Chapter 6 – Parameters
ACH 500 Programming Manual
6-19
Figure 6-4 shows DC Hold.
Figure 6-4 DC Hold
When both reference and output frequencies drop below 1.5 Hz, the drive will
stop generating sinusoidal current and inject DC into the motor. The voltage
value is the voltage set in the DC Hold Voltage. When the reference frequency
goes above 1.5 Hz, the DC will be removed and normal drive function
resumes.
DC Hold has no effect if the Start signal is deactivated.
Note: Injecting DC voltage into the motor causes the motor to heat up. In
applications where long DC Hold times are required, externally
ventilated motors should be used. In a long DC Hold period, the DC
Hold cannot keep the motor shaft from rotating if a constant load is
applied to the motor.
6 DC HOLD VOLTAGE
Sets the voltage level applied to the motor when DC Hold is activated. Range
is from 0.01 to 0.1 times the nominal voltage.
7 DC-BRAKE VOLTAGE
When the stop function is set to
DC BRAKE
, this parameter sets the voltage
injected into the motor. The factory setting is suitable for a nominal size
motor. If braking is too sudden, decrease this value. If braking is not
sufficient, increase this value.
8 DC-BRAKE TIME
When the stop function is set to
DC BRAKE
, this parameter sets the DC
injection time in seconds. If the braking time is too short, the drive stops by
coasting after the DC-Brake Time has elapsed.
1.5 Hz
t
t
f
motor
Ref.
DC Hold
