User Manual V 1-4.XX User guide

Troubleshooting 12-19
Using Line Undervolts
You can use Line Undervolts (parameter 27) to set the level of bus
voltage that must be present to complete precharge and a level where
ridethrough can be initiated. If configured as a fault/warning, Line
Undervolts sets the bus voltage level that faults/warns the drive. The
bus voltage level that is used is determined as follows:
Line Undervolts * Inverter Volts (parameter 12) * sqrt(2) = bus
voltage level for ridethroughs, faults, or warnings
Using Test Select 1 and Test Data 1 to View Software
Testpoints
Additional information concerning precharges and ridethroughs is
available through Test Select 1 (parameter 93) and Test Data 1
(parameter 92).
Viewing the Calculated Undervoltage Value of Bus Voltage
To view the value of the calculated undervoltage:
1. Enter a value of 100 into Test Select 1.
2. Monitor Test Data 1.
You can use this to check the actual bus voltage that causes an
undervoltage condition.
Checking the Status of the Precharge
To view the precharge status, enter a value of 12 into Test Select 1,
and then monitor Test Data 1 for the precharge status. The precharge
status is bit encoded as follows:
14
Disables the precharge function after initial power up. Any bus drop or
undervoltage will not result in precharge. This may destroy the drive if
power returns to the system. This should be used where you control the
input impedance or with a front end converter with automatic current
limiting.
15
Disables the ridethrough and precharge functions. If the power lines drop
out, the drive attempts to continue operation as long as any power is
available. This may destroy the drive if power returns to the system. This
should be used only where you control the system’s incoming power and
provide external logic power.
This bit: Has this definition:
file:
Fault Setup
group:
Fault Limits
This bit: When set, indicates that:
0
The precharge function has been completed and the precharge device
should be on. The drive can be enabled only after this bit is set.
1
The drive is in ridethrough. Precharge must be completed and the bus
must return to within 75 volts of the bus voltage tracker before normal
drive operation can resume.
2 A precharge-initiated condition is in ridethrough.
3 A precharge has been requested due to an external fault (input).
4
The converter is ready for precharge and the controller may start its
precharge function. The external precharge board is ok, if present.
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.