Rockwell Automation 1336T FORCE Series B - Manual (Page 221)

Chapter 6
Troubleshooting
6–9
To understand the precharge and ridethrough faults, you need a basic
understanding of how these functions work, as well as the options that
you can use to alter the way precharge and ridethrough operate in the
1336 FORCE drive.
Understanding Precharge
The precharge of the drive has different circuits depending on drive size.
For the precharge operation for large horsepower (40 hp and larger)
standalone drives, the precharge starts the SCR phase advance and
completes precharge when the bus is stable. For all other drive types,
precharge is completed after a stable bus voltage is achieved and the
precharge device (SCR or relay) by–passes the precharge resistor. For
common bus operation, set bit 12 in Precharge / Ridethrough Selection
(parameter 223). The drive current and voltage ratings stored in EEProm
determine the standalone operation.
With the default configuration, the following conditions are needed to
complete precharge:
•
a stable bus voltage for a minimum of 300 milliseconds
•
a bus voltage greater than the value set in Undervoltage Setpoint
(parameter 224)
•
a valid control status from the precharge board, if present
You can modify the default configuration for common bus drives by
using the external fault (input) and the precharge exit option:
•
You can use the external fault input with a cabinet disconnect switch
to force precharge when the disconnect is opened and the drive is dis-
abled. This may reduce current stress when the disconnect is closed
again.
•
You can use the exit precharge option to let the precharge complete
after the precharge timeout period (30 seconds) when the bus voltage
is not stable. All other conditions must be met. This is often used in
the case of common or shared bus configurations where other drive(s)
may be causing bus voltage variations. Only use this option where
needed otherwise excessive inrush current could open or weaken the
line fuses.
NOTE: The precharge timeout fault (Parameter 86) must be disabled
to use this option.
Before you can enable the inverter, all drive types must complete a first
time precharge. This is required even if you have set the disable
precharge function by setting bit 14 of Precharge/Ridethrough Selection
(parameter 223).
Understanding Precharge
and Ridethrough Faults