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Altivar
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58 TRX AC Drives
Assignment of Logic Inputs (LIx)
55
09/2003
© 2000–2003 Schneider Electric All Rights Reserved
Controlled Stop Functions
The Controlled Stop functions provide alternate stopping methods to the normal drive controller stop.
Normally, the drive controller follows the deceleration ramp on a command to stop. To use the Controlled
Stop function, one logic input (LI) must be assigned. The input is active at state 0 (open) for a Freewheel
Stop or Fast Stop, and is active at state 1 (closed) for DC Injection Braking. These stop requests always
have priority over a normal stop or a Run signal. Three controlled stop methods are available:
• Freewheel Stop/Run Permissive
The drive controller output is turned off and the motor coasts to a stop according to the inertia and
resistive torque of the load. This method is often used in applications where Run Permissive is used
as an electrical safety device.
•Fast Stop
Braking with deceleration ramp time divided by a coefficient adjustable from 1 to 10. This method is
often used for materials handling applications and provides the quickest way to stop without
additional hardware.
• DC Injection Braking
Adjustment of time (0 to 30 s, preset at 0.5 s) and current (10% to 136% of nominal controller current
in a high-torque application, preset at 70%). It is possible to set continuous braking current from 10%
to 100% of nominal motor current (factory setting is 50%). After 30 s, the current automatically goes
to 50%. This method is often used for applications involving fans since it eliminates the need for the
addition of a braking resistor.
Note that after a stop (frequency less than 0.1 Hz), DC Injection Braking may be combined with the
other methods. For this situation, only the current injected after 30 s can be adjusted.
Switching Between Two Motors
This function allows a single drive controller to control two motors with different power ratings, one at a
time. Activating this parameter automatically scales the DC injection current, brake release current, and
nominal motor current based on a programmable scaling factor and the larger motor parameters that
have been configured. This function inhibits motor thermal protection of the second motor. External
contactor control for both motors and external motor thermal protection for the second motor is required
for using this function.
Freewheel Stop Below Selectable Frequency
This parameter allows the drive controller to freewheel stop below a programmable frequency. After a
stop command is received and the drive has followed the deceleration ramp to the programmed
frequency, the drive controller output is turned off and the motor coasts to a stop according to the inertia
and resistive torque of the load.
Torque Limit by Logic Input (Constant Torque Rated Products)
This function allows a logic input to be assigned a second level of torque limit. The associated torque
level is factory set at 200% and is adjustable from 0-200% of the drive controller constant torque rating.
When the assigned logic input is closed (set to state 1) the maximum torque is limited to the configured
value. This feature can be used in the following type of applications:
• At the end of a material handling cycle when it may be useful to stall the motor as the load meets a
barrier.
• Cut-to-length applications with the material stopped while maintaining some motor torque to hold the
material.
f
(
Hz
)
123 4
CntrlStop.eps
1 = Fast Stop
2 = DC Injection Braking
3 = Normal stop on dec. ramp
4 = Freewheel Stop
Controlled Stop
Diagram