Which DC motor is used in shears and punches? Explanation: Cumulative compound DC motor provides high starting torque which is required at instant of starting in shears and punches. It also provides good speed regulation in order to vary pressure.
Which motor is most suitable for punch presses?
The type of D.C. motor used for shears and punches is
- A. Shunt motor.
- Series motor.
- Differential computed D.C. motor.
- Cumulative compound D.C. motor.
Which DC motor is used for machine tools?
1. For machine tools, which DC motor can be used? Explanation: Shunt characteristics is the speciality of DC shunt motor. The speed of the motor almost remains constant on various loads, thus it suits perfectly to the application, where speed requirement is constant like in machine tools.
Which DC motor is used for rolling mills?
1. DC Series Motor. Since it has high starting torque and variable speed, it is used for heavy duty applications such as electric locomotives, steel rolling mills, hoists, lifts and cranes.
Which DC motor is more preferred for elevators?
DC cumulative compound motor having high starting torque up to 450% depending upon the degree of compounding. The speed regulation is varying up to 25 ~ 30%. That’s why these motors are used in elevators.
Which motor is used in punches?
Which DC motor is used in shears and punches? Explanation: Cumulative compound DC motor provides high starting torque which is required at instant of starting in shears and punches. It also provides good speed regulation in order to vary pressure. So, this motor suits well to shears and punches application.
What will happen if DC motor is used without starter?
What will happen if DC motor is used without starter? Explanation: It would cause intolerably heavy sparking at the brushes which may destroy the commutator and brush-gear. Sudden development of large torque will cause mechanical shock to the shaft, reducing its life.
What is starting resistance of DC motor?
In practical DC machines, armature resistance is basically very low, generally about 0.5 Ω. Therefore, a large current flows through the armature during starting.
What is a DC series motor?
Series DC motors are a group of self-excited DC motors in which the field coil is connected in series to the armature winding and thus a higher current passes through it. A series DC motor mission is to turn the electrical energy into mechanical one based on electromagnetic law.
Which motor is preferred in elevators?
Lifts are preferred by AC slip ring or DC compound motor. In case of single phase installation, the commutator motors are preferred. Variable Frequency drive electronic controls are used in the latest lift designs.
What is back emf in dc motor?
When armature of dc motor rotates, the armature conductors move through the magnetic field, emf is induced in them. The induced emf acts in opposite direction to applied voltage. This voltage is known as back emf.
When the speed of dc motor is increased?
From the equation. (3) we can say, speed is inversely proportional to armature current. Thus, when the speed of the dc motor is increased, the armature current will decrease.