Frequently Asked Questions - UPS
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What is a UPS? Tell me more about the mains power supplied to my computer What can go wrong with the mains power? Why do I need a UPS to protect my computer system? What happens when the power returns? What happens if the power fails when I am not there? Can the UPS shut down the computer system automatically? How much back-up time can I have? Do I need to buy a UPS for every computer? What is a UPS? No it's not a delivery company; the initials stand for uninterruptible power supply. It's basically a battery back up for computer systems. A UPS does two things, it cleans the mains power before it gets to the computer, and provides a battery backup for computers and other critical equipment when the mains power fails. Back To Top Tell me more about the mains power supplied to my computer Mains power is supplied in the form of alternating current (AC). On an oscilloscope it looks like a uniform sine wave. The PSU (power supply unit) inside the computer converts this to direct current (DC), to supply the various components of the computer. Back To Top What can go wrong with the mains power? There are 9 major power failure problems that can occur. These are: 1. Mains power fail. This can be either within an office building, or from the local sub station. 2. Power sags. This is where the mains power drops too low, briefly. 3. Power surges. This is where the mains power moves too high, briefly. 4. Brownouts. This is where the mains power drops too low, and stays there for a measurable amount of time. This can be observed easily, as this condition causes the lights to dim. 5. Line noise. This is often caused by radio interference; it adds spikes to the sine wave form. 6. High voltage spikes. 7. Frequency variation. Can be caused by using a local generator for a power supply. 8. Switching transients. A step in the sine wave. 9. Harmonic distortion. Where the sine wave goes out of shape. Many of these problems are caused by switching on, (or off), any kind of electrical equipment. Electric kettles, laser printers, photocopiers, industrial machinery, lighting, etc can all have an effect on the mains power. Sometimes this is so minor as to be undetectable, often it is just irritating, and in some rare cases can be so severe that it can cause major havoc to the running of an operation. Back To Top Why do I need a UPS to protect my computer system? The power supply unit in the computer is not perfect, and in some cases, will pass on the power fault through into the computer. This is when component failure can occur, bad blocks appear on hard disks etc. In the event of a power failure, a UPS will continue to supply clean power automatically, from it's batteries. This will give the operator time to save files, and shut down in an orderly manner before the batteries become exhausted. Back To Top What happens when the power returns? The UPS automatically passes back the power supply to the mains, and recharges it's batteries. Back To Top What happens if the power fails when I am not there? The UPS will supply power until it's batteries are exhausted. The UPS will then switch itself off until the mains power returns. Back To Top Can the UPS shut down the computer system automatically? Yes, using UPS monitoring and shut down management software. This is usually supplied free with the UPS, depending on the operating system. Communication to and from the UPS is either through a serial communication, or across the local area network. The power coming in, the power going out, and the state of the UPS can all be monitored using this software. For shut down, the UPS sends an 'on battery' signal to the computer, which is picked up by the software. This starts a timer for computer shut down. Messages are broadcast to warn users to log out, and in the final minute, users are normally prevented from logging in. Finally, the computer executes an orderly shut down. The time between power fail and computer shut down is pre set within the software by the in house system manager. Back To Top How much back-up time can I have? As long as you want. A normal UPS is configured for 5 to 10 minutes back up time. By adding additional batteries, this can be extended to several hours. Back To Top Do I need to buy a UPS for every computer? This depends on the critical nature of each computer, and the budget constraints. A UPS comes in a huge range of sizes, from the small shoe box size unit to support one computer, through a mid range section which will support a computer room, server farm etc., to the largest units which can be something the size of 4 or 5 telephone boxes stuck side by side to support a whole building. Deciding which UPS configuration fits your organisation is where we come in.Contact Us Back To Top