Power in an electric circuit is the rate of flow of energy past a given point of the circuit.In alternating current circuits, energy storage elements such as inductors and capacitors may result in periodic reversals of the direction of energy flow. The portion of power that, averaged over a complete cycle of the AC waveform, results in net transfer of energy in one direction is known as active power (sometimes also called real power). The portion of power due to stored energy, which returns to the source in each cycle, is known as reactive power.Źródło: https://en.wikipedia.org/wiki/AC_power
First of all, the problem can occur in drives to the gates, which may not respond to user requests or for example open instead of closed.
An electric power system is a network of electrical components used to supply, transfer and use electric power.
Smaller power systems are also found in industry, hospitals, commercial buildings and homes.The majority of these systems rely upon three-phase AC power?the standard for large-scale power transmission and distribution across the modern world.
Specialised power systems that do not always rely upon three-phase AC power are found in aircraft, electric rail systems, ocean liners and automobiles.Źródło: https://en.wikipedia.org/wiki/Electric_power_industry.