## What are the types of DC motor Mcq?

DC Motors MCQ Question 7

There are mainly 3 types of DC motor starters, such as 2 point starter, 3 point starter and 4 point starter.

**What is the working principle of DC motor Mcq?**

DC Motor Principle MCQ Question 1 Detailed Solution

The commutator on the DC generator converts the AC into pulsating DC. In the case of a DC generator, the induced EMF is AC in nature. To convert the AC-induced EMF into the required DC, a commutator is required.

**When DC supply is given to the armature of a DC machine it produces Mcq?**

Iron and friction lossses amount to 1000W. Armature resistance 0.2Ω, series field resistance 0.2Ω.

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Q. | When a dc machine is connected to the dc supply main it will produce: |
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B. | emf in phase with the applied voltage |

C. | emf decreases with time |

D. | none of the above |

Answer» a. emf in opposition to the applied voltage |

### What will happen if DC shunt motor is connected across AC supply?

If a DC series motor is connected to a ac supply same current will flow through the series field and armature field after being rectified by the commutator. So, the machine will run but with high sparking at brush, poor pf, low speed and low efficiency.

**What is the unit of back emf?**

Since the back electromotive force is proportional to the moving speed, it is a constant. The unit is [V/m/s].

**What is the function of DC motor?**

A Direct Current (DC) motor is a motor that turns energy from a direct current and turns this into mechanical energy. The first DC motor was developed around the 1830’s-1840s. They were commercially unsuccessful, because these motors were battry powered and batteries were still very expensive and the quality was low.

#### Where is DC motor used?

Owing to the fairly constant speed and medium starting torque of shunt DC motors, they are used in the following applications: Centrifugal and reciprocating pumps. Lathe machines. Blowers and Fans.

**Why is DC motor used?**

Many applications require a high starting torque. The D.C. motor, by its very nature, has a high torque vs. speed characteristic, enabling it to deal with high resistive torques and absorb sudden rises in load effortlessly; the motor speed adapts to the load.

**Why starter is used in DC motor?**

Starters are used to protect DC motors from damage that can be caused by very high current and torque during startup. They do this by providing external resistance to the motor, which is connected in series to the motor’s armature winding and restricts the current to an acceptable level.

## Can a DC motor run on AC?

We already know that in a DC Series motor the field winding has very less resistance than a DC Shunt Motor as the field is connected in series with the Armature Winding. So if we give AC supply on a DC Series Motor it will run perfectly. In fact, DC Series can run on both AC and DC supply.

**Can a DC motor be converted to AC?**

Typically, converting from DC technology to AC will save your process 20-30% in energy consumption. The conversion not only changes the active motors to AC but also the controlling variable speed drives.

**Which supply is given to DC motor?**

The brushed DC electric motor generates torque directly from DC power supplied to the motor by using internal commutation, stationary magnets (permanent or electromagnets), and rotating electromagnets.

### What is armature current?

In electrical engineering, the armature is the winding (or set of windings) of an electric machine which carries alternating current.

**What is torque constant?**

The Torque Constant defines the torque-current relationship of a motor and is in Nm/amp. The motor and torque constants are related by the formula Km = Kt(trap)/sqrt(R), where R is the phase-to-phase resistance of the winding.

**Where is DC current used?**

Direct current is used in any electronic device with a battery for a power source. It is also used to charge batteries, so rechargeable devices like laptops and cell phones come with an AC adapter that converts alternating current to direct current.

#### What is the principle of DC machine?

The working principle of a DC machine is when electric current flows through a coil within a magnetic field, and then the magnetic force generates a torque that rotates the dc motor.

**What is DC motor principle?**

The DC motor is the motor 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 a 2 point starter?**

In case of series motors, field and armature are inserted and hence starting resistance is inserted in series with the field and armature. Such a starter used to limit the star4ting current in case of dc series motor is called two point starters.

## What is a 3 point starter?

A three-point starter is an electrical device, used for starting as well as maintaining the DC shunt motor speed. The connection of resistance in this circuit is in series which decreases the initial high current and guards the equipment against any electrical failures.

**What is stator speed?**

(iii) Speed of stator magnetic field w.r.t. stator = N = 1500 rpm. Stator magnetic field is in the same direction. of rotation of rotor. (as N = N§) (iv) Speed of stator magnetic field w.r.t. rotor Magnetic field = zero Note: Both the stator field and rotor field rotate in the airgap at same synchronous speed.

**Can universal motor run on DC?**

Universal Motor is a special type of motor that can run on a DC supply or a single-phase AC supply. Since it can run both on AC and DC, it is called a universal motor.

### Do motors run on AC or DC?

A motor is a type of electrical machine that converts electrical energy into mechanical energy. These motor can either run on AC electrical energy or DC electrical energy. Therefore, the motors are classified into two main types; AC motor & DC motor.

**What is armature voltage?**

Armature voltage is the voltage developed at the terminals of the armature winding of an AC or a DC machine during generation of power. Formula to calculate DC motor armature voltage: Amature voltage in volts = V = k η Φ Where k is the constant based on armature design. η is armature speed in rpm.

**What is the rate of armature?**

Market Price of Armature is Rs 3,000/ Piece.

#### What is the SI unit of motor speed?

rad/s.

The SI Unit for speed is rad/s. However, most manufacturers use rpm as the unit to specify the rotational speed of the motors.