Glossary
# A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
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"C" FLANGE A type of flange used with close coupled pumps, speed reducers, and similar applications where the mounting holes in the f flange are threaded to receive bolts. Normally the "C" Flange is ...
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"D" FLANGE A special end shield with holes for through bolts in the flange and is primarily used for mounting the motor on gear boxes or bulkheads. Standardized for frames 143T through 445T. "D" flan...
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A
AC (ALTERNATING CURRENT) The commonly available electric power supplied, an AC generator and is distributed in single or three-phase forms. AC current changes its direction of flow (cycles).
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AC MOTORS A Motor (see motor definition) operating on AC current that flows in either direction (AC current). There are two general types: Induction, and Synchronous.
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Accidental Means Unexpected or undesigned cause of an accidental bodily injury. Under a definition of accidental means, the mishap itself must be accidental, not just the resulting injury.
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ACTIVE IRON The amount of steel (iron) in the stator and rotor of a motor. Usually the amount of active iron is increased or decreased by lengthening or shortening the rotor and stator (they are gen...
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Actuary A specialist in the mathematics of insurance who calculates rates, reserves, dividends and other statistics
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Adjuster A representative of the insurer who seeks to determine the extent of the insurer's liability for loss when a claim is submitted
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Air Filtration System System that cleans smog, pollen, exhaust, smoke and odors out of the air. Cleans both interior circulated air and that coming from the outside.
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AIR GAP The space between the rotating (rotor) and stationary (stator) member in an electric motor.
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AIR PRESSURE SWITCH Used on motors with blowers to measure the difference in pressure across the filter so as to detect a clogged filter.
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AIR TEMPERATURE SWITCH A device used in air hooded motors to detect the temperature of the exhausted air. When used in this manner an air temperature switch will detect blockage in the cooling air sy...
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ALTITUDE The atmospheric altitude (height above sea level) at which the motor will be operating; NEMA standards call for an altitude not exceeding 3,300 ft. (1,000 meters). As the altitude increases ...
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AMBIENT TEMPERATURE The temperature of the surrounding cooling medium, such as gas or liquid, which comes into contact with the heated parts of the motor. The cooling medium is usually the air surro...
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ANTI-FRICTION BEARING An anti-friction bearing is a bearing utilizing rolling elements between the stationary and rotating assemblies.
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Anti-Lock-Braking System A braking system that senses when any of the wheels have locked up, or are about to, and automatically reduces the braking forces to keep the wheels rolling. Commonly called...
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ARMATURE The portion of the magnetic structure of a DC or universal motor which rotates
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ARMATURE CURRENT, AMPS Rated full load armature circuit current.
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ARMATURE INDUCTANCE, MH Armature inductance in milli-henries (saturated).
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ARMATURE REACTION The current that flows in the armature winding of a DC motor tends to produce magnetic flux in addition to that produced by the field current. This effect, which reduces the torque ...
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ARMATURE RESISTANCE, OHMS Armature resistance is measured in ohms at 25ƒ C. (cold)
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AXIAL THRUST The force or loads that are applied to the motor shaft in a direction parallel to the axis of the shaft. (Such as from a fan or pump)
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B
BACK END OF A MOTOR The back end of a normal motor is the end which carries the coupling or driving pulley. (NEMA) This is sometimes called the drive end (D.E., pulley end P.E.) etc.
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BASE SPEED, RPM The speed which a DC motor develops at rated armature and field voltage with rated load applied.
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BEARING LIFE Rating life, L10 (Bl0), is the life in hours or revolutions in which 90% of the bearings selected will obtain or exceed. Median life (average life), L50(B50)
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BEARINGS Are used to reduce friction and wear while supporting rotating elements. For a motor it must provide a relatively rigid support for the output shaft.
The bearing acts as the connection poi...
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BRAKES An external device or accessory that brings a running motor to a standstill and/or holds a load. Can be added to a motor or incorporated.
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BRAKING TORQUE The torque required to bring a motor down to a standstill. The term is also used to describe the torque developed by a motor during dynamic braking conditions.
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BREAKDOWN TORQUE The maximum torque a motor will develop at rated voltage without a relatively abrupt drop or loss in speed.
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Broker Insurance salesperson that searches the marketplace in the interest of clients, not insurance companies.
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BRUSH A piece of current conducting material (usually carbon or graphite) which rides directly on the commutator of a commutated motor and conducts current from the power supply to the armature windi...
