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Those of us who are used to the high standard of electricity utility supplies in the industrialised world sometimes forget the problems faced by users of high tech equipment in the third world. This page describes a strategy for planning electrical power protection in a small business or professional office application. These notes may also be helpful to householders facing regular damage to electrical equipment - even just ordinary light bulbs.
These fall into different categories the critical load must be protected from one or more of the following:
out of tolerance voltages (sags surges and brownouts)
spikes on the line
and/or keep working when
out of tolerance voltages occur
mains supply fails.
Most electrical equipment is able to function normally if the voltage varies by less than ±10%.
Modern equipment is also usually able to operate satisfactorily in an environment where small noise spikes (less than 100V) arrive down the line.
However the data handled in modern digital equipment is sometimes corrupted by severe spikes.
Some of the equipment may be so critical that it needs protection from both noise spikes and power failure.
Other equipment may need protection from brownouts and/or very high voltages.
A thorough survey of the various equipment loads around the business or office location should be prepared.
Each equipment needs to be classified. For example - critical essential non-essential.
The actual load of each item needs to be expressed in watts.
It is often misleading to take electrical ratings from external labels on the equipment to be protected.
Fuse ratings can also be much higher than actual consumption and should only be used as a guide where no measuring equipment is available.
Separate lists need to be made for the various loads showing which ones are critical and others which just need protection.
Consideration should be given to the possible need for a few lights to be supported when the mains fails so that critical equipment (keyboards!) can actually be seen.
Attention needs to be paid to the problems of separating the various electrical wiring circuits.
It also makes sense to adopt some procedure for ensuring that the load is not used on the wrong supply.
Typical approaches include labelling or the use of different style plugs and sockets.
For some systems permanent wiring is sometimes an alternate solution.
For more information or assistance in preparing a strategy please ask our sales office.
Load |
Watts |
Protection equipment |
| light bulbs TV video freezer hi-fi |
300 75 450 200 625 |
Advance power monitor disconnects the load when voltage goes outside predetermined limits |
| air conditioner |
3000 |
tapping voltage stabiliser to maintain or APM as above |
| digital GSM phone |
100 |
Advance low impedance power conditioner prevents spikes getting to the phone memory |
| fax machine for incoming orders |
150 |
uninterruptible power supply brownout protection and batteries when mains fails - specify backup time |
| personal computer with data which is essential |
450 |
UPS noise spike protection brown out protection + must be protected and batteries when mains fails - specify backup time |
| laser printer modem scanner |
1200 40 120 |
Advance GT power conditioner noise spike protection brown out protection from mains supply these un-essential items go off when power fails |
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