Most documentation and motor selection guides state that engineers should choose a safety factor of around 1.5 to 2.25. This refers to a multiplier for the amount of torque that the motor should supply and that the drive should be expected to output enough energy for.
How do you calculate factor of safety?
A very basic equation to calculate FoS is to divide the ultimate (or maximum) stress by the typical (or working) stress. A FoS of 1 means that a structure or component will fail exactly when it reaches the design load, and cannot support any additional load.
What is a safety factor in engineering?
In engineering, a factor of safety (FoS), also known as (and used interchangeably with) safety factor (SF), expresses how much stronger a system is than it needs to be for an intended load.
What is the service factor for an electric motor?
Motor service factor (SF) is the percentage multiplier that a motor can handle for short periods of time when operating within its normal voltage and frequency tolerance. In other words, it is a fudge factor that give extra horsepower when it’s occasionally needed. A SF is an operational margin.
What is the difference between service factor and safety factor?
Service factors are used to account for higher torque conditions of the equipment to which the coupling is connected. … Safety factors are used in the design of a coupling.
What is factor safety ratio?
: the ratio of the ultimate strength of a member or piece of material (as in an airplane) to the actual working stress or the maximum permissible stress when in use.
Can factor of safety be more than 1?
The factor of safety is the ratio of the allowable stress to the actual stress: … A factor of safety of less than 1 represents likely failure. A factor of safety of greater than 1 represents how much the stress is within the allowable limit.
What does a safety factor of 1.5 mean?
Factor of Safety. – FOS – For use with highly reliable materials where loading and environmental conditions are not severe and where weight is an important consideration. 1.3 – 1.5. For use with reliable materials where loading and environmental conditions are not severe.
What is a safety factor of 2?
Factor of safety (FoS) is ability of a system’s structural capacity to be viable beyond its expected or actual loads. … For example, a safety factor of 2 does not mean that a structure can carry twice as much load as it was designed for. The safety factor depends on the materials and use of an item.
What is the factor of safety Sanfoundry?
What is the factor of safety? Explanation: The ratio of ultimate stress to the permissible or working stress is called the factor of safety.
What is a good service factor?
The service factor – SF – is a measure of periodically overload capacity at which a motor can operate without damage. The NEMA (National Electrical Manufacturers Association) standard service factor for totally enclosed motors is 1.0.
What is motor duty?
Motor Duty / Load Cycle. The term duty defines the load cycle to which the machine is subjected, including, if applicable, starting, electric braking, no-load, and rest de-energized periods, and including their durations and sequence in time.
Is the most common cause of motor failure?
Low Resistance. The most common cause of motor failure, and arguably the most difficult to overcome, is low resistance. Low resistance is caused by the degradation of the insulation of the windings due to conditions such as overheating, corrosion, or physical damage.
What is the design factor?
The design factor is what the item is required to be able to withstand (second “use”). … By this definition, a structure with a FOS of exactly 1 will support only the design load and no more. Any additional load will cause the structure to fail. A structure with a FOS of 2 will fail at twice the design load.
Why factor of safety is used in design?
The Factor of Safety is essentially used to assure the structural designing does not occur any unexpected failure or presence of deformation or defect. The smaller the Factor of Safety, the higher chances was there for the design to be a failure. Resulting in an uneconomical and nonfunctional design.
What is over design factor?
Definition of Column Over-Design Factor
The mean values of the member strengths can be therefore used as the main factor in the investigation. For a one-storey one-bay structure, the COF is defined simply as the ratio between the mean value of the. column strength and the mean value of the beam strength.