Rockwell Automation 1305 AC Drive, Series C, Firmware 6.xx and Up - Manual (Page 103)

Programming 5-35
Feature Select Group (continued)
[Cable Length] Parameter # 143 Factory Default “Short” [Cable Length]
Parameter Type Read & Write
This parameter selects the length of cable that is
connected to the motor.
Important: A setting of “Long” causes the PWM carrier
frequency to be fixed at 2 kHz and Voltage Ring-Up
Reduction software to be enabled.
Important: If “Overload Fault” (F7) occurs – choose “Long”
length.
Units Text Settings “Short”
“Long”
[Rated Slip] Parameter # 146 Factory Default 2.0 Hz [Rated Slip]
Parameter Type Read & Write Minimum 0.0 Hz
This parameter compensates for the inherent slip in an
i d ti
t A f i dd d t th d d
Units 0.1 Hz Maximum 5.0 Hz p p p
induction motor. A frequency is added to the commanded
output frequency based on torque current. The actual value
added may be viewed in [Slip Comp Adder] (parameter
148). If motor shaft speed decreases significantly under
heavy loads then this value should be increased. A setting
of 0.0 Hz disables the function.
This parameter can be set more accurately based on motor
nameplate RPM at full load. Use the formula and table
shown.
Motor Sync Speed – Nameplate RPM
Motor Sync Speed
Motor
Nameplate
Hertz
Drive Rated Amps
Motor FLA
x x Rated Slip =
Example
Drive 1 HP, 460V
2.3 Amps Rated
Motor Motor Sync Speed = 1800 RPM
Nameplate RPM = 1725 RPM
Nameplate Hertz = 60 Hz
Motor FLA = 1.7 Amps
[( )]
1800 – 1725
1800
60
2.3
1.7
x x Rated Slip =
[( )] ) ( ) (
= 3.38 Hz
Note: Instability may occur if [Rated Slip] is set too high with operating frequencies below 10 Hz.
Motor Sync Speed
Poles
60 Hz 50 Hz
2 3600 3000
4 1800 1500
6 1200 1000
8 900 750
12 600 500
( ) ) (
Set [Rated Slip] to 3.4 Hz.