Specifications

Altivar
®
31 Adjustable Speed AC Drives
Functions
© 2004–2005 Schneider Electric All Rights Reserved
36
4/2005
Automatic adaptation of the deceleration ramp
If the initial deceleration ramp setting is too low for the load inertia, this
function automatically modifies the ramp, preventing the drive from faulting
due to excessive braking.
This function is suited to all applications not requiring precise stopping and
not using braking resistors.
Automatic adaptation must be cancelled if the machine has position control
with stopping on a ramp and a braking resistor installed. This function is
automatically disabled if the brake sequence is configured.
Voltage/frequency ratio
Motor and power supply characteristics
These characteristics determine the limit values for the voltage/frequency
ratio according to the line supply, the motor, and the application.
The following values should be set for variable or constant torque
applications, with or without overspeed:
• the base frequency, which corresponds to the supply
• the nominal motor frequency (in Hz) given on the motor nameplate
• the nominal motor voltage (in V) given on the motor nameplate
• the maximum output frequency of the drive (in Hz)
Type of voltage/frequency ratio
This designation adapts the voltage/frequency ratio to the application, to
optimize performance for the following:
• Ratio L—Constant torque applications (machines with average loads
operating at low speed) with motors connected in parallel or with special
motors (e.g., resistive cage motor)
• Ratio P—Variable torque applications (pumps, fans)
• Ratio n—Machines with heavy loads operating at low speed, with fast
cycles, or with sensorless flux vector control
• Ratio nLd—Energy saving, for machines with slow speed and torque
variations. Voltage is automatically reduced to a minimum according to the
necessary torque.
Auto-tuning
Auto-tuning optimizes application performance. It can be executed:
• when the operator sends a command via the local or remote keypad
display or the serial link
• each time the drive is powered up
• each time a run command is sent
• when the logic input assigned to this function transitions from 0 to 1
Adjusting the voltage/frequency ratio in PowerSuite software
563715
L
n
P
U (V)
Un
frn
f (Hz)
Un: Nominal motor voltage
frn: Nominal motor frequency
563530
Courtesy of Steven Engineering, Inc.-230 Ryan Way, South San Francisco, CA 94080-6370-Main Office: [phone]-Outside Local Area: [phone]-www.stevenengineering.com