Lockheed C-5M, Technical Manual

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When outside temperature is above 60 °F, do not connect external electrical power to the airplane for more than
15 minutes with the EXT PWR switch OFF and AVAIL light on. Failure to comply will result in inoperative
Electrical Power Control Rack (EPCR) cooling fans and damage to the Bus Power Control Unit (BPCU) may
occur if no other electrical power is applied to the airplane.
w. Place power cart unit switch to on. The AVAIL light (Figure 1-23, 23) on the
À
ight engineer AC ELECTRICAL
SYSTEM control panel should come on.
x. Place EXT PWR switch (22) to ON. External power bar light (24) comes on.
y. On AC ELECTRICAL SYSTEM control panel, ensure the following switches are set:
(1) To NORM:
•
BUS TIE SWITCH 1
•
BUS TIE SWITCH 2
•
BUS TIE SWITCH 3
•
BUS TIE SWITCH 4
•
MONITOR BUS SWITCH 2
•
MONITOR BUS SWITCH 3
(2) To AUTO:
•
AC CROSS TIE SWITCH
NOTE
Cross tie CLOSED light will be defaulted to NVIS (very dim) until core processing system power is applied.
z. Verify that cross tie CLOSED light is on.
aa. Perform a caution light test on AC ELECTRICAL SYSTEM control panel and DC SYSTEM control panel by placing
CAUTION LT switch (Figure 1-25, 1) to TEST at
À
ight engineer station.
ab. Ensure that all bus off lights are off except MON BUS 2 and MON BUS 3. If MONITOR BUS operation is required,
place MONITOR BUS switches 2 and 3 to OVRD until Core Processing is online. (Refer to Figure 1-23.)
ac. Place VOLT SEL switch (3) to RTRU 1. The DC VOLTS meter should indicate 28 (±3) volts.
ad. Place VOLT SEL switch (3) to RTRU 2. DC VOLTS meter should indicate 28 (±3) volts.
ae. Place VOLT SEL switch (3) to ACFT BATT and ACFT BATT switch (11) to BYPASS. DC VOLTS meter should
indicate a steady 28 (±3) volts.
af. Place VOLT SEL switch (3) to APU BATT.
TO 1C-5M-2-1
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