Students, in the world of prepaid systems, there are many options. There are options for equipment, software, networks, systems and so on. But, there is one area where there are few; something so vital you cannot exist without it. Power. Think about it, without power, you are out of business. The best news is that most power outages are very short in duration. Typically, just long enough to throw your system into chaos.

While the impact of power outages on my television setup is a personal annoyance, the impact of power glitches can be downright devastating to a prepaid business, or any business, for that matter. Resetting the clock on the VCR is annoying, but rebooting a server can represent significant down time. A lot of these hiccups can be taken care of easily, with some simple and inexpensive strategies.

There are several layers of power protection, so let’s look at them in order from the simplest to most complex.

First, are surge suppressors. While very worthwhile, they offer minimal protection. Their only real function is to suppress voltage spikes. These very short, 5 millisecond or less surges in voltage occur frequently. Some electronic equipment has internal components to deal with them, but a surge protector can prevent a lot of problems before the spike even gets to the equipment. Surge protectors are cheap, and can handle large loads, so big equipment, like copiers and monitors, can also be protected with them. But, they will provide no help in dealing with power outages of any duration, no matter how short; all they do is suppress a high voltage spike.

The ultimate in power protection are Uninterruptible Power Supplies, which can provide backup power in the event of a power outage. Do you know that nearly all, well over 90%, of power outages are less than a minute long? Just enough to turn off your POSA device, PC or telephone system. Very disruptive. And Murphy’s Law tells us that these outages are always going to happen at the worst possible moment. Fortunately, there are relatively inexpensive UPSs that will deal with these.

A UPS is very simple in concept. It is plugged in between the power outlet and the device, like your PC. In addition to surge suppression, it continuously monitors the power for indications of power glitches. When the power is about to go out, there are indications on the Alternating Current waveform that indicates an outage is imminent, even if the switch is turned to the “off” position. The UPS detects these anomalies, and instantaneously switches off the AC power, and kicks in its internal battery and inverter. The battery and inverter put out an AC current that is identical to the power from the good ol’ power company. The good news is that the price of a UPS has dropped dramatically, making them an inexpensive addition.

To decide on how big of a UPS to get, you need to have an idea of the power drain of the equipment you are going to support. A UPS is rated in two main ways. The first is the load. This is measured in Volt Amperes, VA, and is calculated simply by multiplying the voltage, 120 volts here in the US, by the current in amperes. If you look at the back of the equipment, it should have this information. For example, a typical PC might say 3 amps. This is a maximum figure, and the actual drain might be somewhat less than this. One word of warning, devices like CRTs, laser printers and copiers have instantaneous power needs that could be quite high. For example, a laser printer might draw about 2 amps in operation, but when the fuser is heating up, it could be as high as 5 amps. These devices should usually not be included in the UPS unless absolutely necessary.

So, you add up all these devices and that will tell you how big of a UPS to get. A typical PC with peripherals might need 350-500 VA, so a lot of UPSs are in this range. Smaller devices, like a POSA terminal, are going to be a lot less, and there are UPSs that are like big power strips that will work fine. Same with telephones and other small devices. Remember that you do not have to put everything on one UPS, so if you have two PCs, you can put each one on its own separate UPS.

The other criteria is the amount of time that you can operate on the UPS. This is a function of battery size, so as a rough rule of thumb, the heavier the UPS, the longer it will operate. Typical holdover times are 10 to 30 minutes or more. Even at the low end, you will cover the vast majority of outages. If you have a history of longer duration outages, you will need to find a UPS with a lot of battery capability. There is a very easy way to determine how long a UPS will hold up; just disconnect the power while it is operating, and time it. Many UPS’s come with software that will refine this process a great deal. It is recommended that you periodically test the UPS by pulling its power cord from the outlet, to make sure that everything continues to operate.

The big issue for a PC is the CRT. It creates several issues. First, when a CRT is first turned on, there is an inrush of current that could trip the circuit breaker in the UPS. Even then, the CRT takes a lot of power, often as much as the PC itself. This will cut in half the backup time. One way to deal with this is to NOT plug the CRT into the UPS. If you do this, you will probably not be able to use the PC since you can’t see anything, but the UPS will hold up a lot longer. Your exact situation will dictate if this is a viable alternative. 

If you have an LCD monitor, it will draw a lot less current, so it will last a lot longer. LCDs also do not have the initial inrush, so you will avoid this problem as well. Or, if possible, use a laptop instead of a PC. This has the added bonus of an internal battery that will power it for 1 to 8 hours. If plugged into a UPS, even a small one, you will be good to go for a long time.

Our intent here was to treat the power situation as regards to an office, or a small retail location. If your requirements are more stringent than that, you will have to look at larger scale, and more expensive, solutions. But, for a POSA and/or retail front-end operation, the new breed of UPS can be the answer to a very serious problem.

See you next class.