Although voltage sags have the appearance of an insignificant event, it actually causes current inrushes that adversely affect both the operation of electronic equipment as well as component longevity. Most voltage sag events last anywhere from 1 cycle (16 milliseconds) to 10 cycles (0.16 seconds).
The current inrushes occur after this brief sag event. They are caused by the combination of the capacitors inside of the connected equipment discharging and then instantaneously presented with an increase in voltage level during the recovery period.
During this instantaneous voltage increase, a large current inrush is generated. It has been shown in laboratory tests that these instantaneous current inrushes reach 5 to 10 times the normal current draw. Studies have shown that these current inrushes cause damage to both silicon based devices (microprocessors and circuit boards) as well as filter capacitors in the connected equipment’s power supplies.
Most electronic equipment inherently contains current inrush limiting that is used at turn-on for the same reason – to limit the current inrush when voltage is applied to discharged capacitors. However, these built-in current inrush limiters are heat controlled devices and are purposely taken out of the circuit 10 seconds after power up. During a Voltage Sag, these internal devices do not have the time to cool down to provide current inrush limiting.
Figure 1 depicts both the voltage and current readings from an oscilloscope monitoring a typical voltage sag. It is clear that the excess current draw of 45.2 Amps can cause significant harm to any connected electrical components.
Innovolt’s patented circuitry utilizes microprocessor- based LINE monitoring to actively protect against the current inrushes that result from voltage sags by inserting fully reset current inrush limiting circuitry in line with the load before the recovery period begins.
The above figure (Figure 2) shows that the current inrush at the point of recovery from the exact same voltage sag was reduced from 45.2 to 18.8 Amps when Innovolt’s technology was protecting the system. This is a significant improvement in a conservative scenario where current inrush was only two and a half times above the normal current draw of the machine. Many scenarios are much greater in scale and cause much greater damage. The current inrush detection and remediation ability is exclusive to Innovolt.
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