For motor, Eb = Vt − IaRa Mechanical power developed by the motor is given by Pm = EbIa ⇒ VtIa − Ia2Ra. Mechanical power developed by the motor will be maximum if dPm/dIa is zero.

## What is the mechanical power developed by a dc series motor is maximum?

What is the mechanical power developed by a DC series motor is maximum? Back emf is equal to half the applied voltage. Back emf is equal to applied voltage. Back emf is equal to zero.

## What makes a motor stronger?

Strength of a motor:

The strength of the motor (torque) is determined by voltage and the length of the wire in an electromagnet in the stator, the longer the wire (which means more coils in the stator) the stronger the magnetic field. This means more power to turn the rotor.

## Why is field winding of a dc series motor provided with thick wire?

Explanation: In DC series motor, the cross-sectional area of wire used for field coils has to be large because the in this case field coils carry the load or armature current. As the cross-sectional area is large, the resistance is minimum and series voltage drop is also minimum.

## Which type of motor has high starting torque?

DC motor

## When the speed of DC motor is increased?

The speed of a dc motor is changed by changing the current in the field or by changing the current in the armature. When the field current is decreased, the field flux is reduced, and the counter emf decreases. This permits more armature current. Therefore, the motor speeds up.

## What are 4 ways to decrease the strength of an electric motor?

The four main factors that affect the strength of an electromagnet are the loop count, the current, the wire size, and the presence of an iron core.

## What is the most efficient motor?

Tests carried out on a 44 megawatt 6-pole synchronous ABB motor shortly before delivery showed an efficiency 0.25 percent greater than the 98.8 percent stipulated in the contract, resulting in the world record for electric motor efficiency.

## How can we increase motor power?

Here are some ways in which you can improve the performance of your electric motors:

- Eliminate Voltage Unbalance. …
- Eliminate Voltage Unbalance. …
- Connect Motors to Variable Frequency Drives (VFDs) to Improve Efficiency. …
- Connect Motors to Variable Frequency Drives (VFDs) to Improve Efficiency. …
- Choose Motors in the Right Size.

## Which motor has the poorest speed control?

DC motor

## Why is the DC motor preferred over AC motor?

DC motors have the advantage of: higher starting torque, quick starting and stopping, reversing, variable speeds with voltage input and they are easier and cheaper to control than AC. AC motor advantages include: lower power demand on start and minimal maintenance.

## Which motor Cannot be started on no load?

This is the reason why series motor should never be started on light loads or no load conditions. In any DC motor the speed depends inversely on the flux and directly proportional to emf, N ~E/flux. At no load the armature current is very less and so is the flux, since the series winding has less number of turns.

## What is a starting torque?

Starting torque is the torque transferred by the shaft coupling during run-up (see Start-up process). It is calculated based on the ratio of power (P) to angular velocity (ω) and is represented as a rotational speed function.

## What type of single phase motor has the highest starting torque?

The capacitor-start motor develops a much higher starting torque, i.e. 3.0 to 4.5 times the full-load torque.To obtain a high starting torque, the value of the starting capacitor must be large, and the resistance of starting winding must be low.

## Which motor has high starting current?

Induction Motor