Average Reviews:
(More customer reviews)I own two XS-1000 and one XS-1500 Back-UPS units (also use BX1000 and BR1000 designation). Each is in service, with the XS-1000 units loaded to about 250 watts and less than 300 VA and the XS-1500 loaded to 500W/600VA. Each of these units has failed with symptoms like those described by other writers (overload light suddenly comes on and cannot be reset normally). Unlike the other writers, I repaired my units myself. Yesterday, one of the 1000 units failed again, repaired again, same problem ...
It is significant that I live in a region experiencing frequent power fluctuations and outages, hence need for a backup UPS. It is also noteworthy that circuit boards and circuit designs are essentially identical for the 1000 and 1500 models, with extra battery connections and a fan being prominent additions for the 1500 model.
In all instances, one or more of the six simulated sine wave switching FET transistors (34N20, IRF640B or similar 20NQ20) failed shorted. This, incidentally, correctly causes the overload indicator to come on, since the on-battery circuit is then definitely overloaded! This protective action in fact saves major parts of the unit from further damage, including battery overheating and possible explosion.
Qualitatively, the APC units are very well constructed and seemingly well designed. Additionally, the 34N20 FET transistors are a good choice for this application, and thus the failures are surprising. Several possibilities are suggested: (1) There is a latent quality defect in the transistors. Once one of the six fails, others will fail quickly until the DC/DC inverter stored energy is dissipated; (2) A momentary under or over voltage condition causes the AVR autotransformer circuit to switch in at about the same time the unit attempts to go on battery, possibly resulting in energy stored in the transformer being dumped into the 34N20 switching bank and exceeding a transistor's surge capacity; (3) One of the relays sticks or AVR/backup relay combinations "make before break" during a momentary utility outage or glitch.
Whatever the cause, it seems evident based on my three (now four) unit failures and those similar ones reported by other writers, that this defect, though perhaps infrequent for most customers, is nevertheless an issue for potential buyers who most need backup protection.
APC telephone representatives, though friendly, are not very helpful; the company is unwilling to provide a circuit diagram or even a block diagram of their products. Shipping costs are high even if the unit is still in warranty. Until this defect is acknowledged and corrected, these otherwise attractive units may not be suitable for use under the very conditions for which they were designed.
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Back-UPS RS 1000 Battery Backup System
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