KEPCO BIT 4886 Operator Manual - Manual (Page 35)

BIT 4886 120413
4-1
SECTION 4 - OPERATION
4.1 GENERAL
The Kepco BOP Power Supply, with an installed BIT 4886 Interface Card, may be programmed
over the IEEE 488 standard communication bus (General Purpose Interface Bus, GPIB) using
SCPI (Standard Commands for Programmable Instruments). SCPI provides a common lan-
guage used in an automatic test system. (Refer to Table 2-3 for input/output signal allocations.)
CAUTION: DO NOT repeatedly toggle the circuit breaker/switch as this may cause unit to fault.
Set Power ON/OFF circuit breaker/switch on front panel to ON. If actuator does not
lock when released, wait a few seconds before trying again. The circuit breaker is
“trip-free” design; if overload exists, contacts cannot be held closed by actuator.
NOTE: Upon power up, the BOP output is set to off, VOLTage and CURRent are set to 0.
VOLTage and CURRent commands will not change the BOP output until the command
OUTPut ON is sent to the BIT 4886.
4.1.1 PROGRAMMING TECHNIQUES TO OPTIMIZE POWER SUPPLY PERFORMANCE
Proper programming techniques can offer significant response time improvement and reduce
undesirable transients at the power supply output. The key to performance optimization is to
minimize mode changes (voltage mode/current limit to current mode/voltage limit or vice versa).
Mode changes should be limited to changes in load conditions (to which the power supply will
respond automatically), or by programming the limit parameter when required by the user appli-
cation.
The proper way to program the power supply is to initially program the operating parameter to
zero and the complementary limit parameter to the desired maximum value. Subsequent com-
mands should change only the operating parameter. (The operating parameter is the parameter
that controls the output, e.g., voltage controls the output in voltage mode, current in current
mode.) The complementary limit parameter should be programmed only when there is a need to
change it.
4.1.1.1 SETTING BOP VOLTAGE AND CURRENT LIMITS
There are no voltage or current protection settings that can be accessed through the GPIB inter-
face. The limit controls on the BOP front panel (with the screw driver adjustment) can be used to
limit output voltage or current. The limit control settings from the BOP front panel are fixed and
are not computer-controllable. A common use of these controls is to set -V limit to 0 to prevent
the BOP from supplying a negative output voltage.
The BIT 4886 controls the BOP via two channels: the main channel, which is defined by the
operating mode, and the limit channel. In voltage mode, the main channel handles output volt-
age and the limit channel handles current limit. In current mode the main channel handles out-
put current and the limit channel handles voltage limit.
• If the BOP is operating in voltage mode, sending VOLT sxxxx controls the main channel,
and thus the output voltage (where s = sign, + or – and xxxx = the absolute value of out-
put voltage). Sending CURR sxxxx controls current limit (where s = sign, + or – and xxxx
= the absolute value of current limit.
• If the BOP is operating in current mode, sending CURR sxxxx controls the main channel,