The core losses are the hysteresis and eddy current losses. These losses are considered almost constant as the machines are usually operated at constant flux density and constant speed.
Which are constant losses?
Constant losses are those losses that always occur irrespective of the load conditions and whose value remains constant for a given machine. Mechanical losses, core losses, and shunt field copper losses are included in constant losses.
Why DC shunt motor is constant speed?
If the load on the motor increases armature speed reduces and thereby cause a reduction in the back emf. … Hence, a DC shunt motor always maintains a constant speed. Under no load condition, the back emf becomes nearly equal to the applied voltage.
Which of the following losses is not under constant losses?
8. Which of the following losses is not under constant losses? Explanation: All the losses that is friction and windage losses, no load core losses, shunt field core losses in shunt field and compound motors come under the category of constant losses, while iron losses come under category of variable losses.
What are the losses involved in a DC generator?
There are four internal losses that contribute to lower efficiency of a DC generator.
- Copper losses.
- Eddy-current losses.
- Hysteresis losses.
- Mechanical losses.
Which loss is a variable loss?
Copper losses:- when the transformer is loaded, current flows in primary and secondary winding, there is loss of electrical energy due to the resistance of the primary winding, and secondary winding and they are called variable losses.
What power is lost in the stator?
Motor power flow
Power is then lost in the stator circuit, and the stator core. The remaining power is transferred to the rotor. Deducting the rotor losses, one obtains the power converted to the mechanical system.
What is the principle of DC shunt motor?
Construction and Working Principle
The working principle of a DC Shunt Motor is, whenever a DC motor is turned ON, then DC flows throughout stator as well as the rotor. This current flow will generate two fields namely pole as well as the armature.
What is the main disadvantage of a shunt motor?
As the load changes, a shunt wound motor runs at a predictable speed. If variable speed is desired, constant speed can be a disadvantage. The lifetime of the motor is usually not improved by brushes.
Which motor is constant speed?
This motor combines a power on activated type clutch and brake with an induction motor. It is ideal for high-frequency starting and stopping. Suitable for applications where the motor is operated starting, stopping and reversing repeatedly and the motor is operated at synchronous speed regardless of load torque.
Which of the following is are variable losses?
Which of the following are variable losses? Armature copper loss is directly proportional to square of armature current. … Condition for maximum efficiency is, copper loss = iron loss or variable losses is equal to fixed losses.
What is the formula for total commutator loss for DC machine?
In the same way, brush values are also used in calculation of commutator loss. 13. What is the formula for calculation of brush current of DC machine for wave winding? Explanation: Brush Current = 2*(Armature Current) / P is the formula for the calculation of brush current of DC machine for lap winding.
Why shunt field losses are constant?
In a generator, the output voltage at the terminal should and must remain constant. To achieve this, the field produced by the shunt and series field must remain constant. … The resistance of series and shunt field is always constant once it is designed. And thus the copper losses are always constant.
Is a type of loss in a DC generator?
The losses that occur in a DC Machine is divided into five basic categories. The various losses are Electrical or Copper losses (I2R losses), Core losses or Iron losses, Brush losses, Mechanical losses, Stray load losses. These losses are explained below in detail.
How can generator losses be reduced?
How to Reduce Generator Loss in Operation
- The losses of diesel generators in operation can be divided into the following categories: …
- Running-in of diesel generator set. …
- The diesel generator set must be full of oil, water and air when working. …
- Clean oil, water, air and engine body is required. …
- Adjustment of associated technology of diesel generator sets.
What is eddy current loss?
Eddy current loss is conductive I2R loss produced by circulating currents induced in response to AC flux linkage, flowing against the internal resistance of the core.