Lenze MCH Series - Manual (Page 54)

50 13435744_EDBMH01_v13
11 MAXIMUM FREQ
This parameter defines the upper limit of the drive’s speed range. MAXIMUM FREQ is
used in conjunction with MINIMUM FREQ (Parameter 10) 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 VOLT
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
method is programmed (either COAST or RAMP, refer to Parameter 26 - STOP
METHOD).
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 VOLT 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.
MAXIMUM DC BRAKE VOLTAGE
MODEL MH200
240 / 200 Vac
MODEL MH400
480 / 400 Vac
MODEL MH500
590 / 480 Vac
24 VOLTS 48 VOLTS 59 VOLTS
13 DC BRAKE TIME
This parameter determines the length of time that the DC braking voltage is applied to
the motor. DC BRAKE TIME should be set to the lowest value that provides satisfactory
operation in order to minimize motor heating.
NOTE:
If this parameter is set to 999.9 seconds (the maximum value), the DC braking
will be continuous. If it is set to .0 seconds, it is disabled.