Specifications

Altivar
®
31 Adjustable Speed AC Drives
Functions
© 2004–2005 Schneider Electric All Rights Reserved
44
4/2005
Fast stop
This function allows a braked stop with a deceleration ramp time (divided by
2 to 10) acceptable for the drive to avoid an excessive braking fault.
Fast stop is used for conveyors with emergency stop electrical braking.
It is achieved by enabling a logic input or by configuring a normal stop as a
fast stop (on the removal of a run command or the initiation of a stop
command).
DC injection stop
This function is for low-speed braking of high inertia fans or for maintaining
torque when stopping fans located in an airflow.
A DC injection stop is achieved by enabling a logic input or by configuring a
normal stop as a DC injection stop (on the removal of a run command or the
initiation of a stop command).
The DC value and the injection braking time are adjustable.
Brake control
With this function active, the drive manages the brake control sequence to
synchronize the control of an electromagnetic brake with the starting and
stopping of the motor, to avoid jolts and load veering.
• Adjustable values for releasing the brake:
current threshold and time delay
• Adjustable values for engaging the brake:
frequency threshold and time delay
This function is enabled by assigning brake control to relay logic output R2 or
logic output AOC.
Brake control is suited to material handling applications with movements
equipped with electromagnetic brakes (hoisting) and machines requiring a
parking brake (unbalanced machines).
Principle
• Vertical lifting movement
Maintain the motor torque in an upward direction when the brake is
released and engaged, to hold the load and start smoothly as soon as the
brake is released.
• Horizontal lifting movement
Synchronize the brake release with the build-up of torque on starting, and
the brake engagement with zero speed on stopping, to prevent jerking.
t
t
t
t
0
0
1
Ibr
t1
0
bEn
0
1
t
0
t2
brL
1
0
Motor speed
Accessible settings:
t1: Brake release time delay (brt)
t2: Brake engage time delay (bEt)
Brake control
Relay or logic output
Motor current
Brake release
current
Motor frequency
lbr: Brake release current
brL: Brake release frequency
bEN: Brake engage frequency
LI forward
or reverse
Brake status
Engaged
Released
8800CT0401 brake control.eps
Speed
reference
Speed
reference
Courtesy of Steven Engineering, Inc.-230 Ryan Way, South San Francisco, CA 94080-6370-Main Office: [phone]-Outside Local Area: [phone]-www.stevenengineering.com