ECN | Define: Frequency and Cycle for AC quantities. | Define: Apparent and Reactive power.

(i) Frequency: 

It is defined as number of cycles completed by an alternating quantity in one second.  

(ii) Cycle:  

A complete set of variation of an alternating quantity which is repeated at regular interval of time is called as a cycle.

  OR

Each repetition of an alternating quantity recurring at equal intervals is known as a cycle. 

(iii) Apparent Power (S):  

This is simply the product of RMS voltage and RMS current. 

Unit: volt-ampere (VA) or kilo-volt-ampere (kVA) or Mega-volt-ampere (MVA)  

(iv) Reactive Power or Imaginary Power (Q): 

Reactive power (Q) is given by the product of voltage, current and the sine of the phase angle between voltage and current. 

Unit: volt-ampere-reactive (VAr), or kilo-volt-ampere-reactive (kVAr) or Mega-voltampere-reactive

(MVAr)