01 Jan 2018

Engineering Forumlae

Quantity Symbol Unit Symbol Example
apparent power S Voltage x Current VA 120kVA (1000 x V x I )
current I Ampere A  
efficiency η per unit   0.95 (i.e. 95%)
frequency f Hertz Hz 50 Hz
poles p number   2 pole, 4 pole
pole pairs pp number   4 pole is 2 pp
active power P Watt W kW = 1000 x W
power, input Pin Watt W  
power, output Pout Watt W  
power factor pf per unit   0.86
reactive power Q Voltage x Current reactive var  
slip s per unit    
speed N revs per minute   Not SI unit
torque T Newton . metre Nm  
voltage V Volt V  

 

Quantity DC AC 1 Phase AC 3 Phase
Current (I)
Efficiency
Power Factor  

Formula

Quantity Formula
Fan load power
Fan load power

Ohm's Law

(Resistive circuits)

Power (kW)
Power (Hp)
Power Factor
Pump load power (Hp)
Pump load power (kW)
Slip, s,  (p.u.)
Slip,  (%)
Synchronous speed, NS,  (rpm)
Torque (N.m)
Torque (lb.ft)

Related topics

×

Codes of Practice 2025

IMPORTANT:

The AEMT Codes of Pracice are being replaced with our provisional codes of practice at the end of 2025. Members will be asked to demonstrate compliance with these codes by 2027. The Secretariat and Council are preparing for this transition, ensuring members have the support, resources and tools needed to comply.

Find out more