83
-
5
15
-
0
00
Rev.
B
37
5.4
UNDER VOLTAGE LIMIT (UVL)
The UVL prevents adjustment of the Output Vol
t
age below a certain limit. The combination of UVL
and OVP functions, allow the user to create a protec
tion window for sensitive load circuitry.
5.4.1
Setting the UVL level
Setting the UVL can be made when the power supply output is Enabled(O n) or Disabled(Of f). To set
the UVL level, press the OVP/UVL button TWICE, so that the CURRENT meter shows “UUL”. The
VOL
TAGE meter shows the UVL setting level. Rotate the VOLTAGE encoder knob to adjust the UVL
level. The display willshow ‘UUL” and the setting value for 5 seconds after t he adjustment has been
completed and then will return to its previous state.
UVL setting
values are limited at the maximum level to approximately95% of the Output Voltage se
t-
ting. Attempting to adjust the UVL above this limit will result in no response to the adjustment attempt.
The minimum UVL se
t
ting is zero.
5.5
FOLDBACK PROTECTION
Foldback
protection will shut down the power supplyoutput if the load current exceeds the current
limit setting level. This protection is useful when the load circuitry is sensitive to an overcurrent cond
i-
tion.
5.5.1
Setting the Foldback protection
To arm the Foldback p
rotection, the FOLD button should be pressed so that the FOLD LED illum
i-
nates. In this condition, transition from Constant Voltage to Constant Current mode will activate the
Foldback protection. Activation of the Foldback protection disables the power supp
ly output, causes
the ALARM LED to blink and displays“ Fb” on the VOLTAGE meter.
5.5.2
Resetting activated Foldback protection
There are four methods to reset an activated Foldback protection.
1.
Press the OUT button. The power supply output is enabled and the Out
put Voltage and Cu
r
rent
will return to their last setting. In this method, the Foldback protection remains armed, therefore if
the load current is higher than the current limit setting, the Foldback protection will be activated
again.
2.
Press the FOLD button
to cancel the Foldback protection. The power supply output will be di
s-
abled and the VOLTAGE display will show“OFF”. Press t he OUT button to enable the powersu
p-
ply output.
3.
Turn the power supply output Off and then On using the SO control (refer to Sectio
n 5.7). In this
method the Foldback protection remains armed, therefore if the load current is higher than the
output current setting, the Foldback prote
c
tion will be activated.
4.
Turn the power supply Off using the AC On/Off switch, wait until the front pan
el display turns Off,
then turn the unit back ON again. The power supply output is enabled and the Output Voltage and
Current will return to their last setting. In this method, the Foldback protection remains armed,
therefore if the load current is higher
than the output current setting, the Foldback protection will
be activated again.
5.6
OUTPUT ON/OFF CONTROL
The Output On/Off Enables or Disables the power supply output. Use this function to make adjus
t-
ments to either the power supply or the load without shu
tting off the AC power. The Output On/Off
can be activated from the front panel using the OUT button or from the rear panel J1 connector. The
OUT button can be pressed at any time to Enable or Disable the power supply output. When the ou
t-
put is disabled, t
he Output Voltage and Current fall to zero and the VOLTAGE display shows “OFF”.
5.7
OUTPUT SHUT
-
OFF (SO) CONTROL VIA REAR PANELJ1 CONNECTOR
Contacts 2, 3 and 15 of J1 (Fig.4
-
2, Item 5) serve as Output Shut
-
Off (SO) terminals. The SO term
i-
nals accept a 2.5V t
o 15V signal or Open
-
Short contact to disable or enable the power supply output.
The SO function will be activated only whena t ransitionf rom On to Off is detected after applying AC
power to the unit. (Thus, in Auto
-
Restart mode, the output will be Enable
d after applying AC power;
even if SO is at an Off level). After an On to Off trans
i
tion it is detected, the SO will Enable or Disable
the power supply output according to the signal level or the short/open applied to J1. This function is