User Manual V 1-4.XX User guide

12-20 Troubleshooting
Enabling Fast Flux Up
You can use fast flux up to achieve rated flux conditions and
consequently high torque as fast as possible after an enable. Under
default conditions (no fast flux up), the drive brings the motor to rated
flux conditions in a time proportional to the rotor time constant of the
motor. These times range from 50 milliseconds for small motors to
several seconds for large motors. If a high load is attempting to be
started, no acceleration occurs until that time has elapsed. Enabling
fast flux up can decrease that time by a factor of 5 to 10.
You can enable the fast flux up function of the drive by setting bit 8 of
Bus/Brake Opts (parameter 13). In this case:
1. An amount of motor current set by Fast Flux Level
(parameter 78) is applied to the flux producing axis for a time
estimated to produce rated flux in the motor. The value of Fast
Flux Level is set to 200% by default. You can reduce this value if
it causes an undesirable torque pulsation. The time required to
reach rated flux increases when you reduce this value.
2. The flux current is reset to nominal.
3. The drive is allowed to start producing torque.
4. Use Test Select 1 (parameter 93) to check the approximate fluxing
time. Enter a value of 86 into Test Select 1 to display the fluxing
time in Test Data 1 (parameter 92). The time delay is given in
seconds x 0.000977. If the flux time is 0, no fast flux up occurs
and the drive starts normally. If at least 50% of the commanded
current is not measured, you can configure the drive to fault at
this time using Fault Select 1 (Open Circuit).
Forcing the Drive to Complete a Precharge
In some cases, the precharge may not complete due to external bus
disturbances. Setting bit 11 in Bus/Brake Opts forces the precharge to
complete at the precharge interval (default 30 seconds). This may
cause precharge damage and should only be used when large inrush
currents cannot occur.
7
The precharge function cannot complete because the measured bus
voltage is less than 75 volts below the bus voltage tracker. This only
applies to precharging after a ridethrough.
8 The precharge device has been commanded ON.
9 Not used.
10 An exit from precharge was requested.
11 Precharge was skipped due to an enable dropout.
12 An initial (first) precharge is executed.
13 A high horsepower drive type is being used.
This bit: When set, indicates that:
file:
Application
group:
Fast Flux Up