Different types of UPS design

- Apr 01, 2021-

There are three general categories of modern UPS systems: on-line, line interactive or standby/offline.

standby/offline UPS system the load is powered directly by the input power and the backup power circuitry is only invoked when the utility power fails. Most UPS below 1 kVA are of the line-interactive or standby variety which are usually less expensive.

line interactive UPS maintains the inverter in line and redirects the battery’s DC current path from the normal charging mode to supplying current when power is lost.

An on-line UPS uses a “double conversion” method of accepting AC input, rectifying to DC for passing through the rechargeable battery (or battery strings), then inverting back to 120V/240V AC for powering the protected equipment.

For large power units, dynamic uninterruptible power supplies are sometimes used. A synchronous motor/alternator is connected on the mains via a choke. Energy is stored in a flywheel. When the mains power fails, an Eddy-current regulation maintains the power on the load. DUPS are sometimes combined or integrated with a diesel-generator[clarification needed], forming a diesel rotary uninterruptible power supply, or DRUPS.

A fuel cell UPS has been developed in recent years using hydrogen and a fuel cell as a power source, potentially providing long run times in a small space.

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