2.2 DPU Power System
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The POWER SELECTOR switch is on the power tray panel inside the DPU
enclosure at the rear. It is a toggle switch that must be pulled out slightly
before it can be moved. It has three positions.
LOCAL (middle position): Allows the DPU to power up independent of
the server.
OVERRIDE (straight up): Allows the DPU to power up regardless of
other conditions.
REMOTE (lower position): Not used.
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Two circuit breakers are on the outside rear of the DPU power tray and are
shown in Figure 2–4.
The rocker switch next to the power cable is a circuit breaker that is ON
when it is UP. The circuit breaker is rated at 30 A for the DECmpp 12000
and 15 A for the DECmpp 12000–LC. The amber lamp above the rocker
switch indicates there is power on both sides of the circuit breaker when
it is lit.
The small rocker-type breaker controls the current to the circuits
controlling the power sequencer. The amber lamp above the pushbutton
indicates that there is power on both sides of the breaker. The breaker
trips when it detects loads of more than 1 A. Push it in to reset it.
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The power status indicator on the DPU left front panel indicates the condition
of the power supplies.
Yellow during power supply ramp-up
Green when all DPU DC voltages are correct
When you first turn on the DPU, this indicator is yellow for approximately 3
seconds, then turns green. If it remains yellow, there is a power malfunction.
•
A heat sensor shuts down all power supplies if it detects excess heat. The
power status indicator changes to yellow. After cooling, the power supplies
do not start again until the keyswitch is switched to OFF and then back to
ON or DIAGNOSTIC. An indicator on the power tray also indicates excess
temperature.
•
When the DPU is turned on, the power sequencer turns on the -5 V power
supply and verifies its correct operation before turning on the +5 V power
supply. During this period (approximately 3 seconds), the power status
indicator is yellow. When the sequencer turns on the +5 V power supply, the
power status indicator turns green.
If the power status indicator remains yellow, the powerup sequencer did not
complete its sequence successfully. If this happens, switch the keyswitch to
OFF and then back to ON or DIAGNOSTIC.
2–6 DPU Controls and Indicators
