NAI's Power Monitors are used by commercial aircraft customers such as American, Delta, Singapore, Monarch & China Airlines to monitor input power to aircraft electrical systems during switchover from aircraft to ground based power or when on a ground-based power source to protect onboard electronics & equipment. A switchover of power can cause spikes or phase reversals and missing phases, which can damage expensive onboard electronics. Ground-based power sources in different parts of the world can vary greatly in quality and damage critical components.
NAI power monitors, (Models iPM, PMA and YMA series) "watch over" the voltage and frequency of the input power to ensure that they are within prescribed high and low limits. They also look at the phase sequence in 3-phase systems. NAI power monitors use output relays, which energize and de-energize according to whether the power conditions are in or out of tolerance. These relays are typically used to trigger an alarm so that action can be taken to protect the system from damage.