PowerGuard® FAQ

How does PowerGuard® save you power and money?

PowerGuard® intelligently manages your peak power demand by shifting non-essential loads to periods where the demand is lower. (Basically it evens out the peaks and valleys of your electricity use.)

Most commercial customers pay peak demand charges, and thus a reduction in peak power demand directly leads to a reduction in your electricity bill.

For devices such as air conditioners, PowerGuard® also helps reduce energy consumption, which leads to additional savings on your electricity bill.


How does PowerGuard® work?

Peak demand is the maximum power demand that is required or used over a specified period of time. It is different to the amount of power consumed. Utilities and municipalities usually charge commercial consumers a peak demand charge, because their peak demand determines the amount of electricity that has to be generated at their power plants. For many commercial customers peak charges can be more than 50% of their electricity bill.Peak demand for the day - better quality edited II

The picture to the right helps explain the difference between peak demand and amount of power consumed.

For devices such as air conditioners, PowerGuard® also helps reduce energy consumption, which leads to additional savings on your electricity bill.

powerHere is another look at what peak demand means:

As you can see, whilst the same total energy is used by 1 bulb in 10 hours or by 10 bulbs in 1 hour, the utility has to provide ten times more energy at any moment in time for the 10 bulbs than for the single bulb. This is what is called ‘peak demand’.

For the single bulb, peak demand was 0.1 kW, and for the 10 bulbs it was 1 kW. So just by spreading out the load over time, the peak demand can be reduced dramatically, and thus reduce the number of new power stations that are required to be built. It can also help reduce the need for load shedding.

Most commercial electricity customers in South Africa are charged for peak demand – i.e. the highest peak demand in any 10 or 30 min period in the month determines their peak charge. For many of them peak charges are more than 50% of their electricity bill.

Does PowerGuard® work with standby generators?

PowerGuard® is an excellent companion for standby generator systems. It can automatically switch to a different load profile if grid power is lost, allowing you to operate at lower power supply levels.

PowerGuard® can accommodate stand-by power generators as well as protecting loads against over and under voltage conditions. All units can operate with input voltages of between 180 to 420Vac indefinitely and can withstand 6,000 Volt spikes as well as conforming to regulated EMI standards.

PowerGuard® has secondary settings allowing the consumer to use smaller standby generators than before. You can save on purchase price and fuel. For example, it might be possible to install a 6KvA generator instead of a 15KvA generator when combined with PowerGuard®.

Does PowerOptimal's demand management technology reduce my company's carbon footprint?

Demand management focuses mainly on reducing peak demand, and not on reducing power consumption. For an individual company, implementation of demand management in itself will not have a substantial impact on consumption, and thus the impact on the customer’s carbon footprint will be limited.

The main benefit of demand management for an individual customer is in managing security of supply and reducing cost.

However, where the loads that are managed consist mostly or solely of air conditioners, demand management does also lead to a reduction in consumption – up to about 15%. Thus there is a meaningful impact on carbon footprint in this instance.

Also, there is a significant potential impact on carbon footprint from a national perspective. The utility has to have sufficient installed capacity to supply the highest peak demand, and any reduction in this peak leads to a reduced requirement for capital infrastructure and costly peaking plants that contribute to the national carbon footprint.

Demand management needs to be seen as one part of a company’s approach to reducing its carbon emissions and potential carbon tax related liabilities.

 Terminology FAQ

What is peak power demand and how does it affect my bill?


  • Your total electricity consumption/usage – measured in kilowatt hours (kWh) and
  • Your peak power demand – measured in kVA

There is only so much you can do to reduce your commercial electricity usage, but effectively managing your peak power demand can realise substantial further savings.

Think of it as a highway – at peak times, the traffic bottlenecks, leading to huge traffic jams. Yet at other times, the road is completely empty. Wouldn’t it be great if we could spread out highway-use so that traffic is always flowing but never congested, day and night?

Unfortunately, the only way to make this happen, apart from re-building the highway, is if enough people decide to go work at midnight and at the early hours of the morning. Any volunteers?

But, here’s the good news. With electricity, smoothing out this peak-time “traffic problem” is actually possible. This is called “Demand Management”.

Demand management explanation - traffic analogy


What is kWh?
kWh is a unit of energy. It is equivalent to 1 kilowatt (kW) of power expended for 1 hour.
What is kVA?

A kVA is a 1000 volt amps. It is the apparent power used and is related to kW (real power) by the power factor. A low power factor means that the utility has to deliver more power than is actually required.

What is the load factor?

Load factor is the average power divided by the peak power over a period of time, and is a measure of how constant the power use is. A low load factor means that power demand (the amount of power required at any point in time) varies a lot over time. A high load factor means that demand is relatively constant.

Low load factors mean that utilities have to install more capacity (build more power plants) to cope with the high peak demands and variation in demand. This makes it more costly for them to supply power.

Peak demand for the day - better quality edited II

What is the power factor?

In simplified terms, the power factor is the ratio between the kW and the kVA drawn by an electrical load where the kW is the actual load power and the kVA is the apparent load power that has to be provided by the utility.

It is a measure of how efficiently the load current is being converted into useful work output.

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