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C
CANOPY (DRIPCOVER) A protective cover placed on the top of a motor being mounted vertically to protect it from liquids or solids that might drop onto the motor. (It acts similar to an umbrella for th...
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CAPACITOR A device which, when connected in an alternating-current circuit, causes the current to lead the voltage in time phase. The peak of the current wave is reached ahead of the peak of the volt...
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CAPACITOR MOTOR A single-phase induction motor with a main winding arranged for direct connection to the power source, and auxiliary winding connected in series with a capacitor. There are three type...
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CAPACITOR START The capacitor start single phase motor is basically the same as the split phase start, except that it has a capacitor in series with the starting winding. The addition of the capacito...
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Carburetor The fuel system component that meters the fuel and air and supplies the proper amounts of both to the engine. The part of the engine that handles the job of changing ratios or air and fue...
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CENTRIFUGAL CUTOUT SWITCH A centrifugally operated automatic mechanism used in conjunction with split phase and other types of single phase induction motors. Centrifugal cutout switches will open or ...
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Chassis A general term that refers to all of the mechanical parts of a car attached to a structural frame. In cars with unitized construction, the chassis comprises everything but the body of the ca...
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CLUTCH A mechanical device for engaging and disengaging a motor often used when many starts and stops are required.
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COGGING A term used to describe non-uniform angular velocity. It refers to rotation occurring in jerks or increments rather than smooth motion. When an armature coil enters the magnetic field produce...
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COIL (Stator or Armature) The electrical conductors wound into the core slot, electrically insulated from the iron core. These coils are connected into circuits or windings which carry independent cu...
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Commercial Travelling For use in connection with any business or trade that involves buying or selling of any description. For example, a Company Representative, Door-to-door salesperson or Insurance...
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COMMUTATOR A cylindrical device mounted on the armature shaft and consisting of a number of wedge-shaped copper segments arranged around the shaft (insulated from it and each other. The motor brushes...
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COMPOUND WOUND DC MOTORS Designed with both a series and shunt field winding, the compound motor is used where the primary load requirement is heavy starting torque, and adjustable speed is not requi...
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Compulsory Excess This is the amount that has been your insurer has stated to be a requirement. It varies according to the terms of cover provided.
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CONDUCTOR A material, such as copper or aluminum, which offers low resistance or opposition to the flow of electric current.
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CONDUIT BOX The metal container usually on the side of the motor where the stator (winding) leads are attached to leads going to the power supply.
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CONSTANT H.P. A designation for variable or adjustable speed motors used for loads requiring the same amount of H.P. regardless of their motor speed during normal operation.
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CONSTANT SPEED A DC motor which changes speed only slightly from a no load to a full load condition. In AC motors, these are synchronous motors.
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CONSTANT TORQUE Refers to loads whose H.P. requirements change linearly with changing speeds. Horsepower varies with the speed, i.e.- 2/1 HP at 1800/900 RPM. (Seen on some 2-speed motors). Possible a...
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Convictions Convictions subject to the Rehabilitation of Offenders Act (ROOA) have to be declared to the Insurer otherwise your policy cover could be voided. Any criminal convictions, including motor...
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CORE The iron portion of the stator and rotor; made up of cylindrical laminated electric steel. The stator and rotor cores are concentric separated by an air gap, with the rotor core being the smalle...
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COUNTER ELECTROMOTIVE FORCE(CEMF) The induced voltage in a motor armature, caused by conductors moving through or "cutting" field magnetic flux. This induced voltage opposes the armature current and ...
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COUPLINGS The mechanical connector joining the motor shaft to the equipment to be driven.
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Cover Notes A temporary document which acts as a certificate of insurance. This meets the requirements of the Road Traffic Act (RTA).
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Crankshaft A shaft with one or more cranks, or "throws," that are coupled by connecting rods to the engine's pistons. Together, the crankshaft and the con rods transform the pistons' recipro...
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CURRENT The time rate of flow of electrical charge and is measured in amps (amperes).
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CYCLES PER SECOND (HERTZ) One complete reverse of flow of alternating current per rate of time. (A measure of frequency.) 60 HZ (cycles per second) A.C. power is common throughout the U.S. and 50 HZ ...
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D
D.C. (DIRECT CURRENT) A current that flows only in one direction in an electric circuit. It may be continuous or discontinuous and it may be constant or varying.
