Which of the following statements regarding efficiency of electrical machines are true?(i) efficiency should be calculated by measuring output and input(ii) efficiency is maximum when constant losses = variable losses(iii) electrical machines are designed to have maximum efficiency at full load(iv) electrical machines are designed to have maximum efficiency at near about full load(v) efficiency should be calculated by measuring their losses(vi) efficiency is maximum when constant losses = x times of (variable losses)

Rating and Loss Dissipation topics include: Losses and efficiency, machine ratings and loss dissipation. An electrical machine's rating is the maximum capacity it can operate at. The rating plate lists the numerical values of electrical and mechanical quantities, including: Power rating: Specified in apparent power (KVA or MVA) Power factor (PF): The nominal power factor for other ratings Insulation class: For the primary coil Type of enclosure: (IP code) Rated voltage: Can be either line to line (``line voltage'') or phase Electrical machines can experience loss dissipation, which is... Show more

Rating and Loss Dissipation topics include: Losses and efficiency, machine ratings and loss dissipation.

An electrical machine's rating is the maximum capacity it can operate at. The rating plate lists the numerical values of electrical and mechanical quantities, including:
Power rating: Specified in apparent power (KVA or MVA)
Power factor (PF): The nominal power factor for other ratings
Insulation class: For the primary coil
Type of enclosure: (IP code)
Rated voltage: Can be either line to line (``line voltage'') or phase

Electrical machines can experience loss dissipation, which is when part of the input electricity is converted into heat. Power dissipation is a measure of how much power in a circuit is converted into heat. It's a naturally occurring process that occurs in all resistors that are part of a circuit and have a voltage drop across them. 

Here are some other loss mechanisms in electric motors: Mechanical loss, Resistive loss, Magnetic losses. 

Here are some examples of unwanted effects that can cause loss in electrical systems:
Unwanted heating of resistive components
The effect of parasitic elements (resistance, capacitance, ...) 

Tools for calculating losses can be found in two classes:
Those that rely on device models: SPICE is a typical example
Those that rely on mathematical models generated from test results: More sophisticated tools can calculate junction temperature in a specific application 
 

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