1 Answer. In a dc shunt motor, the field resistance is generally very high. This is to avoid high current through field. … So, as line current = armature current + field current, and field current is negligible compared to armature current, we can approximate line current to armature current.

## What is line current in a motor?

What is line current: The measure of current in one phase before the star or delta arrangement of the component is called line current (typically input current in motor or output current in the alternator). In three phase balanced system, it may be R phase current or Y phase current or B phase current.

## What is field current in dc motor?

: the current supplied to the field windings of a generator or motor to establish the magnetic field for its operation.

## What is line current in generator?

The current flowing in the line ( outside the transformer) is called line current whereas current flowing in one of the windings of the transformer or generator is called phase current.

## How do you calculate current in a DC motor?

Calculate the field current for the motor using the formula I = V/R where I is the field current. As an example, assume V is 40 volts and R is 500 ohms: I = 40/500 = 0.08 amps.

## Is line current the same as armature current?

Field currents may be derived from the line also, but the current is much smaller so that to a first approximation, the armature current and the line current are the same.

## What is the definition of line current?

Line current is the current through any one line between a three-phase source and load. … In balanced “Y” circuits, the line voltage is equal to phase voltage times the square root of 3, while the line current is equal to phase current.

## What is DC motor working principle?

The DC motor is the device which converts the direct current into the mechanical work. It works on the principle of Lorentz Law, which states that “the current-carrying conductor placed in a magnetic and electric field experience a force”.

## What is flux in DC motor?

When both the armature and the field windings are excited by a DC supply, current flows through the windings and a magnetic flux proportional to the current is produced. When the flux from the field interacts with the flux from the armature, it results in motion of the rotor.

## What is DC motor with diagram?

Difference Between Dynamo and DC Motor – definition

Sr No. | Dynamo | DC Motor |
---|---|---|

2. | Here normally permanent magnet is used or electromagnets made up of windings | Made of miniature size of permanent magnet |

3. | It can operate through Self Excitation or Separate Excitation | It is usually excited by permanent magnet present. |

## How many volts is a 3 phase line?

3 phase system is expressed with line voltages. The line votage is 440 volt. Also the voltage between any one phase and neutral for a 3 phase system is 240 volts.

## What is the symbol for 3 phase?

A three-phase system may be arranged in delta (∆) or star (Y) (also denoted as wye in some areas).

## What is the efficiency of dc motor?

The value of the efficiency of a DC motor could typically be in the range of 70 to 85%. Larger the machine higher will be the efficiency. Losses consist of Armature and field copper losses, core loss, friction and windage loss.

## How many amps does a DC motor draw?

Full load amps in 120 and 240 volts DC motors

Motor Rating (hp) | Current (amps) | |
---|---|---|

120 V | 240 V | |

1 | 9.5 | 4.7 |

1 1/2 | 13.2 | 6.6 |

2 | 17 | 8.5 |

## How do you calculate the RPM of a 12v DC motor?

One crucial measurement is revolutions per minute, or RPM, which describes the speed of a motor.

…

Motor RPM Calculation Examples

- (Hz x 60 x 2) / number of poles = no-load RPM.
- (60 x 60 x 2) / 4.
- 7,200 / 4 = 1,800 RPM.