Torque breakdown

Locked-rotor torque.% Breakdown torque...% or for general-... 

Pull-out or breakdown torque (maximum torque) Rated torque... 

The spced-torqtie characteristic is the lehitionship between the torque and the speed, in the range from zero to synchronous speed. This relationship, when expressed as a eui ve. w ill include breakdown torque (pull-out torque), pull-up toi que and starting torque. The speed-current characteristic is the relationship of the current to (he speed. 

Pull-up torque For an alternating current motor, this is the minimum external torque developed hy the motor during the period of acceleration from rest to the speed at which breakdown torque occurs. For motors that do not have a definite breakdown torque, the pull-up torque is the minimum torque developed up to the rated speed. 

Breakdown torque For an alternating current motor, this is the maximum torque that it will develop with rated voltage applied at rated frequency, without an abrupt drop in speed. 

The pull-out or breakdown torque must be greater than the maximum torque required by the driven equipment to prevent stalling, usually 150% of full load torque for unity-power fector motors and 220-225% for 0.8 leading power factor motors. ... 

The heat run will he equivalent load method. Efficiency at full, and V2 load and power factor at full, /4 and V2 load and breakdown torque will be determined by equivalent circuit calculation (IEEE 112,... 

Design L. A Design L motor is a single-phase integral-horsepower motor designed to withstand full-voltage starting and to develop a breakdown torque as shown in MG 1-10.33 with a locked-rotor current not to exceed the values shown in MG 1-12.33. 

Design A produces exceptionally high breakdown torques but at the expense of high locket rotor currents that normally require provision for starting with reduced voltage. This motor is suitable for machines in which the friction and inertia loads are small. 

Table 3-7 gives the typical breakdown torque for Design B and C motors with continuous ratings [8]. Breakdown torques for Design A motors are in excess of the values given for Design B motors. 

Breakdown Torque of Design B and C, 60 and 50-cycle Motors with Continuous Ratings [8]... 

BREAKDOWN TORQUE PERCENT LOCKED ROTOR AMPERES ... 

In order to select the most economical drive for an Injection molding machine, the duty cycle must be calculated (3). This calculation must be made for each specific application to determine the applicable motor rating. A typical duty cycle Is shown In Figure 3. The motor rating Is defined In terms of 1) Nameplate horsepower and service factor (SF) and 2) Breakdown torque In terms of full load. One first calculates the RMS HP via Equation (1). ... 

Torque requirements must also be considered. The motor must be capable of carrying the peak horsepower (torque) value from the duty cycle at 90 percent voltage. Motor breakdown torque Is reduced by the square of the voltage. The relationship Is given In Equation (5). 

Some process equipment such as reciprocating pumps, compressors, and conveyors must be started while fully loaded other drives such as centrifugal pumps, fans, and agitators have light loads at starting. Many applications require considerably more torque to start and accelerate the load than to run it the reverse is also true. Starting torque, maximum or breakdown torque, inertia of the load, and the accelerating time must be considered. 

In practice Ri is much smaller than Xn and so the maximum torque is very dependent upon the value of the leakage reactances, especially the rotor leakage reactance X2. The maximum torque is also called the breakdown torque. 

For any joint or joint complex, muscle performance can be quantified in terms of the basic dimensions of performance strength, speed, endurance, steadiness, and coordination. Muscle strength is the capacity to produce torque or work by voluntary activation of the muscles, whereas muscle endurance is the ability to maintain a predetermined level of motor output — for example, torque, velocity, range of motion, work, or energy — over a period of time. Fatigue is considered to be a process under which the capability of muscles diminish. However, neuromuscular adjustments take place to meet the task demands (i.e., increase in neural excitation) until there is final performance breakdown — endurance time. Coordination, in this context, is the temporal and spatial organizations of movement and the recruitment patterns of the muscle synergies. 

C. If the above protective measures fail, the high torque produced by the motor will cause a slow breakdown of the bearings and not a rapid shaft seizure. Industry experience indicates that the babbitt bearing surfaces wear away and the bearing pads and sleeves will be badly worn but the shaft will continue to rotate. 

F Double-cage, low-torque Uneconomical for most industrial loads because of their high starting-torque to breakdown-torque ratio. 

Pull-up torque The minimum torque developed by the motor during the period of acceleration from zero speed (rest) to the speed at which breakdown occurs. 

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