Types of Uninterruptible Power Supplies

There are four types of uninterruptible power supplies. Acumentrics’ products are based on the most capable of these four, with added features that allow the units to automatically register and condition irregular or exotic power input. The four UPS types are:

• Standby UPS— the simplest and least expensive, but the back-up battery is not connected into the circuit until a power interruption occurs. At that point a transfer switch closes and the battery supplies power. However, there is an unavoidable momentary loss of power as the switch closes. That momentary loss generally is unacceptable to modern computing and telecommunications equipment. A Standby UPS also does not deal well with voltage sags and low frequency conditions that can occur short of an actual loss of power, all of which can damage sensitive digital equipment.
• Ferroresonant UPS— an improvement with use of a three-coil transformer which acts like a fast switch upon loss of power, but it still does little to cure voltage and frequency problems.
• Line-Interactive UPS— a totally different design than the first two. It uses a continuously on-line battery with an inverter/converter to keep the battery connected to the output. It provides instantaneous back-up, but deals only marginally with voltage and frequency problems.
• True On-line UPS— in this design, all input is converted into DC and then is converted back to AC. All voltage and frequency problems are handled, since all AC input is converted to DC and then back to AC at the proper voltage and frequency. Since the battery is always in the circuit, there is instant back-up. This design is like the system in a laptop computer. The laptop gets its power from the battery. The battery can be continuously recharged from the AC charger. The laptop keeps running uninterrupted even if the power cord is unplugged.

Acumentrics’ units all use the true on-line UPS design, and add the ability to take in both DC and AC and give back both DC and AC. For complex computer and communication systems that require both DC and AC power, customers find this feature very important. In addition, the Acumentrics units can accept power from a wide variety of sources worldwide—AC from 40 to 400 cycles per second and 80-265 volts, plus DC from 22 to 32 volts. The units then can give back pure 50 or 60 cycle AC at 110 or 230 volts, and DC at 12, 24, 28, or 48 volts. Customers appreciate the flexibility of the unit and the fact that they need not carry added converters to deal with exotic power supplies.