455-461 Series
Reading in diagnostic
position 5
I 2
Iams
10 V
100%
100%
5 V
50%
71%
Threshold current limit. External potentiometer
This limit independent of the drive signal is:
• 110% of the nominal unit current (terminal 14 directly connected to terminal 12),
• or adjustable controlled by an external potentiometer, of approximately 10 kf2, connected
between terminal 12 (+ 10 V) and terminal 6 (0 V); the cursor is connected to terminal 14,
• or adjustable controlled by an external DC voltage (0-10 V); R Z 150
The limit of 12 is linear from 0 to 10 V. At 10 V read on position 5 of the diagnostic unit), the
limit acts at approximately 110 % of the nominal current.
For the threshold current limit setting:
• After installing the unit and setting the linear limit (with potentiometer on front
fascia), switch on the unit.
• Set the drive to the maximum value and gradually decrease the "Threshold
current limit" setpoint until the current starts to decrease.
• Identify the setpoint of the corresponding current limit in diagnostic position 5,
and increase it by approximately 10% so that it only acts as a safety device in
relation to the linear current limit.
The threshold current limit can be
preset
when a unit of the series is powered but not
energized.
The value of the square of the rms load current is proportional to the "Threshold current limit"
setpoint observed at diagnostic point 5. Two examples are given in the table below.
Table 4.7
The
simultaneous
use of two limits is possible. For example, it makes it possible to set an
absolute current limit with the threshold limit (external potentiometer or external voltage) and
adjust the linear setpoint limit with the front fascia.
4-26
451-461
User
Manual
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