SOLUTIONS:
Sustained Low/High Voltage
 

Sustained low or high volts carries operational and maintenance issues. Here we show some of the standard cures for this.

SUSTAINED HIGH VOLTAGE

THE PROBLEM:
One of the most common problems with sustained high voltage is short life of incandescent lamps, motor burn-out, but the most unseen damage is electricity bills. With electricity suppliers pushing the voltage up a little in order to get a quicker return on their purchases (they don't like me saying this!), users can 'fight back' by bringing it down again to more realistic levels.

Lowering the voltage to a domestic property is not extremely effective at cost saving as cookers, immersion heaters, and kettles still need the same energy to heat water and food (a lower voltage will simply have an added annoyance of the heating process taking longer).

However, lowering the voltage on selected circuits, such as a lighting circuit, can have a dramatic effect. In this case it would lengthen lamp life, but also have a relatively high impact on energy bills too as lamps tend to be the item most used in a home.

Although it has proved to be less effectual in a domestic property to reduce the incoming voltage as the energy used to heat anything still remains the same, reducing the input voltage to an industrial premises does not hold the same restriction.

Most industrial and commercial sites mainly use power to provide lighting with very little being used to provide heating energy on a large scale. It must also be remembered that power used will closely resemble the V² rule so a reduction of just 5% could result in close to a 10% reduction in power use! And, by reducing the power use, the heat losses are also reduced meaning the cooling system does not have to work as hard as it did - I make that "doubled energy saving"!

Some quick maths. An entertainment site using 250A per phase will consume approximately 183kVA at 245VAC. Dropping the voltage by a mere 5% will drop the power use by 10%. 18.3kVA by 12 operating hours per day by 364 operating days a year at 6 pence per kWh will save approximately £5000 per year!

This figure does not take into account related savings such as longer lamp life, reduced operating wear on machinery, and, as said earlier, lower cooling costs as heating losses are significantly reduced. And, to put the cherry on the top, there is now added protection against extreme voltage input.

THE CURES:
There are two cures for sustained high voltage. The first, however, is really only open to those who are fed from their own transformer. This can be "tapped down" to a more suitable voltage. As it is a dedicated supply, there is no chance of affecting a co-user who may just want the voltage to "stay in the clouds".

By the way, if the local electricity supplier are the ones who have to tap down the transformer, expect some opposition (if not a lot) to this move. They are well aware that by reducing the energy bill, their profits take a hammering too!

The second cure is the "Auto-Transformer", this being featured in the next page.

Please do note: Although I am clearly for lowering the voltage, I do question the validity of dropping the voltage to levels shown in some marketing material.

In all cases, it is vital to have a voltage survey done first to ensure that once the tap change on the transformer is complete, that there is not going to be a time when the voltage will fall too low to efficiently start motors and other devices that require a minimum start voltage (some fluorescent lamps are sensitive to this). With low voltage, incandescent lamps will have a higher infrared vs. usable light ratio as the filaments will not be running at their designed temperature.

My belief is to aim for a mean of 230VAC to get the best of both worlds.

Auto-Transfomers  >>