Note: Many of these manufacturers make specialty systems for large data centers, not the consumer-grade UPSes that we cover in most of the rest of this document.
APC is the largest manufacturer of small UPSes (<2000 VA) and has a whole line of UPS systems (mostly line interactive), software, and power system accessories which can be purchased directly from them or via many retail outlets around the United States and overseas.
Belkin makes a lot of computer connectivity products, including UPSes.
Clary sells UPS products and specializes in emergency, military, and life support systems. They also sell management software and accessories.
Controlled Power produces UPS systems, power conditioners, voltage regulators and transformers. Equipment can be ordered direct.
Eaton Powerware includes the product line that was formerly Best Power, Inc.. They produce many types of UPS systems. more advanced line interactive systems, and ferroresonant line interactive systems as well as software, PDUs, and power system accessories.
Emerson is a big electronics conglomerate. Its claim to fame in the UPS world is that it's the parent company to Liebert.
Energy Technologies provides power devices (including UPSes) for physically demanding customers, including military and vehicle uses. Most if their UPS systems seem to fall in the 600 to 6000 VA range.
One of the bigger players in the data center sized UPS system industry, Exide also makes more modest sized on-line and line interactive systems. Exide products can be purchased direct or from their distributors.
We're told these guys are the largest UPS manufacturer in Israel and the Middle East. Their product line runs the gammut from 1000 VA to 150 kVA systems.
Yup, GE makes UPSes from 300 VA up to MVA systems.
Intellipower sells on-line UPS systems and management software.
A subsidiary of Emerson Electronics (see above), Liebert is probably the largest manufacturer of large (10 kVA +) UPS systems. Also well known for their other data center products including power distribution units and HVAC products. They also make smaller UPS systems (300 VA on up), but these are not nearly as popular.
MGE UPS Systems sells UPS systems from 300 VA to the very large and additional power equipment.
Mitsubishi Electric Automation seems to specialize in larger (> 5 kVA) UPSes, but they make them as small as 1 kVA.
Oneac sells line interactive and online UPS systems with software in the US and UK. They were acquired by the Chloride Group (see Chloride Power, below) in 1998.
OPTI-UPS makes standby, line-interactive, and online UPS systems ranging from 375 VA to 8000 VA.
Philtek makes inverters and other similar power system components.
SL Waber sells mostly UPS systems including the Tripp Lite brand name as well as a wide assortment of surge suppression and other power accessories.
Toshiba sells a lot of things, including UPSes. They sell online UPSes from 1400 VA to the 300 kVA range. One of Toshiba's product lines are UPSes specially designed to automatically configure themselves to work with both US (60 Hz) and European (50 Hz) power.
P3 International makes a number of cool consumer electronics devices, but as far as this document is concerned, the most interesting is an easy-to-use and relatively inexpensive power monitoring device called "Kill A Watt". When you can't or don't want to use a good break-out cable and ammeter, this device is a good choice for measuring power consumption.
Power Innovations sells online UPS systems ranging from 500 VA to 400 kVA.
Chloride Power is a relative newcomer to the U.S. market but has much more experience and is better known in Europe. For the US market Chloride produces online UPS from the 700 VA to 3000 kVA range, and what look like they might be standby systems from 300 VA to 650 VA.
There are a lot of companies in this space, and there's no way that we can list all of them. We try to include most of the best known companies along with a few niche players that might be of interest to the readers of this document. Let me know if there are important companies that we haven't included.