KEPCO BOP-ME 1KW, Operator'S Manual

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3-18
BOP HIPWR 091719
Selection of Bipolar does not immediately change the protect limit values; it changes how the
protect settings are displayed and set from the power-up screen. So if
maximum/minimum pro-
tection limits were set to different values, (e.g, for BOP 36-28MG, current mode, no load, +V
Protect Max = 25V and –V Protect Min = 7V) when Bipolar is selected, the previous protection
values (+25, –7) will remain in place until a new value is entered in the Voltage Protection field.
When a new Voltage Protect setting, e.g., 22V, is entered with Bipolar mode selected, +Voltage
Protect is set to +22V and -Voltage Protect is set to –22V.
NOTE: The use of remote programming (via LAN or GPIB) automatically asserts Independent
protection limits. Once the unit is returned to local mode, the unit is automatically
returned to Bipolar mode.
3.3.3.2 UNDERSTANDING VOLTAGE AND CURRENT PROTECT LIMITS
These values are the references for the complementary channels: voltage in current mode and
current in voltage mode. The range for these values is between a minimum (box) value (see Fig-
ure 1-3) and 1% above the rated nominal value (see PAR. 3.3.4.2). If the unit is in voltage mode,
it will enter current protect mode when the load demands more current and energy than permit-
ted by the ±current protect settings. Similarly, if the unit is in current mode, it will enter voltage
protect mode if the load demands more voltage and energy than permitted by the ±voltage pro-
tect settings. When the protect settings are exceeded, the protection channel limits the output, a
VPROTECT, CPROTECT or PROTECT message is displayed at the upper right of the LCD,
and the power supply continues operation (PROTECT may be seen only when external limits
are in use). When VPROTECT is displayed, bit 12 of the questionable status register is set.
When CPROTECT is displayed, bit 13 of the of the questionable status register is set. When
PROTECT is displayed, both bits 12 and 13 of the questionable status register are set. (see
para 3.6.7.3).
3.3.3.3 HIDDEN VOLTAGE AND CURRENT PROTECT LIMITS
The BOP employs two back-up channels which function as safety backups if a main channel
fails. The backup channel limits are fixed and not user accessible. These limits are set to 5%
over the nominal (rated) values for voltage or current. If the software limits for a main channel is
changed (PAR. 3.3.4.1), the corresponding protect channel limit is automatically changed to be
5% of the nominal (rated) value above the user-programmed software limit.
3.3.4 CHANGING MAXIMUM OR MINIMUM SOFTWARE-CONTROLLED LIMITS
The maximum or minimum allowable voltage and current settings of the unit can be reduced
from the nominal using the Max/Min Settings menu (Table 3-5). which lists the system’s soft-
ware-controlled voltage and current limits (+Voltage Max, –Voltage Min, +Current Max, –Current
Min) as well as the corresponding protection limits organized by operating mode. The default
values of the system limits are established by the Model: the nominal (rated) values for voltage
and current and 1.01 x the nominal (rated) values for protection. The default values can be
reduced by modifying the highlighted parameter. The unit will not accept local or remote com-
mands that exceed the system limits. The system limits are always in effect, even when the unit
is controlled by an external reference.
If system limits are changed, the protection limits
must be changed to correspond to the new system limits. As an example, chVolt-
age Max and –Voltage Min of a BOP 36-28MG to ±3V, respectively, causes the unit to behave
as if it was a BOP 3-28MG. In this case it is important to change the +V Protect Max and –V Pro-
tect Min limits (e.g., to ±3.3V, respectively) so that the load is protected when operating in Cur-
rent Mode. System limits are absolute values (do not use minus sign for negative limits).