What specifically are those so called “parasitic or vampire” loads?

“Vampire” or parasitic loads are the electric energy that is being consumed by your appliances while it is turned-off but still plugged in the socket. Technically, these “vampire” load indeed exist and inherent to some of the appliances or equipments that are used not only in the house but almost all of the electrical equipments in the power system. In electrical term, we simply called this as energy loss.

But what specifically are these parasitic or “vampire” loads?
Most, if not all, of the “vampire” loads are due to the energy losses in the appliance’s or equipment’s transformer. In appliances, transformers are used to step down the voltage either to safer usable level or prior to the conversion of the electricity from AC to DC – electricity supply in the household is usually 220 V AC but electronics gadgets require DC supply.

Transformers, whether it is used in high voltage application or in household appliances, have basically the same construction. And transformers, as most of electrical engineers would know, have two inherent energy losses when it is used. One is the copper loss (load loss) which is due to the flow of electricity from source to the output; and the other one is the core loss (no-load loss) or the loss due to the magnetization of transformer iron core and due to the eddy current loss. Unlike copper loss, core losses is not a function of the load and remained constant as long as the transformer is connected to a power supply – even without load; and this is where the “vampire” or parasitic load came from. In my point of view, the “vampire” load is, essentially, the core or no load losses in the transformer. The amount of core loss varies depending on the size and design of the transformer but in large transformers, this could go to around 0.1% of the total capacity. If this would be true for appliances’ transformer, a 500 Watts appliance that is turned-off but still plugged would consume 0.5 Watthour of electricity hourly or 12 Watts of electricity daily – definitely, a waste of energy.

Some of the energy efficiency advocacy groups, campaign on the promotion of energy efficiency by reducing the so called “vampire” loads by doing the habit of removing the plug once an appliance is not in use.

Would there be appliances that have no “vampire” or parasitic load?
Of course, there would be some; these are the appliances that do that have transformer. To list some;
• Electric Fans
• Washing Machine
• Air conditioner
• Electric Stove

Please make sure that these appliances sited above do not have light indicators or monitors because it might still have transformer in it and thus still consume “vampire” loads.

Filed in: Energy Efficiency
Local date: March, 2010

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