Service Factor - Pertains to self-cooled motors. A measurement which states the percent horsepower the motor can carry beyond its nameplate rating and remain selfcooled. A service factor of 1.3 has a 30% horsepower margin built into the motor. Short - This is a condition in the motor windings or conductors where the absence of insulation causes currents to by-pass their normal circuit path. Sleeve-Bearing - A sleeve style bushing used to support a rotor in a motor. This style provides quiet motor operation as compared to ball bearings. Slip - A term describing the difference between the rotor speed and the speed of the motor’s rotating magnetic field. Rotors always drag behind the speed of a magnetic field. Slot Insulation - Also called Slot Liner. The insulation material used in the stator slots to protect the motor windings from scraping the laminations. It also provides winding protection against grounding to the laminations. Special Purpose Motor - Designed for a specific application. Developed when an OEM has refined the operating characteristics or construction features of the motor. Does not have standard operating characteristics or standard mechanical features. Squirrel Cage Blower / Centrifugal Blower / Forward Curve Blower - Air-moving devices consisting of a wheel made of many fins. The wheel is contained within a housing. Stack - Thickness of a motor stator. Starting Torque - The amount of turning force produced by a motor as it begins to turn from a standstill. Also called locked rotor torque. Static Balancing - Balancing without rotation. Static Pressure - The amount of resistance a system introduces to an air mover like a blower or fan blade. A blower seldom operates at free air. It generally is installed in a system that naturally creates resistance to air flow. The measured resistance is called static pressure. Fans and blowers are designed to deliver

 

 

Stator - The stack of iron laminations on which the coils are wound. Strobe - An RPM measuring device that flashes light pulses at a rotating shaft. The pulses are adjusted until an optical illusion of the shaft standing still is obtained. At this point, the RPM reading is taken. Submersible Motor - A motor whose housing is designed so that the motor can run under water; completely submerged. These are commonly used in water pumps. Synchronous Motor - A motor that runs at synchronous speed without slip. Tachometer - RPM measuring device. Temperature Rise - Amount of heat a motor generates above the ambient temperature. Torque - The twisting or turning force produced by the motor shaft. Voltage - The measure of electromotive force that causes current to flow in a circuit. UL (Underwriter’s Laboratories) - An agency who establishes safety standards for manufacturers to adhere to. Watts Output - The measure of mechanical power available from a motor. 746 watts equals one horsepower.