Electrical Engineer Interview Questions - General Electrical Terms


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Electrical Engineer / Electrician Interview question
General terms used in electrical engineering
Inrush Current

This is the peak current that occurs when power is first applied to a unit. It is measured in peak amperes

Power factor

This is the relationship of the actual power usage to the apparent power usage.
For example :
Actual Power = 100 watts of power when averaged over a period of time.
Apparent Power = RMS Current X RMS Voltage.
RMS Current = 1.28 A
RMS voltage = 120Vac
Apparent Power = 1.28 A x 120 Vac
= 153.6 VA
Power Factor = 100 watts/153.6 VA
= 0.651 or 65.1%.

True RMS current
The acronym RMS stands for Root Mean Square. The definition of Root Mean Square is the square root of the mean square of the variable values taken throughout one cycle.

Peak current
This is a measurement of the normal running current, but instead of an average or RMS value, the peak value is given. This is the highest value that the current reaches during a given half cycle.
A typical load of the rectifier/capacitor-input type.

Watts
This is the integral of the instantaneous voltage multiplied by the instantaneous current over a half cycle.

BTU/hr
BTU/hr stands for British Thermal Units per hour. The British Thermal Unit is equivalent to the quantity of heat necessary to raise one pound of water one degree Fahrenheit (at 39.2°F). It provides a measurement of power converted to a form that is useful for sizing heating and cooling systems.