83
-
507
-
013 Rev. D
36
5.4
UNDER VOLTAGE LIMIT (UVL)
The UVL prevents adjustment of the Output Vol
t
age below a certain lim
it. The combination of UVL
and OVP functions, allow the user to create a protection 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 (On) or Disabled (Off). To set
the UVL level,
press the OVP/UVL button TWICE, so that the CURRENT meter shows “UUL”. The
VOLTAGE meter shows the UVL setting level. Rotate the VOLTAGE encoder knob to adjust the UVL
level. The display will show ‘UUL” and the setting value for 5 seconds after the adjust
ment has been
completed and then will return to its previous state.
UVL setting values are limited at the maximum level to approximately 95% of the Output Voltage se
t-
ting. Attempting to adjust the UVL above this limit will result in no response to the adju
stment attempt.
The minimum UVL se
t
ting is zero.
5.5
FOLDBACK PROTECTION
Foldback protection will shut down the power supply output 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 protection, 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
Fol
dback protection. Activation of the Foldback protection disables the power supply 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 pr
otection.
1.
Press the OUT button. The power supply output is enabled and the Output 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 the OUT button to enable the power su
p-
ply output.
3.
Tur
n the power supply output Off and then On using the SO control (refer to Section 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 panel 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 shutting 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 ti
me to Enable or Disable the power supply output. When the ou
t-
put is disabled, the Output Voltage and Current fall to zero and the VOLTAGE display shows “OFF”.
5.7
OUTPUT SHUT
-
OFF (SO) CONTROL VIA REAR PANEL J1 CONNECTOR
Contacts 2, 3 and 15 of J1 (Fig.4
-
2, It
em 5) serve as Output Shut
-
Off (SO) terminals. The SO term
i-
nals accept a 2.5V to 15V signal or Open
-
Short contact to disable or enable the power supply output.
The SO function will be activated only when a transition from On to Off is detected after applyi
ng AC
power to the unit. (Thus, in Auto
-
Restart mode, the output will be Enabled after applying