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Why speed is decreased when field current increases in dc motor?
Wiki User
∙ 11y ago
Because with more field, the armature produces the same voltage at less speed. The voltage generated by the motor must always be less than the supply voltage. A motor that is driven faster than it wants to go becomes a generator.
Wiki User
∙ 11y ago
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When resistance decreases what happens to current?
Based on the simplest Electrical Equation V = I * R,(reads: voltage equals current multiplied by resistance)then, rearranged I = V / R .As resistance decreases, current flow proportionately increases
As a motor armature turns faster and faster net current in the motor windings decreases or increases or remains unchanged?
as a motor armature speed increases,the net current in the motor windings decreases due to MAGNETIC DRAG. which is a common phenomenon in the ac machines.
Why is motor current draw lower at full speed?
Because full speed is unloaded. As you load the motor, speed decreases, and slip increases, with an accompanying increase in current.
What field setting for a dc shunt motor wired in series on high voltage?
A shunt dc motor has quite different characteristics from a series motor. Wired in series, the same current passes through the armature and the field winding and it is most unlikely that a shunt motor would have a field winding that is suitable for this. Therefore a shunt motor cannot be wired as a series motor in general because its field winding is designed for only a small current.
What is difference between stab shunt dc motor and shunt dc motor?
A series motor respond by decreasing its speed with small increase in current for a given load torque. A shunt motor holds its speed nearly constant with large increase in input current for same amount of load torque
How speed increases when flux decreases in dc shunt motor?
Increasing flux, torque of the dc motor will be increased and speed of the dc motor will be decreased as speed of the dc motor is inversely proportional to that of the flux and the torque of the dc motor is directly proportional to the flux.
What is the effect of field current on dc motor?
The field current of a dc motor provides the magnetic field that allows the motor to develop a torque when current flows through the armature..
When resistance decreases what happens to current?
Based on the simplest Electrical Equation V = I * R,(reads: voltage equals current multiplied by resistance)then, rearranged I = V / R .As resistance decreases, current flow proportionately increases
In synchronous motor theory is excitation current the same as field current?
yes. excitation current is same as field current to my knowledge
What causes speed drop in motor?
1) If current, at 'on load' condition, reach or cross its rated value, then the speed of the motor will be decreased. 2) If there is any voltage droop occurs in the incoming supply then the speed of the motor will be decreased.
As a motor armature turns faster and faster net current in the motor windings decreases or increases or remains unchanged?
as a motor armature speed increases,the net current in the motor windings decreases due to MAGNETIC DRAG. which is a common phenomenon in the ac machines.
What is the difference between field current and voltage?
Field Current in a DC Motor is the flow of electrons through the field circuit by a field controller. The flux of the motor, that with the armature current generates torque, is directly proportional to the field current. Field Voltage is the electrical potential energy applied on the field circuit by a field controller. Legacy Field Controllers controlled the field voltage. Using I=V/Z (Z=R+iX) the field current is then indirectly controlled. Due to the heat generated by E=i2 R t in the motor, the resistance R would decrease, increasing the field current and therefore changing the base speed of the motor and disturbing the control. Newer field controllers control the field current eliminating this problem
Would it be correct to say with a fixed field voltagethe speed of a shunt motor is proportional to its armature voltage?
With increasing torque load the armature tends to slow down; the motor draws more current to compensate, and if there is armature resistance the back emf generated by the armature falls to allow the increased current to flow, which causes the motor to settle at a lower speed. The mechanical output power is the speed times the torque, and increasing the torque increases the power output provided the speed does not drop much.
Why is motor current draw lower at full speed?
Because full speed is unloaded. As you load the motor, speed decreases, and slip increases, with an accompanying increase in current.
How field current change in 'V and inverted v curves ' of synchronous motor?
In v curves armature current decreases in under excitation and increase in overexcitation as fielcurrent increases and armature current is maximum at unity power factor.The power is maximum when load angle is equal to impedance angle.A linear motor is a essentially a multi phase
What role does the armature do in a DC motor?
One of the role of the armature in the DC motor is to carry the current that is crossing the field. By carrying the current crossing the field, it creates the shaft torque in the rotating machine.
How does a high frequency induction motor work?
In a high frequency induction motor, EMF is induced leading to current flow. Torque in the rotor coil increases. As frequency increases, Impedance of the Rotor increases and currency reduces.
