Avtron ADDvantage-32, Manual

Page: 96 / 290

Control Block Description
ADDvantage-32
4-34
Tapered Current Limits
If tapered current limits are desired, the BY I2R input must be low by configuring
P***:BYPASS I2R = ZERO BIT. The current limit block constantly monitors the I2R
Trip input (A***:IIR INTEGR) to detect when the motor armature current rises above
110%. A hidden I2R Trip table is created within the current limit block to limit the POS
LIM and NEG LIM outputs when the motor armature current rises above 110%. The
POS LIM and NEG LIM outputs will equal the smaller value of either the table output or
the POS I and NEG I inputs. The table output will equal the START PER (C***:START
PER S) when IIR INTEGR < 25 counts. When IIR INTEGR = 100 counts, the table
output will equal END PER (C***:END PER S) where the user should enter a value of
100% or less. When IIR INTEGR is between 25 to 100 counts, the table output is equal
to the interpolation between START PER and END PER.
The POS LIM and NEG LIM outputs are then checked against another hidden SFDBK
table within the block to check the current limits by the SFDBK input (A***:ABS ACT
SPD).
When SFDBK < BRK SPD, the speed table output will equal START PER S. IF SFDBK
> MAX SPD, the speed table output will equal END PER S where the user should enter a
value of 100% or less. When SFDBK is between BRK SPD and MAX SPD, the speed
table output will equal the interpolation between START PER S and END PER S. The
POS LIM and NEG LIM outputs will equal the smaller value of either the table output or
the POS I and NEG I inputs.
Block Positive Bridge
The Positive Bridge can be blocked by making the BLOCK POS input high by
configuring P***:BLOCK POS B = ONE BIT. The POS LIM output will equal zero
when BLOCK POS is set high.
If BLOCK POS is set low (zero bit), POS LIM output will equal the smallest value
between POS I input, the output of the I2R Trip table or the SFDBK table.
Block Negative Bridge
The Negative Bridge can be blocked by making the BLOCK NEG input high by
configuring P***:BLOCK NEG B = ONE BIT. The NEG LIM output will equal zero
when BLOCK NEG is set high.
If BLOCK NEG is set low (zero bit), NEG LIM output will equal the negative of the
smallest value between NEG I input, the output of the I2R Trip table or the SFDBK table.