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3-2 Operation MN894
Start Adjustments (Refer to Figure 3-1).
Ramp Up Ramp up time (RU) is adjustable from 3 to 50 seconds. RU adjusts the voltage ramp or
the tachometer starting ramp time. For voltage starting, RU adjusts the time it takes the
motor to reach full voltage. Actual acceleration time to full speed depends upon the
motor load and the setting of the additional start adjustments.
For Tach feedback starting, RU adjusts the motor starting time independent of the load
when used with a 0 to 10 VDC tachometer feedback signal. Smooth linear speed ramp
up with constant acceleration is achieved.
Torque Up The initial starting torque (TU) for ramp up is enabled only in the voltage ramp mode.
Usually set high enough to start the motor slowly turning the instant the start button is
pressed.
Pulse Time Starting pulse time (PT) is adjustable from 0 to 1.5 seconds in the voltage ramp mode.
When the start button is pressed, the initial motor voltage depends on the setting of TU.
One second after the start button is pressed, a pulse of approximately 400% FLA will
occur; the duration will depend upon the setting of PT.
Current Limit Current limit (CL) is adjustable from 75 to 400% of FLA. It can be used in both the
voltage and tachometer ramp modes of operation. When CL is enabled (S2-5=ON),
motor starting and stopping current will not exceed the set point of CL, except during PT.
Note: CL must be set high enough to allow the motor to start under maximum load
conditions. In the Tach feedback mode, CL will affect linearity and start and
stop times. The current is held at the CL limit until the motor current
decreases to less than the CL setting, regardless of the RU setting.
Figure 3-1
CL
PT
RU
TU
S
T
A
R
T
Stop Adjustments (Refer to Figure 3-2).
Ramp Down Ramp downtime (RD) extends the stopping time from 5 to 50 seconds. RD can be used
in both the voltage and tachometer modes.
In the tachometer mode, when used with a 0 to 10 VDC tachometer feedback signal, RD
will adjust the actual stopping time independent of motor load condition. Smooth linear
speed ramp down with constant deceleration is achieved.
In the voltage mode, RD adjusts the time it takes to reach minimum motor voltage and
turn off. The actual stopping time will depend on the motor load condition.
Note: Ramp down mode is not suitable for coasting or inertial loads that require
braking. Ramp down will only extend the stopping time.
Torque Down Torque down advance (TD) is adjustable from 0 to 100% advance. TD sets the initial
torque or voltage which ramp down starts and can be used in both voltage and
tachometer modes.
In ramp down mode, when the stop button is pressed, voltage will immediately decrease
to the set point of TD. Control will continue to ramp down to zero speed or voltage,
depending upon RD setting, then the control will turn off.
Figure 3-2
RD
TD
S
T
O
P