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DC MOTOR A motor using either generated or rectified D.C. power. A DC motor is usually used when variable speed operation is required.
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DEFINITE PURPOSE MOTOR A definite purpose motor is any motor design, listed and offered in standard ratings with standard operating characteristics with special mechanical features for use under serv...
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DIMENSIONS NEMA has standard frame sizes and dimensions designating the height of the shaft, the distance between mounting bolt holes and various other measurements. The integral AC motor NEMA sizes ...
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DRIP-PROOF GUARDED A drip-proof machine with ventilating openings guarded (with screens) as in a guarded motor.
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DRIP-PROOF MOTOR An open motor in which the ventilating openings are so constructed that drops of liquid or solid particles falling on it, at any angle not greater than 15 degrees from the vertical, ...
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DUAL TORQUE Dual speed motor whose torque varies with speed (as the speed changes the horsepower remains constant).
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DUAL VOLTAGE Some motors can operate on two different voltages, depending upon how it is built and connected. The voltages are either multiples of two or the 3 of one another.
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DUTY CYCLE The relationship between the operating and rest times or repeatable operation at different loads. A motor which can continue to operate within the temperature limits of its insulation syst...
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DYNAMOMETER A device which loads the motor to measure output torque and speed accurately by providing a calibrated dynamic load. Helpful in testing motors for nameplate information and an effective d...
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E
Endorsements (a) Any time you change your policy after first taking it out, the document you receive from your insurer showing the mid-term changes is called an endorsement.
(b) Another definition...
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Excess This is the part of every claim which you must pay with your own money.
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Exhaust The system of exhausting the burned gases from an internal-combustion engine consisting of piping or tubing, silencers, and, at times, resonators.
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F
FIELD A term commonly used to describe the stationary (Stator) member of a DC Motor. The field provides the magnetic field with which the mechanically rotating (Armature or Rotor) member interacts.
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FIELD WEAKENING The introduction of resistance in series with the shunt wound field of a DC motor to reduce the voltage and current which weakens the strength of the magnetic field and thereby increa...
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FLANGE Mounting endshield with special rabbets and bolt holes for mounting such equipment as pumps and gear boxes to the motor or for overhanging the motor on the driven machine.
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FLUX The magnetic field which is established around an energized conductor or permanent magnet. The field is represented by flux lines creating a flux pattern between opposite poles. The density of t...
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Foreign Use On a motor insurance policy this refers to when the vehicle is used abroad. Watch out, as not all Insurers cover you whilst abroad. Even if your insurance certificate states that it cover...
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FORM FACTOR A figure of merit which indicates how much rectified current departs from pure (non-pulsating) DC. A large departure from unity form factor (pure DC, expressed as 1.0) increases the heati...
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FORM WOUND A type of coil in which each winding is individually formed and placed into the stator slot. A cross sectional view of the winding would be rectangular. Usually form winding is used on hig...
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Four-Wheel Steering A steering system that actively steers the rear wheels as well as the fronts to improve handling and maneuverability.
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FRACTIONAL-HORSEPOWER MOTOR A motor usually built in a frame smaller than that having a continuous rating of one horsepower, open construction, at 1700 -1800 rpm. Within NEMA frame sizes FHP encompas...
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FRAME The supporting structure for the stator parts of an AC motor; in a DC motor the frame usually forms a part of the magnetic coil. The frame also determines mounting dimensions (see frame size).
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FRAME SIZE Refers to a set of physical dimensions of motors as established by NEMA. These dimensions include critical mounting dimensions. 48 and 56 frame motors are considered fractional horsepower ...
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FREQUENCY The rate at which alternating current makes a complete cycle of reversals. It is expressed in cycles per second. In the U.S. 60 cycles (Hz) is the standard while in other countries 50 Hz (c...
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FRONT END OF A MOTOR The front end of a normal motor is the end opposite the coupling or driving pulley. (NEMA) This is sometimes called the opposite pulley end (O.P.E.) or commutator end (C.E.).
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Fuel Injection Any system that meters fuel to an engine by measuring its needs and then regulating the fuel flow, by electronic or mechanical means, through a pump and injectors. Throttle-body injec...
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FULL-LOAD CURRENT The current flowing through the line when the motor is operating at full-load torque and full-load speed with rated frequency and voltage applied to the motor terminals.
