Introduction Electrical utilities use reclosers on medium voltage supply to isolate faults caused by events such as lightning strikes, tree branches across lines, or animals making contact with live wires. The result of a recloser operation is a momentary power outage, lasting for up to a few seconds. These outages can cause an unplanned production stoppage which can be very costly. When momentary outages occur, energy storage is required. Usually, the plant will have backup generators to provide power during a power interruption. However, the momentary outage and generator synchronization duration are generally not fast enough. The AVCRTS bridge the time gap during the energy transfer or generator synchronization with the load. Additionally, the AVCRTS will also provide backup power during short interruptions that are too fast to start up a generator.
Active Voltage Conditioner Ride-Through System (AVCRTS) The Active Voltage Conditioner (AVCRTS) is an inverter-based system that provides voltage sag and blackout protection. The AVCRTS is specifically designed for
industrial loads and is a single-conversion UPS. Industrial limitations refer to frequent high inrush currents, harmonic currents, and poor power factors.
How the AVC Works The AVCRTS is an offline device and comprises an electrical storage power source, either batteries or super-capacitors, with IGBT inverters and a static switch to connect to the utility. The static switch is closed under normal conditions; this is the standby mode. When the utility voltage drop below a preset threshold, typically 90% of
nominal voltage, the static switch opens in less than ¼ cycle and powers the energy source via the inverter to the load.
When the source voltage is restored, either from the utility or from a generator, the AVCRTS will synchronize the load with the supply, close the static switch, and the inverter will revert to standby mode. In the case of hardware failure or during maintenance, the load current will be automatically transferred to the safety maintenance bypass switch. See
the AVC product offering when only voltage sag protection is required. Why not use a commercial UPS Industrial loads are often associated with high power consumption, specifically with high inrush currents caused by starting of large motors. Inrush currents can exceed six times normal full load currents. Power electronic loads such as rectifiers and VFDs can produce a wide range of harmonic currents. Conventional double-conversion UPS devices may need to be derated to come up with these situations. The AVCRTS static switch and inverters are designed to handle high inrush currents and environments with high harmonic currents.
