![possibl values of synchronous speed ns possibl values of synchronous speed ns](https://teamwork.gigaset.com/gigawiki/download/attachments/1133215968/image2020-8-18_15-27-36.png)
It is limited by the motor's rated torque, temperature rise and the strength of the gearhead combined with the motor. The permissible torque is the maximum torque that can be used when the motor is running. Static friction torque is the torque output required to hold a load when the motor is stopped by an electromagnetic brake or similar device. This is the torque generated when the motor is continuously producing rated output power at the rated voltage and frequency. If a load greater than this torque is applied to the motor, it will stall. This is the maximum torque under which the motor will operate at a given voltage and frequency. If the motor is subjected to a friction load greater than this torque, it will not operate.
![possibl values of synchronous speed ns possibl values of synchronous speed ns](https://www.pumpsandsystems.com/sites/default/files/impact3.jpg)
This is the torque generated instantly when the motor starts. The following formula is one method of expressing speed: From the standpoint of utility, it is the most desirable speed. This is the appropriate speed of the motor at rated output power. The speed of induction or reversible motors under no load conditions is lower than synchronous speed by a few percent (approximately 20 to 60 r/min). This is the speed under no load conditions. This is an intrinsic factor determined by line frequency and the number of poles.įor example, for a four-pole motor with a line frequency of 60 Hz, the synchronous speed will be: When operation at rated output is possible only for a limited time, it is known as the limited duty rating. When continuous operation at rated output is possible, it is known as a continuous rating. The time during which output can continue without abnormality is called a time rating. These are known as rated output power, rated voltage, rated frequency and rated speed, respectively. Operation limit on output power, as well as voltage, frequency and speed are established. There are two categories: continuous rating and limited duty rating. Motor rating represents the operation limit certified on the motor regarding dynamic characteristics such as temperature, mechanical strength, vibration and efficiency. It is normally indicated either by angle or by rotations. This is the number of excess rotations the motor makes from the instant the power is cut off to the time that it actually stops. Generally, the term "output power" refers to rated output power. The speed and torque that produce the rated output power are called the rated speed and rated torque. This term refers to output power generated continuously when the optimal characteristics are achieved at the rated voltage and frequency in continuous operation.
![possibl values of synchronous speed ns possibl values of synchronous speed ns](https://image.slidesharecdn.com/samplescripts-160921073416/95/matlab-scripts-examples-11-638.jpg)
Output power is expressed in watts or in horsepower. Each motor specification indicates the value of rated output power. The amount of work that can be performed in a given period of time is determined by the motor's speed and torque. The maximum thrust load on the gearhead is called the permissible thrust load, which varies with the gearhead type. This is the load that is placed in the direction of the gearhead output shaft. This is equivalent to tension under belt drive. The maximum overhung load on a gearhead shaft is called the permissible overhung load, and it varies with the gearhead type and distance from the shaft end. This is a load on the gearhead output shaft in the vertical direction. As the gear ratio increases, the number of reduction gear stages increases, with a consequent reduction in the gear efficiency to 73% and 66% for each gear stage added. Transmission efficiency is, when using a GN gearhead, usually 90% for one stage of reduction gears, and is 81% for two stage gearheads. It is expressed as a percentage (%) and is determined by the friction in the gears and bearings used in the gearhead and the resistance of the lubrication grease. This is the efficiency when the torque is transmitted with the gearhead combined. These values are determined in accordance with the results of life tests under various loads and conditions of use. This is a coefficient used to estimate the gearhead life. Therefore, it varies according to the gearhead type and gear ratio. It is dependent upon such mechanical strength factors as the materials of gearheads and bearings, and size. This is the maximum load torque that can be applied to the gearhead. The speed at the gearhead's output shaft is 1 Gear Ratio times the motor speed. The gear ratio is the ratio by which the gearhead reduces the motor speed.