M301L 47
10 MIN FRQ (MINIMUM FREQUENCY)
This parameter defines the lower limit of the drive’s speed range. MIN FRQ is used in
conjunction with MAX FRQ (Parameter 11 below) to define the operating range of the drive.
If MIN FRQ is set to a value above 0.0 Hz, the drive will ramp up from 0.0 Hz when given
a start command. Once running, however, the drive will not operate below the MIN FRQ
setting unless the rotation is changed, or a stop command is issued and the drive is
programmed to ramp to a stop.
If the MINIMUM FREQUENCY is set to 0.0 Hz, the drive may be operated in ZERO SPEED
mode (drive is in RUN state, but there is no output to the motor). ZERO SPEED operation
can be used in applications requiring the ability to start and stop the drive using only the
selected speed reference. The drive will start when the speed reference is raised above
0 VDC or 4 mA, and it will stop when the reference is lowered to 0 VDC or 4 mA. Note
that the drive must be initially started using one of the normal start commands (keypad
or terminal strip).
11 MAX FRQ (MAXIMUM FREQUENCY)
This parameter defines the upper limit of the drive’s speed range. MAX FRQ is used in
conjunction with MIN FRQ (Parameter 10 above) to define the operating range of the drive.
WARNING!
Consult motor manufacturer before operating motor above rated
frequency. Overspeeding the motor and/or driven equipment can
cause damage to equipment and injury to personnel!
12 DC BRAKE (DC BRAKE VOLTAGE)
DC braking creates a braking torque by injecting DC voltage into the motor. This parameter
sets the magnitude of that DC voltage. The point at which the drive applies DC braking
to the motor depends on which STOP mode is programmed (either COAST or RAMP,
see Parameter 26 - STOP).
If the drive is set to COAST, DC braking is activated when the stop command is given.
In this case, DC braking helps decelerate the motor. This is useful in applications where
a quick deceleration is desired on a load that would normally take a long time to coast
to a stop.
If the drive is set to RAMP, DC braking is activated when the output frequency reaches
0 Hz. In this case, the drive decelerates the load to a near stop and then DC braking is
used to stop and hold the motor. This is useful in applications where the load needs to
be stopped in a certain position. Similar applications with high-inertia loads utilize both
dynamic braking and DC braking. The dynamic braking allows the high-inertia load to be
decelerated quickly, while the DC braking stops the load in the desired position.
Due to heat generated in the motor, DC braking should only be used in applications
where the load is stopped infrequently. In high duty-cycle applications, dynamic braking is
recommended because the heat is dissipated through external resistor banks, rather than
in the motor. When used, DC BRAKE should be set to the lowest voltage that provides
satisfactory operation in order to minimize motor heating. The maximum voltage available
depends on the voltage rating of the drive.
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