Specifications
54
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.
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. Refer to the table below:
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!
MAXIMUM DC BRAKE VOLTAGE
MODEL AC4x1 MODEL AC4x2 MODEL AC4x4 MODEL AC4x5
240 / 120 Vac 240 / 200 Vac 480 / 400 Vac 590 / 480 Vac
24 VOLTS 24 VOLTS 48 VOLTS 59 VOLTS