The plant loses power suddenly and a few times Windows failed to boot afterwards. Is there anything short of buying a large UPS?

A cabinet-wide UPS is one option, but industrial computers usually allow something smaller and cheaper. A DIN-rail 24 V buffer: a battery or supercapacitor module feeding only the computer branch, good for a few minutes. It fits in the cabinet and needs no space for an AC UPS. A power-fail signal: most buffer modules provide a contact indicating battery operation. Wire that contact to a digital input on the machine and have software shut down cleanly after a set delay. This is the decisive part — backup power without an orderly shutdown still corrupts data. Some industrial models include vehicle-style ignition power control — switching on a signal with a configurable off-delay, which is exactly this use case. On the software side: enable the write filter (UWF) if the machine runs a single fixed application, keep logs and data on a separate partition, and use an industrial SSD with power-loss protection. Together these three sharply reduce how often a machine has to be reimaged.