Issue

Why is my UPS showing a “Bypass not in range” alarm?

Product Line

Smart-UPS On-Line SRT models

Cause:

This alarm is an informational event triggered by input conditions that fall outside the UPS’s bypass input thresholds, which are narrower than those for online operation. It does not indicate a fault, but rather that the input is unsuitable for bypass mode.

The UPS monitors input conditions using several detection methods. If any of these detect an anomaly, the UPS may log a “Bypass not in range” event. These conditions can include:

• Voltage or frequency out of range
• Distorted input waveform
• Missing neutral
• Phase imbalance
• Short transients or THD (Total Harmonic Distortion)

Resolution:

The cause of these alarms can differ from site to site. To determine the specific contributing factors, we recommend monitoring and recording the UPS input conditions over time. In some cases, alarms may be triggered by high input Total Harmonic Distortion (THD), while in others, they may result from distorted input waveforms or brief transient events that momentarily push voltage or frequency outside the acceptable range. These events can be very short in duration, sometimes lasting only a few milliseconds.

To help reduce the frequency of these alarms, it may be beneficial to review and adjust the UPS Bypass Upper and Lower threshold settings based on the observed input conditions.

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