WEG CFW700, Programming And Troubleshooting Manual

Page: 121 / 223

Functions Common to all the Control Modes
12
CFW700 | 12-13
P0332 – Dead Time
Adjustable
Range:
0.1 to 10.0 s
Factory
Setting:
1.0 s
Properties: V/f and VVW
Access groups
via HMI:
Description:
The parameter P0332 sets the minimum time that the inverter will wait to activate the motor again, which is
necessary for the motor demagnetization.
In the Ride-Through function case, the time is counted starting from the line drop. However in the Flying Start
function actuation, the counting begins after the “Run/Stop=Run” command is given.
For the correct operation, this time must be adjusted to twice the motor rotor constant (see table available at
P0412 in
item 11.8.5 - Self-Tuning ).
12.5.4 Vector Ride-Through
Different from the V/f and VVW modes, in the vector mode the Ride-Through function tries to regulate the DC link
voltage during the line failure. The energy necessary to keep the aggregate working is obtained from the motor
kinetic energy (inertia) by means of its deceleration. Thus, at the line return the motor is reaccelerated to the speed
defined by the reference.
After the line failure (t0), the DC link voltage (U
d
) starts diminishing according to a rate depending on the motor load
condition, being able to reach the undervoltage level (t2) if the Ride-Through function is not working. The typical
necessary time for this to occur, with rated load, is from a magnitude of 5 to 15 ms.
With the Ride-Through function active, the line loss is detected when the U
d
voltage reaches a value below the
“DC Link Power Loss” value (t1), defined at the parameter P0321. The inverter initiates a controlled deceleration of
the motor immediately, regenerating energy to the DC link in order to keep the motor operating with the U
d
voltage
regulated at the value “DC Link Ride-Through” (P0322).
In case that the line does not return, the aggregate remains in this condition the longest possible time (depends on
the energetic balance) until undervoltage (F021 in t5) occurs. If the line returns before the undervoltage occurrence
(t3), the inverter will detect its return when the U
d
voltage reaches the “DC Link Power Back” (t4) level, defined at
the parameter P0323. The motor is then reaccelerated, following the adjusted ramp, from the actual speed value
to the value defined by the speed reference (P0001) (refer to the
figure 12.6 ).