To ensure that the Lathe machine's motor working properly, DC motor starter is added in which it used to protect motor against damage from: • short-circuit, • long term overload, • excessive starting current, and yet to made the operating speed of motor easily to be control by operator. During starting, the motor is not turning, hence there is no internal voltage .The internal resistance is very low and thus the current flow through is very high. This condition may cause damage to the motor Hence, a staring resistor is added in which connect in series with the armature to limit the current flow until the internal voltage of motor is increasing to do the limiting. In order to prevent losses as the speed of the motor is build up; the starting resistor should be removed
A DC shunt motor usually runs on a fixed-voltage supply.
1. The field current sets the field intensity, and the armature voltage is proportional to the field intensity and the armature speed.
2. The armature current is the difference between the supply voltage and the armature voltage, divided by the armature resistance.
3. The torque is proportional to the field intensity and the armature current.
That's about all you need to know.
In an ideal motor the armature has zero resistance and the armature rotates at a constant speed determined by the supply voltage and the field current (from 1.). If the field current is increased, the speed falls.
The armature current is determined by the load torque (from 3.).
In a non-ideal motor there is a finite armature resistance, an increased load torque causes more current to be drawn, and the armature voltage has to fall so that the current can flow, so the speed falls.
Some Uses of DC Shunt motors are as below:
Reciprocating pump
Centrifugal pump
Lathe
Blower and Fan
Machine tools
Constant speed line shaft, etc...
D.C. motors are categorised according to the way in which the field winding is connected in relation to the armature winding. The term 'shunt' is an archaic word for 'parallel', so a d.c. 'shunt motor' is one in which the field winding is connected in parallel with its armature winding. Another category is the d.c. 'series motor', in which the field winding is connected in series with the armature winding. Yet another category is the d.c. 'compound motor', in which there are two field windings; one in parallel, and the other in series, with the armature winding. Each of these connections gives a d.c. motor a different operating characteristic, making them suitable for different types of load.
'Shunt' is an archaic term for 'parallel'. So a 'shunt d.c. motor' is one whose field winding is connected in parallel with the supply voltage.
Dc shunt implies field windings in parallel to armature,dc series means field windings in series with armature windings.
swinburne's test on dc shunt machine is to predetermine the efficiency of the dc machine , but it is not accurate it is just like estimation of efficiency of dc shunt machine when it is run as a motor and a generator............................
Dc shunt motor is a constant flux and constant speed motor . So that it is used in centrifugal pumps ,machine tools ,blowers and fans etc.
Dc shunt motor is constant speed motor.Its speed is constant with armature current.This shunt motor is used in paper mills and drilling machines
on adding load on a dc shunt motor, the amount of current and torque will increase. but terminal voltage will decrease
dc shunt motors
A DC shunt motor is a motor using DC supply with the the inductor connected parallel to the armature.
A shunt DC motor connects the armature and field windings in parallel or shunt with a common D.C. power source. This type of motor has good speed regulation even as the load varies, but does not have the starting torque of a series DC motor
Dc shunt motor is constant speed motor.Its speed is constant with armature current.This shunt motor is used in paper mills and drilling machines
swinburne's test on dc shunt machine is to predetermine the efficiency of the dc machine , but it is not accurate it is just like estimation of efficiency of dc shunt machine when it is run as a motor and a generator............................
DC Shunt motor
applications of series motor
applications of series motor
Dc shunt motor is a constant flux and constant speed motor . So that it is used in centrifugal pumps ,machine tools ,blowers and fans etc.
It will drawn a large amount of current which can destroy the shunt
A DC shunt motor is a motor using DC supply with the the inductor connected parallel to the armature.
Dc shunt motor is constant speed motor.Its speed is constant with armature current.This shunt motor is used in paper mills and drilling machines
DC shunt motor can be reversed by changing the polarity of either the armature coil or the field coil.