Table of Contents
What is constant load torque?
A constant torque load implies that the torque required to keep the load running is the same at all speeds. A good example is a drum-type hoist, where the torque required varies with the load on the hook, but not with the speed of hoisting. An example is shown in Fig. 11.7.
What is a constant torque VFD?
Constant torque is achieved because the VFD is increasing the voltage to the motor as it increases the speed. This relationship keeps the current and torque to the motor relatively constant. Typical applications are: Traction Drives, Compressors, Conveyors, Mixers, and Hoists.
What is torque load?
Load torque is the amount of torque constantly required for application and includes friction load and gravitational load. The faster the load needs to accelerate, the higher the acceleration torque is. Sometimes the load torque is higher; sometimes the acceleration torque could be higher.
What is the difference between constant torque and variable speed?
With constant torque loads, the torque loading is not a function of speed. As the speed changes, the load torque remains constant and the horsepower changes linearly with speed. Constant torque loads cause motors to draw relatively high current at low speeds when compared to variable torque applications.
Are blowers constant torque?
Constant torque applications include machines such as: extruders, compressors, conveyors, positive displacement pumps and blowers and presses to name a few.
What is the relationship between torque and speed in constant torque loads?
3. What is the relationship between torque and speed in constant type loads? Explanation: Speed hoist is a perfect example of constant type loads in which torque variation is independent of speed. The speed-torque characteristics of this type of load are given by T=K where K is a constant.
Is a pump constant torque or variable torque?
Variable torque loads are loads that startup under no load. Typically these are fans and clean water (centrifugal) pumps. Constant torque loads are those that startup under a load. Typically these are positive displacement pumps, conveyors and general machining applications.
What is the relationship between torque and speed?
Torque is inversely proportional to speed. Thus, when speed increases, torque will decrease.
What is the relationship between torque and speed Mcq?
The relation between torque and speed are inversely proportional to each other. The torque of a rotating object can be mathematically written as the ratio of power and angular velocity.
Why does a shunting motor draw more current?
Despite the load changes, Shunt motors can maintain their constant speed. As the load increases the armature slows down its speed. This results in less back electromagnetic force. This less back EMF accounts for less opposition against the supplied voltage. So, the motor will draw more current.
What is the torque loading of a motor?
For constant horsepower loads, the torque loading is a function of speed up to 100\% operating speed. As the speed of the operation is decreased, the torque increases so that the horsepower required remains essentially constant.
What is DCDC shunt motor?
DC shunt motor is a constant speed motor. Even though it’s speed decerases a little with increase in load. In order to meet the increasing load demand the torque of the motor should increase and we know that torque is inversly proportional to speed so the speed decerases.
Why is the flux constant in a shunt motor?
In a shunt motor, flux is constant because the field current is constant because of high resistance along field winding. Speed is directly proportional to Eb and inversely proportional to flux which is constant in the shunt. Eb decreases slightly because of increase in Ia due to loading.