MULTI QUADRANT OPERATION OR FOUR QUADRANT OPERATION


What is Multi quadrant Operation:

    Multi quadrant operation performs in all four quadrants. The main thing is the important of convention about the speed and torque operation in these quadrants. A motor performs in two different modes, one is Motoring mode and another one is Braking mode.

In motoring mode, The electrical energy is converted into mechanical energy, which supports all its motion. 

In braking mode, The mechanical energy is converted into electrical energy and it works as a generator type and thus restricts the motion. 

Motor can perform both forward and reverse directions. For motoring mode, it performs positive power development and for braking, it performs negative power development.


Multi quadrant


       Forward Motoring is otherwise known as first quadrant operation, Here the power developed is positive and the machine words as supplying mechanical energy from the motor. The second quadrant is said to be forward braking because the power developed is negative and the machines works to oppose the motion through braking. Likewise the third and forth quadrants as determined as reverse motoring and reverse braking.

Here we see the example for better understanding, So let us consider the operation of the hoist in multi quadrant or four quadrants shown below.

hoist in four quadrants


From the above diagram, We obtain that the direction of motor and load torque and the speed of direction are be shown by arrow symbols. A hoist is a device that moves people or objects from one level to another by winding a rope around a drum that is connected to the motor shaft at one end. A counterweight is attached to the rope's other end. The counterweight's weight is set to be higher than that of an empty cage but lower than that of a cage that is completely loaded. The cage will move upward when the motor speed is directed forward. The speed-torque characteristics of the loaded hoist are represented by the load torque line in quadrants I and IV. This torque represents the variance in torques caused by the counterweight and a loaded hoist.

The speed torque characteristics for an empty hoist are represented by the load torque in quadrants II and III. This torque is the difference between the torques caused by the counterweight and the empty hoist. Because the counter weight is always more than that of an empty cage, its sigh is negative.
A hoist's quadrant I functioning necessitates cage upward movement, which correlates to positive motor speed in the counterclockwise direction here. This motion will occur if the motor produces a positive torque in the CCW direction equal to the magnitude of the load torque TL1. This is a forward driving activity since the created power is positive.

When a loaded cage is lowered, it enters Quadrant IV. Because the weight of the loaded cage is greater than the weight of the counterweight. It is able to overcome gravity on its own. To keep the cage within a safe range, the motor must generate a positive torque T equal to TL2 in the anticlockwise direction. Because both power and speed are negative, the drive is in reverse braking mode. When an empty cage is shifted up, operation in quadrant II is gained. Because a counterweight is heavier than an empty cage, it may pull it up. To keep the speed within a safe range, the engine must deliver a braking torque equal to TL2 in the clockwise direction. Because speed is (+) and power development is (-), so it is forward braking operation.

The operation in quadrant III is accomplished by lowering an empty cage. Due to the fact that an empty cage weighs less than a counterweight, the motor should generate torque in the CW direction. This is reverse motoring action since speed is negative and produced power is positive.