 T MAX
Motor maximum relative torque capacity (also called "Pull-out torque" or "Breakdown torque" level) per motor catalogue. Often given as e.g. Tmax/Tn = 2.5 (=250%).
Note: Enter motor Tmax value (as normally given in catalogues for sinusoidal supply = direct-on-line data), without subtracting the 30% "frequency converter supply reduction factor".
If instead having a Tmax/Tn value given as a part of "Inverter parameter settings" values in a motor data sheet, than value must be divided with 0.7 (and multiplied with 100 to get %) before set to parameter 68.9.
10 LOAD TORQ FILT TC
Filter time constant for calculated signal 2.31 LOAD TORQUE % (see also Power
optimization (68) on page 93 ).
11 SLACK ROPE TQ LEV
Detection level for "slack rope", (see page 5-33 for more details on "Slack rope" function). Load torque signal (2.31) dropping below this level is considered a "slack rope", making a Fast stop type 1 to the drive. Setting of -400% (default) will disable the Fast stop.
12 LOADCORR FACT UP
Load correction factor in hoisting direction for LOAD TORQUE % signal 2.31 . To include the mechanical efficiency (in p.u.) of hoist machinery driven by hoist motor as well as motor utilization when hoisting nominal load (i.e. motor torque in p.u. at full load). E.g.: Eff. 0.9 * Util. 1.0 = 0.90.
13 LOADCORR FACT DWN
Load correction factor in lowering direction. Note: efficiency part for lowering is calculated as 1/mech.eff. E.g. 1/0.9=1.10 .
14 RAMP RATE POWOP
Only to be used when a different (usually faster) acceleration time (0 to maximum speed) is required when driving with light load
Set a value for the ramp rate in the power optimization area (above base speed). The value in 68.14 (0 ... 100%) is multplied with parameter 69.2, ACC TIME FORWARD. This results in faster acceleration in hoist up direction, in order to fulfill the requirement of different acceleration times to maximum speed with light and heavy load.
15 RAMP CHANGE SPEED
Set the speed - in percentage of maximum speed - at which the power optimization ramp rate is added, usually at base speed.
If the motor nominal speed is higher than the base speed, it may be better to select the nominal speed.