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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 protec-
tion 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 to –22V.
NOTE: The use of remote programming (via RS 232 or GPIB) automatically asserts Indepen-
dent 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 (PROTECT may be seen only when external limits are
in use) message is displayed at the upper right of the LCD, and the power supply continues
operation.
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.
BOP HIPWR 080709
FIGURE 3-7.
MAX/MIN SETTINGS MENU
3-15
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