STUDENT GUIDE T-39N/G NATOPS
b. ESS - manual connection of batteries to essential bus with dual gen fail (only to be
selected if auto transfer fails).
c. OFF - disconnects battery bus from paralleling bus.
3. DC gen switches: generators online at 40% rpm provided the Electrical Master is ON,
Fire Pull handle is in, or the Engine Start (ground or air) is off. Positions are ON-OFF-
4. DC MISSION PWR switch:
a. NORM - power to DC mission bus A and B from essential bus.
b. EMER - power to DC mission bus A if single gen failed.
c. OFF - removes power from both DC mission bus A and B.
5. Battery isolation switches:
a. OVERRIDE - Used during 2nd engine start with battery switch off (allows the battery
to start the 2nd engine while the 1st engine generator powers the paralleling bus).
b. ISOL - Removes the respective battery from the battery bus via the isolation relay.
c. NORM - Normal connection of batteries to battery bus.
D. DC power indicators
1. Voltmeter - shows essential bus voltage unless PUSH LH/RH GEN VOLT is depressed.
2. Loadmeter - LH/RH, should be within 1 division (after engine start, up to 30 min allowed
Caution lights single DC GEN OFF - reset ( Gen will kick off line btwn 31-33v)
LH/RH DC GEN HOT - gen OFF (155 C)
BATT HOT - Battery switch off (150 F) ESS BUS CB OUT - extra loads OFF
MISSION A or B FAIL - select EMER if the radar is desired.
E. Single DC Generator Ops
1. Max load on operating generator =
.8 - sea lvl to 30,000'
.5 - 30,000' to 40,000'
2. Maintain .65M for cooling, max op altitude = 40,000
F. AC power source
1. Main or Stdby inverter (1500 or 1250 v-a, 115 + 8 volts)
2. Instrument inverter (1000 v-a, 115 + 8 volts)
ELECTRICAL SYSTEM 3-3