What do u mean by factor of safety?
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 factor of safety in civil engineering?
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 a safety factor of 5?
These slings are designed with a safety factor of 5:1. This means that 5 times as much force as the working load limit has to be applied to the sling before it potentially fails. This means the wire rope slings have a Breaking Strength of up to 180,000 lbs and the round synthetic slings can withhold up to 700,000 lbs.
How is SWL calculated?
To calculate the SWL in kilograms of FSWR square the rope diameter (D) in millimetres (mm) and multiply by 8.
- Formula: SWL (kg) = D2(mm) x 8.
- Formula: D(mm) = √L(kg)
What is a good factor of safety?
General recommendations
| Applications | 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 | 1.5 – 2 |
Why do we need factor of safety?
A factor of safety increases the safety of people and reduces the risk of failure of a product. When it comes to safety equipment and fall protection, the factor of safety is extremely important. If a structure fails there is a risk of injury and death as well as a company’s financial loss.
How does Safety Factor work?
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 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 safety factor of motor?
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.
What is the purpose of using factor of safety 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 power factor of a motor?
Power factor (PF) is the ratio of working power, measured in kilowatts (kW), to apparent power, measured in kilovolt amperes (kVA). Apparent power, also known as demand, is the measure of the amount of power used to run machinery and equipment during a certain period.
What is service factor?
In simple terms, the service factor is the ratio of the gearbox rated horsepower (or torque) to the application’s required horsepower (or torque). Service factors are defined by the American Gear Manufacturers Association (AGMA), based on the type of gearbox, the expected service duty, and the type of application.
What is Motor SFA?
Service Factor Amps, or S.F.A., represents the amount of current the motor will draw when running at the full Service Factor. In the example nameplate, the S.F.A. is eight amps at 230 volts. Continually exceeding the S.F.A. shown on the nameplate can shorten motor life.
What is motor full load current?
Definition of ‘full load current’ A full load current is the largest current that a motor or other device is designed to carry under particular conditions. The starters shall be suitably rated to continuously carry the full load current of the motor and also accept the starting current surges without tripping.
How is motor Fla calculated?
The motor FLA calculator uses the following formulas:
- Single Phase AC Motor FLA (Amperes) = (P [kW] × 1000) / (V × cos ϕ)
- Single Phase AC Motor FLA (Amperes) = (P [HP] × 746) / (V × cos ϕ × η)
- Three Phase AC Motor FLA (Amperes) = (P [kW] × 1000) / (V × 1.732 × cos ϕ)
How do you read a motor nameplate?
The RPM listed on the nameplate is the shaft speed for the motor. The speed of the motor is directly related to the frequency of the line voltage and the number of poles in the motor. At 60 Hz, a 4 pole motor will rotate at approximately 1800 RPM (7200/4 poles).
How do I calculate horsepower?
Power = (Force x Distance) / Time For electric motors, power or horsepower can be calculated from the torque and speed. For example, if you have a motor rated for 3,000 RPM and 6 in-lbf then the horsepower is calculated below.
How do you read a pump nameplate?
Read Submersible pump nameplate details:
- Open well submersible pump set:
- Electrical details:
- 1ph: 1ph means the motor runs on single phase power supply, the motor inside the submersible pump can be run by applying single phase power supply.
- 220V: This is The maximum voltage applied across motor terminal.
- 2800 RPM: RPM means Revolution Per Minute.
How do you calculate the service factor of a motor?
Multiply your motor horsepower by the service factor. For example, if you have a 1HP motor and your service factor is 1.25, then you can operate safely at an HP = 1.25HP without overheating or damaging the motor.
How do you find RPM?
To calculate RPM for an AC induction motor, you multiply the frequency in Hertz (Hz) by 60 — for the number of seconds in a minute — by two for the negative and positive pulses in a cycle. You then divide by the number of poles the motor has: (Hz x 60 x 2) / number of poles = no-load RPM.
What is a pump service factor?
Generally, service factor is the measurement used to determine the peak performance at which a pump motor can operate. The National Electrical Manufacturers Association (NEMA) defines service factor simply as a multiplier that indicates the amount of additional load a motor can handle above its nameplate horsepower.
What should motor overloads be set at?
2) Thermal Overload Set Incorrectly-The basic requirement for overload protection setting for motors is 125% of their full-load current according to the NEC; however, it makes sure you read the overload relay instructions.
What must be done before a motor overload can be reset?
Check the motor starter contactor, the fuses, and the overload relay. 4) Rectify the root cause of overload and reset the overloads by push the reset button. Start the motor and check the running motor amps and compare to rated FLA and overload heater size using a clamp-on ammeter.
What is the full load current of a 1 hp motor?
Three Phase Motors
| MOTOR RATING | HP | APPROX. F.L.C. AT LINE VOLTAGE |
|---|---|---|
| 0.56 kW | 3/4 | 3.1 |
| 0.75 kW | 1 | 3.5 |
| 1.1 kW | 1.5 | 5 |
| 1.5 kW | 2 | 6.4 |
What can cause a motor to overload?
Motor overloading can be caused by an increase in the load being driven by the motor, bearing failure in the motor or the driven load, or an electrical problem such as a low input voltage or single phasing.
What is the purpose of an overload?
Overload relays protect a motor by sensing the current going to the motor. Many of these use small heaters, often bi-metallic elements that bend when warmed by current to the motor. When current is too high for too long, heaters open the relay contacts carrying current to the coil of the contactor.
Why starting current of motor is high?
When 3 phase voltage applied across the stator winding for starting of induction motor, high inrush currents magnetize the air gap between the stator and rotor. An induces emf is generated in the rotor windings of the induction motor because of the rotating magnetic field.
How do you check motor overload?
Overload Protection Test:
- Measure the normal motor running current (i motor).
- Turn off the motor and let it cool for about 10 minutes.
- Calculate the following ratio: i (motor) / i (overload min FLA).
- Set the overload to its minimum FLA and turn on the motor.
- Wait for the overload to trip.