In case of D.C. machines, mechanical losses are primary function of

The correct answer is: C. Speed

Mechanical losses in a DC machine are the losses that occur due to the friction and windage of the rotating parts. These losses are proportional to the square of the speed of the machine.

• Current does not affect mechanical losses directly. However, current can affect mechanical losses indirectly by causing heating of the machine’s windings. This heating can cause the windings to expand, which can increase friction and windage losses.
• Voltage does not affect mechanical losses directly. However, voltage can affect mechanical losses indirectly by causing the machine to draw more current. This increased current can cause the machine to heat up, which can increase friction and windage losses.
• None of the above is not the correct answer. Mechanical losses are a function of speed, not current, voltage, or any other factor.