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FULL-LOAD TORQUE That torque of a motor necessary to produce its rated horsepower at full-load speed, sometimes referred to as running torque.
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G
GEARHEAD The portion of a gearmotor which contains the actual gearing which converts the basic motor speed to the rated output speed.
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GEARMOTOR A gearhead and motor combination to reduce the speed of the motor to obtain the desired RPM's.
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GENERAL PURPOSE MOTOR A general-purpose motor is any motor having a "B" design, listed and offered in standard ratings with standard operating characteristics and mechanical construction for use unde...
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GROUNDED MOTOR A motor with an electrical connection between the motor frame and ground.
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GUARDED MOTOR An open motor in which all openings giving direct access to live or rotating parts (except smooth shafts) are limited in size by the design of the structural parts or by screens, grills...
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H
HEAT EXCHANGER A device which will transfer the heat from inside the motor to another medium, through a radiator type heat exchanger.
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HERTZ (HZ) One cycle per second (as in 60 Hz. which is 60 cycles per second).
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HORSEPOWER The measure of rate of work. One horsepower is equivalent to lifting 33,000 pounds to a height of one foot in one minute. The horsepower of a motor is expressed as a function of torque and...
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Horsepower The common unit of measurement of an engine's power. One horsepower equals 550 foot-pounds per second, the power needed to lift 550 pounds one foot off the ground in one second: or on...
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HYSTERESIS LOSS The resistance offered by materials to becoming magnetized (magnetic orientation of molecular structure) results in energy being expended and corresponding loss. Hysteresis loss in a ...
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I
Independent Suspension Any suspension in which the camber of a wheel is not directly affected by the vertical motion of the opposite wheel.
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Insurance Ombudsman This is the ombudsman for the insurance industry and to whom all complaints should be addressed if no satisfaction has been obtained from yourcompanyname or your Insurer. Please s...
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K
Knock-for-Knock An agreement whereby each motor insurer agrees to pay for damage to its policyholder's car, regardless of blame, providing the policy covered damage to the policyholder's own ...
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L
LAMINATIONS The steel portion of the rotor and stator cores made up of a series of thin laminations (sheets) which are stacked and fastened together by cleats, rivets or welds. Laminations are used i...
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LARGE MOTORS Usually refers to AC motors in 5,000 series frames and above and to 500 series frames and larger in DC.
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Left Hand Drive Vehicles Vehicles where the steering wheel is on the left, designed for countries where people drive on the right.
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Limits Ages below or above which the insurer will not issue a policy or above which it will not continue a policy presently in force.
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Lloyd's of London An insurance market organised into syndicates, which underwrites most types of policy.
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LOAD The burden imposed on a motor by the driven machine. It is often stated as the torque required to overcome the resistance of the machine it drives. Sometimes "load" is synonymous with "required ...
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LOCKED ROTOR CURRENT Steady state current taken from the line with the rotor at standstill (at rated voltage and frequency). This is the current seen when starting the motor and load.
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LOCKED ROTOR TORQUE The minimum torque that a motor will develop at rest for all angular positions of the rotor (with rated voltage applied at rated frequency).
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Loss Assessor This is an individual acting on behalf of policyholders in assessing claims.
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LOSSES A motor converts electrical energy into a mechanical energy and in so doing, encounters losses. These losses are all the energy that is put into a motor and not transformed to usable power but...
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LUBRICATION In order to reduce wear and avoid overheating certain motor components require lubricating (application of an oil or grease). The bearings are the major motor component requiring lubricat...
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M
MAGNETIC POLARITY It is a fundamental principle of a winding that adjacent poles must be wound to give opposite magnetic polarity. This does not mean that the coils actually have to be wound in this ...
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Main Bearings The bearings in an engine block that support the crankshaft.
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Mechanical Breakdown Insurance This cover protects against the cost of breakdowns of household appliances or motor vehicles.
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MEGGAR TEST A measure of an insulation system's resistance. This is usually measured in megohms and tested by passing a high voltage at low current through the motor windings and measuring the re...
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MOTOR A device that takes electrical energy and converts it into mechanical energy to turn a shaft.
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Motor Insurance This insurance covers legal liabilities arising from the use of a motor vehicle. Comprehensive policies also cover damage to the vehicle. The minimum legal cover in the UK is third pa...
