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3.4.4
EXTERNAL PROTECTION LIMITS
When PROTECTION LIMIT on the Reference Menu is set to EXTERNAL, the protect limits are
determined by four analog signals referenced to Ground (pin 12) which are applied to the Ana-
log I/O Port (see PAR. 3.4.4).
To be functional this feature must first be configured from the front panel. From the power-up
screen press
$
press
to save. Then press
Only two signals are active, affecting the complementary protect channel, ±current protect limit
for voltage mode and ±voltage protect limit for current mode. A voltage between +1V and +10V
at the following pins (referenced to Ground, pin 12) will control the corresponding protection
parameter between 10% of the nominal value (see Figure 1-3) and the corresponding positive
or negative nominal full scale value.
•
–I_LIM_EXT (pin 5) - This +1V to +10V analog signal sets the negative current protect
limit from 10% of the nominal value to –full scale current. +10V corresponds to rated
minimum (maximum negative) current (e.g., for BOP 36-28MG, +10V sets negative cur-
rent limit to –28A).
•
–V_LIM_EXT (pin 6) - This +1V to +10V analog signal sets the negative voltage protect
limit from 10% of the nominal value to –full scale voltage. +10V corresponds to rated
minimum (maximum negative) voltage (e.g., for BOP 36-28MG, +10V sets negative volt-
age limit to –36V).
•
+I_LIM_EXT (pin 13) - This +1V to +10V analog signal sets the positive current protect
limit from 10% of the nominal value to full scale current. +10V corresponds to rated max-
imum current (e.g., for BOP 36-28MG, +10V sets positive current limit to +28A).
•
+V_LIM_EXT (pin 14) - This +1V to +10V analog signal sets the positive voltage protect
limit from 10% of the nominal value to full scale voltage. +10V corresponds to rated max-
imum voltage (e.g., for BOP 36-28MG, +10V sets positive voltage limit to +36V).
The maximum frequency of an a-c signal used for the external protection limit must be at least
100 times lower that the sampling rate of the external signal (100Hz), resulting in a bandwidth of
1Hz.
The external programming circuit must be able to sink 0.15mA maximum provided by the BOP.
When the input is an open circuit, the corresponding input signal automatically goes to 20%
above the nominal protection limit.
NOTE: Each time Protection Limit setting is changed, the unit generates an internal *RST
reset command (see PAR. A.11) requiring the BOP output to be reprogrammed.
3.4.4.1
USING BOTH LOCAL/DIGITAL AND EXTERNAL PROTECTION LIMITS
When PROTECTION LIMIT on the Reference Menu is set to Lesser Limit, the protect limits are
automatically selected from either 1) the external analog voltage applied to the Analog I/O port
(see PAR. 3.4.4) or 2) the value set from the keypad or SCPI command. Whichever limit has a
lower absolute value (closest to zero) has effect.
To be functional this feature must first be configured from the front panel. From the power-up
screen press
$
and press
exit. NOTE: Each time Protection Limit setting is changed, the unit generates an internal *RST
reset command (see PAR. A.11) requiring the BOP output to be reprogrammed.
3-40
$
, and highlight Protection Limit. Press
%
to apply the changes (without saving for power-up) and exit.
$
, and highlight Protection Limit. Press
%
to save. Then press
!
to modify, then highlight External and
!
to modify, then highlight Lesser Limit
to apply the changes (without saving for power-up) and
BOP HIPWR 080709
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