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APC BE500R Back-UPS ES 500 (BPAPWBE500R) UPS System - Page 9 Questions & Answers
Pac makes continous sound
What is the sound? Is the device working normally? Are there any lights or indicators? Do they indicate a fault or error?A UPS runs on standard 110-120 VAC power. It converts the input power to DC and charges internal batteries, then back to AC. Connected devices actually run on the conditioned 115-120 VAC output. The batteries serve as a short term backup power source.The electronics in the UPS can produce hum or high pitched tones. The sound should not be annoying. If it is louder than connected equipment (computers) it may indicate a problem. Hum is usually 60 Hz harmonics and difficult to eliminate. This harmonic may be transferred to audio equipment such as speakers or radios. A high pitched tone can be related to the rectifiers for the convertor/invertor. If the tone is loud, it means the rectifiers are drawing a lot of current. This is usually related to bad batteries.Measure the voltage on the output receptacles. It should be 115-120 VAC. Disconnect everything on the output receptacles. Unplug the UPS from it's power source. If the output power dies within 1 minute, the batteries need to be replaced.
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