Xnet Solutions: The UPS FAQ.
Q. What is an UPS?
A. An Uninterruptible Power Supply is a machine that is placed between a power supply (i.e. Your local Electricity Power Supply Company or your own generator) and a device (e.g. a PC or server) to stop undesired features of the power source (power loss or brownout, voltage surges, bad harmonics, etc.) from the supply from harming the device permanently or affecting its performance temporarily .
Q. What is the difference between Near Sine wave and Sine wave?
A. Sine wave is required only for inductive load, like motors, water pumps and fans. Computers and monitors are quite happy with near sine wave or even flat line DC. If you use near sine wave for inductive load then there is some noise and heat generated. You should never use DC for inductive loads.
Q. What kind of UPS are available on the market and what type is the PP2100DC UPS
A. There are 3 kinds of UPS available:
[1] Invertor. These are the cheapest and require manual switching;
[2] Off line. These provide relay based switching and will cause some PCs to restart. High speed processors are more likely to rebot than older machines. Offline UPSs are based on invertors;
[3] Online. There is no switching involved. Online UPS will always provide clean output power from the battery. You will never get power directly from the power company. The PP2100DC is a true Online UPS.
Q.What does VA Mean?
A.The VA rating is the maximum number of Volts x Amps it can deliver. The VA rating is not the same as the power drain in Watts of the equipment connected to the UPS. 1000VA is about 707 Watts. If you want to get technical then the conversion is derived using the root mean square, discussion of which is beyond the scope of this FAQ.
Q. What Power do we need for my network of 10 computers?
A.
If we assume that a PC uses 150W as a minimum and 400W at maximum then we have:
( 10 x 150W ) + (2 x (400W -150W))
= 1500W + 500W
= 2000W which is about 2857VA.
So you need 2857VA.
The PP2100DC will support these 10 PCs for 1 hour.
Q.What is a Blackout ?
A.This is a complete loss of power.
Q.What is a Sag or Brownout?
A.A brownout is a decrease in voltage levels which can last for periods ranging from fractions of a second to hours. This can be caused by heavy equipment coming on line such as air conditioners, elevators, compressors etc. Also occurs when utility companies deliberately do this to cope with peak load times or when there are problems with the power lines. The PP2100DC will keep recharging its batteries even during brownouts.
Q.What is an electric voltage Spike?
A.A very very large increase in voltage over a very short period of time often caused by a direct lightning strike on a power line or when power returns after a blackout.
Q.What is a Surge ?
A.An large increase in voltage lasting a small fraction of a second, often caused when high powered appliances such as air conditioners or heaters are switched off.
Q.What is an Inverter?
A.An Invertor is circuitry that converts DC battery power to the AC power that is required by most computer and networking equipment.
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