Current describes the movement of electrons in any medium it passes. It is measured in Amperes, with short form as Amp & symbolized as A.
The best way to understand this is to compare with running water through pipe in your home. The rate of movement of water is current in that case.
Voltage describes the pressure exerted on the electrons (just like water in overhead tank, with pressure from gravity), by what we call potential difference.
Voltage is measured in Volts with V as its symbol.
Power is the action delivered when you have electron current flowing at a rate under a voltage or pressure.
Thus it is a multiplication of Current & Voltage.
Power is measured in Wattage or Watt for short form & represented as W.
In the last installment, we explained the meaning of the basic units of measurement in Electricity, as Ampere for Current, Volts for Voltage & Watt for Power.
In application, these units are used in fractions and multiple & so methods were developed to make it easy to write & manipulate the figures emanating from these.
The common figures and their rating are stated below:
1,000 - Kilo
1,000,000 - Mega
1,000,000,000 - Giga ....and so on.
Thus, we have power rated as kilowatts or 1,000W,
Megawatts or 1,000,000W and so on!
For the Fraction, we have:
1/1,000 - Milli, then gives Milli ampere or Milliamp and so on.
Let us apply what we have learnt so far by using them in our day to day activities.
Now you should understand when they say your transformer is rated 33kv/415 of 500KVA.
This means this Transformer receives voltage at 33,000 volts and step it down to 415 volts (Line to Line) & 240 volts Line to Neutral.
The Power rating is 500,000 Volts-Amperes.
That Volts-Amp is also Watt as explained earlier, but as professionals in this field, we know that there is a little difference between the power ratings of equipment in Watt & VA.
However, for the sake of avoiding confusion & till the time we shall get there, let's see Electrical Power as being measured in Watt.
In our homes we receive 240V (volts), because we are on Live to Neutral connection; on what is termed Single phase.
You may wonder why we are not giving examples from current; well, we have 500mA (Milli amps) or 0.5A, 1A (One Amp), 2A (Two Amps) consumed by various types of phone chargers.
Why we talk less of current is because every device request & consume its own amount of current it requires to perform its function.
So the current a small fan will consume would be less than a Fridge, but the voltage would remain the same for all devices.
QUICK TIPS: Do you ever wonder why some phone chargers charge 'faster' than the other?
Well, when looking for a good charger next time, look out for those once truly rated 2A and see what you get. The ratings are always in fine print.
© Tunde Y. Salihu, 2016