Control / Limits
7100A User Manual
4-4
4.2.2. CURRENT AND POWER LIMITATION
With the contol option VICL, the following are available:
• ‘
I lim
’ current calibration potentiometer
• ‘
VI lim
’ power calibration potentiometer
•
HRC
calibration control signal on the ‘
ADJ.CAL
’ terminal block
Recalibration is possible:
• current
I
max
from
20%
to
100%
of
I
N
• power
P
max
from
50%
to
100%
of (
V
N
. I
max
).
The
HRC
setting control signal (‘
ADJ.CAL
’ terminal block) can be used to aid setting with the ‘
I lim
’
and ‘
VI lim
’ potentiometers whether or not the thyristor unit is firing.
Setting current and power limitation
The value of the DC voltage between terminals
HRC
(67) and
0VC
(66) represents:
• The
image
of the maximum
current
(‘
VI lim
’ potentiometer fully turned in the direction of the
arrow)
• The
image
of the maximum recalibrated
power
(
1 V
corresponds to
100% P
N
).
The control signal is equal to
1 V
if calibrations are
nominal
(I
max
= I
N
and P
max
= P
N
).
The minimum value of the signal is
0.1 V
(I
max
= 20% and ‘VI lim’ set to 50% of V
N
. I
max
).
Setting:
1. Turn the ‘
VI lim
’ potentiometer fully round in the
direction of the arrow (nominal power).
2. Use the ‘
I lim
’ potentiometer to set the
I
max
value.
3. Use the ‘
VI lim
’ potentiometer to set the
P
max
value.
Check the resulting power setting on the
HRC
signal
(accounting for
I
max
) .
Important:
The current limitation must be done before adjusting the power limitation.
ADJ.CAL 66 0VC 67 HRC
ANA.IN 31 0V
A
32 RI 33 5V
A
V
71A4_Régulation_ENG_Iss2_1.qxp 1/09/06 16:15 Page 4-4
