Download Portable Appliance Testing Course Pre-Study Revision

Perquisite knowledge before Training and Assessment
Portable Appliance Testing Course Pre-Study Revision
 The candidate will need to understand basic electrical symbols and
measurement units.
i.e.… voltage (V) measured in volts (V),
current (I) measured in Amperes (or amps for short) (A),
resistance (R) measured in ohm’s (),
power (P) measured in watts (W)
 The candidate will need to understand basic numeric prefixes used with
electrical symbols and measurement units
i.e.…
milli (m) a thousandth e.g. 3mA : three thousandths of an amp
kilo (k) a thousand times e.g. 100k : one hundred thousand ohms
mega (M) a million times e.g. 2M : two million ohms
 Basic relationship between current, voltage, resistance and power
The candidate will need to understand the principles of Ohm’s Law:V=IxR
I=VR
R=VI
i.e… In a circuit with a voltage of 230V and a resistance of 46 what
current would flow?
Therefore:then
and
I=VR
I = 230  46
I = 5A
 The candidate will need to understand the relationship between electrical
power, applied voltage and circuit load current: P=IxV
In the above example, for a load current of 5A at an applied voltage of
230V, calculate the power used
If :-
P=IxV
then
P = 5A x 230V
so
P = 1150W
or
1.15kW
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