Operating the Power Supply Locally
3
Series N5700 User’s Guide
41
Over-Temperature Protection
The over-temperature protection circuit shuts down the power supply
before the internal components can exceed their safe internal operating
temperature. This can occur if there is a cooling fan failure. When an OTP
condition occurs, the output is disabled, the display shows O7P, the
PROT indicator blinks, and the OT status bit is set in the Questionable
Condition status register. Resetting the OTP circuit can be automatic
(non-latched) or manual (latched) depending on the Safe-Start or Auto-
Restart mode.
In Safe-Start mode, the OTP circuit is latched. The display continues to
show O7P and the PROT indicator continues to blink. To reset the OTP
circuit, press the OUT ON button.
In Auto-Restart mode, the OTP circuit is non-latched. The power supply
returns to its last setting automatically when the over-temperature
condition is removed.
Power-Fail Protection
If the AC power stops briefly, but returns before the power supply has
reset, the power-fail protection circuit trips and the PF status bit is set in
the Questionable Condition status register. Resetting the power-fail
protection can be automatic (non-latched) or manual (latched),
depending on the Safe-Start or Auto-Restart mode.
In Safe-Start mode, the output of the power supply is Off, as specified by
the reset state when AC power returns. In Auto-Restart mode, the power
supply recovers its last settings when AC power returns.
Front Panel Lock-Out
The front panel controls can be locked to protect from accidental power
supply parameter change. Press and hold the LIMIT button to toggle
between Locked front panel and Unlocked front panel. The display will
cycle between LFP and UFP. Releasing the LIMIT button while one of the
modes is displayed, selects that mode.
In Unlocked front panel mode
, the front panel controls are enabled to
program and monitor the power supply parameters.
In Locked front panel mode
, the VOLTAGE and CURRENT knobs, the
OCP/488 button, and the OUT ON button are disabled
The power supply will not respond to attempts to use these controls. The
display will show LFP to indicate that the front panel is locked. The
OVP/UVL button remains active to preview the OVP and UVL setting. The
LIMIT button also remains active to preview the output voltage and
current setting or to unlock the front panel.
NOTE
This function operates independently of the SCPI SYST:COMM:RLST command.
If the front panel has been locked from the front panel, it cannot be unlocked by
SYST:COMM:RLST. Conversely, if the front panel has been locked by
SYST:COMM:RLST, it cannot be unlocked from the front panel.
