If I turn OFF the power meter, then turn in ON will the previous zero/cal information still be good?
The E4416/7A and E4418/9B power meters will turn ON in the same state as when the AC power was turned OFF: with all of the same settings and configurations. This includes the any zero/cal that was done before the AC power was turned OFF. But it is recommended that a zero/cal be performed after the AC power is cycled, but not required.
The N1911/2A power meters do not save the zero/cal information during an AC power cycle for any power sensor. They also do not power ON in the same state as when they were powered OFF. These power meters will turn on in the Preset Default state. To allow these power meters to go to the same state as before the AC power was turned OFF use the Save/Recall feature. The Save/Recall states do not save the zero/cal information. A new zero/cal is required.
With the P-series power sensors (N1921/2A) with the N1911/2A will automatically zero and cal upon AC power up. So zero/cal is not an issue with these sensors.
The N1913/4A power meters also act as the N1911/2A power meters: they start up in a Preset Default state with no zero/cal information. However these power meters also have a Warm Start state function. If the Warm Start state is turned on, then the power meter will start in exactly the same state as it was when it was turned OFF or lost AC power. This includes the zero/cal information. But it is recommended that a zero/cal be performed after the AC power is cycled, but not required.