Rockwell Automation FlexPak 3000 Digital DC Drive Version 4.3 - Manual (Page 62)

5-14 FlexPak 3000 DC Drive Software Reference
5.5 Configuring the Speed Loop Current Limits
Armature current is typically limited through two parameters, POSITIVE CURRENT LIM
(P.005) and NEGATIVE CURRENT LIM (P.006). Configure these parameters so they limit
armature current to a range that is consistent with normal operation of the application.
The current limits can also come from:
• Analog inputs 1 and 2 on the I/O Expansion kit.
• Network input registers 1, 2, or 3 from a network.
When POS CURRENT LIM SEL (P.223) or NEG CURRENT LIM SEL (P.224) is set to REGISTER ,
the register values are automatically clamped to prevent a minimum (non-zero)
current condition.
Normally, the negative current limit is input as a positive value, then converted to a
negative value by an inverter. If needed, the inverter can be disabled by the
NEG CUR
LIM INV EN (P.226) parameter. For example, if the inverter is enabled and the negative
current limit is 150.0% FLA , the actual negative current limit used is –150.0% FLA .
If you change NEG CUR LIM INV EN (P.226), POS CURRENT LIM SEL (P.223) and NEG
CURRENT LIM SEL (P.224) are automatically set to REGISTER . When this occurs, an
alarm is generated to notify you of a possible change in the current limits. Make sure
the settings of
POS CURRENT LIM SEL (P.223), NEG CURRENT LIM SEL (P.224), POSITIVE
CURRENT LIM (P.005), and NEGATIVE CURRENT LIM (P.006) are correct for your
application before operating the drive.
!
ATTENTION: When analog inputs or network registers are used to
control current limits, bipolar values are permitted for the postive and
negative current limits of the current and speed loops. Extreme care
must be exercised when setting the current limit values in this case. If
the negative current limit is set to a non-zero value, the current loop
reference will be clamped to this minimum value, possibly causing
unexpected motor or machine operation, including rapid acceleration or
overspeed. Failure to observe this precaution could result in bodily injury.