Saturday, April 27, 2013

The Ups: a thought or two.

A Ups short for interuptable power supply is to condition electricity for the equipment connected to the unit. Usually not all lines are used for that. Some of the power receptacles (where you plug in things) can be used for surge protection only.  Usually the conditioned power receptacles  will say they are for using battery backup and surge protection.

Since I mentioned the unit is for line conditioning, the ups will smooth out or clean the power coming in the the devices the ups protects. It also should protect against extreme situations such power surges and brownouts.

Most people know about power surges, such a protection against such dangers as lightning strikes. Generally that is true if the lightning strike is not a direct hit to your power lines. Some electricity companies will install special surge protection on a home or building making it not usually necessary to have to use surge protectors in the building.

What a lot of people do not know about is brownouts. Sometimes this is called the silent killer of equipment. Surge protection will not help you in protecting from the brownouts. Brownouts can be more problematic than blackouts to delicate electronic equipment in some cases. Brownouts are defined as extended periods of voltage drop or sag coming from the power grid. In brownout conditions, most devices will continue to run, but with unexpected errors and possible long term damage to components. Brownouts can occur at the utility level like blackouts, but in many cases they can also occur within your building’s electrical grid, when a large local load is applied.

In a brownout, power supplies need to draw more current to compensate for the lower supply voltage, which is very stressful for transistors, wires, diodes, etc. They also become less efficient, which makes them draw even more current, aggravating the problem.

The ups obviously has a big job to do. There are actually two basic types of ups's. One unit uses line power till the power goes out and then the battery takes over. The switching from the line power to the battery can leave a short time when equipment connected to the unit has a mini blackout which can cause problems for really sensitive equipment. Plus the part of the system that does the switching will eventually wear out.

The second type of ups has power always coming from the battery via an inverter . The line power via a power regulator keeps the battery charged as needed. In this case, no real switching needs to be done. That is an over simplication, but the power will or should be rock solid.  Generally these types of ups' are more expensive.

Given you just a thimble full lof information. You need to check out any ups that you might want to use in detail. But at least you have a bit of information to start with.

----------------------------------------------------------

Update: Interface from rs232 To apc cable if you do not have usb on your ups for use with the Powerchute software..
 
Adapter cable for the APC  rj45-rs232 cable
The jack in the UPS may be easily use a 8 pin RJ45 connector. It is easy to construct the cable by cutting off one end of a standard RJ45-8 ethernet cable and wiring the other end (four wires) into a standard DB9F female serial port connector. (Try these pin-outs at your own risk.)
PC SignalPC pinUPS PinUPS signal
RxD22TxD
TxD38RxD
GND57Ground
FGShield4Frame Ground


You will also need a special adapter if you do not want to do any soldering. And a DB9 male to male gender changer may also be needed.