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MULTI-SPEED MOTORS A motor wound in such a way that varying connections at the starter can change the speed to a predetermined speed. The most common multi-speed motor is a two speed although three- ...
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Mutual An insurance company that is owned by its policy holders.
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N
New-For-Old Cover for property where an item lost or destroyed would be replaced with a brand new one, with no deduction for wear and tear. Also called "replacement as new".
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No Claim Discount / Bonus A reduction in a renewal premium to reflect a claim-free record; used most often in motor insurance. Policyholders can typically build up to a 65% no claims bonus. Find more...
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O
OIL MIST LUBRICATION-DRY SUMP A method for lubricating anti-friction bearings which utilizes oil dispersed on an air stream. The mist is exhausted from the bearing housing so as not to permit oil to ...
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OIL MIST LUBRICATION-WET SUMP Similar to Oil Mist Lubrication - Dry Sump, except that a pool of oil is developed in the bearing chamber. This oil pool will continue to supply oil to the bearing in th...
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Oil Pan An oil pan is a bath-shaped reservoir located under the crankcase or cylinder block of an engine. The oil is stored in the oil pan when the vehicle is not running. When the engine is in oper...
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OPEN (PROTECTED) MOTOR A motor having ventilating openings which permit passage of external cooling air over and around the windings. The term "open machine", when applied to large apparatus without ...
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OPEN BEARING A ball bearing that does not have a shield, seal or guard on either of the two sides of the bearing casing.
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OPEN EXTERNALLY-VENTILATED MACHINE A machine which is ventilated with external air by means of a separate motor-driven blower mounted on machine enclosure.
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OPEN PIPE-VENTILATED MACHINE An open machine except that openings for admission of ventilating air are so arranged that inlet ducts or pipes can be connected to them. Air may be circulated by means i...
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P
PARALLELING When two or more DC motors are required to operate in parallel - that is, to drive a common load while sharing the load equally among all motors - they should have speed-torque characteri...
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PART WINDING START MOTOR Is arranged for starting by first energizing part of the primary winding and subsequently energizing the remainder of this winding in one or more steps. The purpose is to red...
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PHASE Indicates the space relationships of windings and changing values of the recurring cycles of A.C. voltages and currents. Due to the positioning (or the phase relationship) of the windings, the ...
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PLS An exclusive Reliance Electric bearing and lubricating system which permits complete lubrication of the bearing whether the motor is mounted vertically or horizontally. This system also helps pre...
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PLUG REVERSAL Reconnecting a motor's winding in reverse to apply a reverse braking torque to its normal direction of rotation while running. Although it is an effective dynamic braking means in m...
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POLARISATION TEST A ratio of a one-minute meggar test to ten-minute meggar test. Used to detect contaminants in winding insulation done typically on high voltage, V.P.I. motors which are tested by wa...
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Policy The insurance document providing full details of the contract between the insurer and the policyholder.
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Policyholder This is the person to which the insurer issues the policy. It normally also means the person to whom benefits are payable.
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Premium The price of insurance protection for a specified risk for a specified period of time.
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Protected No Claims Discount This means that you are entitled to make a claim or two without losing any of your no-claims discount and dropping down the scale.
Watch out though because not all In...
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S
Shock absorber A device that converts motion into heat, usually by forcing oil through small internal passages in a tubular housing. Used primarily to dampen suspension oscillations, shock absorbers...
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Spark Plug The spark plug converts high voltage energy into an arc that passes between its electrodes. The arc causes the gasoline-air mixture in the cylinder to ignite and expand, providing power b...
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T
Transmission A gearbox with a number of selectable ratios, used to match the engine's rpm and torque to differing vehicle requirements.
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U
Underwriter A technician trained in evaluating risks and determining rates and coverages for them. The term derives from the practice at Lloyd's of each person willing to accept a portion of the ...
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V
Voluntary Excess This is when you agree to pay a larger portion of each claim than the compulsory excess.
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W
Waiver An agreement attached to the policy and accepted by the insured, to eliminate a specified pre-existing physical condition or specified hazard.
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Windscreen Cover Windscreens are usually only covered under Comprehensive Private car policies and are subject to different excesses than the main policy. Damaged windscreens (i.e. scratched) may not...
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Write-Off A damaged car or vehicle which is not repairable, or one that would cost more to repair than the car was worth before the damage occurred. Also known as a "total loss". Often an insurance c...
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