Final answer:
If the APU is not available, the batteries will supply power to the Essential Buses during an ELEC EMERG ABNORM for a limited amount of time.
Step-by-step explanation:
If the APU (Auxiliary Power Unit) is not available, the batteries will supply power to the Essential Buses during an ELEC EMERG ABNORM (Electrical Emergency Abnormal) for a limited amount of time. The duration of power supply depends on the capacity of the batteries and the amount of power consumed by the Essential Buses.
For example, if the batteries have a capacity of 100 ampere-hours (Ah) and the Essential Buses require a consumption rate of 10 amps, the batteries would provide power for 10 hours (100 Ah / 10 A = 10 hours).
It is important to note that the actual duration may vary depending on various factors such as the efficiency of the batteries, the condition of the electrical system, and any additional power demands during the ELEC EMERG ABNORM.