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 meant by the service factor of an electric motor?
Service factor – SF – is a measure of periodically overload capacity at which a motor can operate without damaging. Sponsored Links. The service factor – SF – is a measure of periodically overload capacity at which a motor can operate without damage.
How do you calculate the service factor of a motor?
Calculate your operating or “effective” HP level. 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.
What is 1.15 service factor?
Motor “service factor” is probably the most misunderstood value on a motor nameplate. To most it seems quite simple; if it is a 1.0 you can run a motor to 100% load, if it is 1.15, then it can be loaded to 115% of its rated load.
Is a higher service factor better?
A motor operating continuously at any service factor greater than 1 will have a reduced life expectancy compared to operating at rated nameplate horsepower. Insulation life and bearing life are reduced by the service factor load.” … A much better choice for this application, however, would be a 125 hp (93 kW) motor.
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.
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 power factor means?
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 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 is the motor slip?
“Slip” in an AC induction motor is defined as:
As the speed of the rotor drops below the stator speed, or synchronous speed, the rotation rate of the magnetic field in the rotor increases, inducing more current in the rotor’s windings and creating more torque. Slip is required to produce torque.
Do all motors have a service factor?
Most motors have a duty factor of 1.15 for open motors and 1.0 for totally closed motors. Traditionally, totally enclosed fan cooled (TEFC) motors had an SF of 1.0, but most manufacturers now offer TEFC motors with service factors of 1.15, the same as on ODP motors.
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 S1 duty in motor?
(Figure 1) Motor Duty Cycle #1 – Continuous Duty. The first, and simplest, type of motor duty cycle is continuous duty. This is also referred to by its abbreviated name, S1 duty (Figure 1). In this type of operation, the motor runs with a constant load for a long enough duration so that it reaches thermal equilibrium.
What does service factor mean?
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 motor rotation is indicated by CCW OE?
The direction in which shaft rotates: CW-Clockwise; CCW-Counterclockwise; CW/CCW(Reversible), rotation can be changed by electrical reconnection.
What is 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.