Which of the following motor used in elevator?
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 usually employed for trolley bus?
Mostly DC series motors are used in this system. For trolley buses and tramways, DC compound motors are used where regenerative braking is required. The various operating voltages of DC traction system include 600V, 750 V, 1500V and 3000V.
Why dc motor is used in traction?
DC series motor has develops high torque at low speeds, low torque at high speed, this is the basic requirement of traction unit. Commutating property of series motor is good so we get sparkles commutation. Torque is unaffected by variation in supply voltage. DC Series motor maintenance cost is less.
Why dc shunt motor is not suitable for traction?
DC shunt motors are not suitable for traction purpose, the reasons are given below: 1. The dc shunt motor is a constant speed motor and its speed-torque characteristic does not meet with the requirements of traction. i.e., the power drawn from supply mains varies directly as the load torque.
What are the types of DC motor?
There are 4 main types of DC motors:
- Permanent Magnet DC Motors. The permanent magnet motor uses a permanent magnet to create field flux. …
- Series DC Motors. In a series DC motor, the field is wound with a few turns of a large wire carrying the full armature current. …
- Shunt DC Motors. …
- Compound DC Motors.
Which DC motor is preferred for constant speed?
Which D.C motor is preferred for machine tools? Explanation: DC shunt motor is a constant speed motor tool machine such as lathe machine requires being run at a constant speed. As lathe machines roll down iron pieces reducing Diameters at a constant speed.
Are locomotives AC or DC?
Rectifier locomotives, which used AC power transmission and DC motors, were common, though DC commutators had problems both in starting and at low velocities. Today’s advanced electric locomotives use brushless three-phase AC induction motors.
Which motor is used in bus?
The bus uses a multi- motor system in which each mechanism is driven by one motor. The BLDC 200 KW 380V is used as prime mover. Maximum torque that can be achieved around 700 Nm. Motor works on a voltage between 230 ~ 400 VDC.
What kind of motors are in a bus?
In city transport, series-wound DC motors were used . . . . now the choice of brushless DC motors and 3-phase AC induction motors. These motors have excellent starting torque. Articulated trolleybuses typically are powered by electric motors that develop over 200-Hp.
Which motor is used in traction?
Explanation: DC motors are used for traction as, according to the characteristics of DC motors speed is inversely proportional to torque and square of armature current as well, if linear magnetization is concerned. Thus, DC motors are perfectly suitable for traction.
Which current is used in railways?
Railway electrification systems using alternating current (AC) at 25 kilovolts (kV) are used worldwide, especially for high-speed rail.
Which DC motor is used in shears and 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.
What is V F control method?
V/F is abbreviated from voltage/frequency. V/F control is an induction motor control method which ensures the output voltage proportional with the frequency, so it maintains a constant motor flux, preventing weak magnetic and magnetic saturation phenomenon from happening.
What is Crest speed?
Crest speed. It is the maximum speed of train, which affects the schedule speed as for fixed acceleration, retardation, and constant distance between the stops. If the crest speed increases, the actual running time of train decreases.
What controls the speed of a DC motor?
Thus, the speed of a DC motor can control in three ways: By varying the flux, and by varying the current through field winding. By varying the armature voltage, and the armature resistance. Through the supply voltage.