Chapter 6
Troubleshooting
6–14
5
The measured bus voltage is not stable (there is a variation of
greater than ±25 volts) and the precharge cannot finish.
6 The DC bus voltage is less than line undervolts.
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.
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
Precharge / Ridethrough Selection (parameter 223). In this case:
Use Testpoint Select #1 (parameter 273) to check the approximate
fluxing time. Enter a value of 86 into Testpoint Select #1 to display the
fluxing time in Testpoint Data #1 (parameter 274). 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
CP Fault Warning Configuration Select (P86).
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