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Overview of Motor


Type Of Motor

Category according to phase

The motor can be categorized in several ways, but generally it is divided into a single-phase and a three-phase motor depending on how many phases the electrical source provides.

Single-Phase Motor
  • The single-phase electrical source is a commercial power source for the household electricity and represents one phase.
  • Since the electrical source alone can not make a motor rotate, a condenser should be connected to the auxiliary coil to operate the motor.
Three Motor
  • The three-phase motor stands for electrical power and it is consisted of three electrical sources with a phase offset of 120 degrees in voltage.
  • When the motor is connected to the electrical source, the magnetic field is generated and the motor starts rotating easily.
  • The motor efficiency is high and the torque is also relatively big.
Category according to function

Functionally, the motor can be grossly divided into three types.

Motor of Constant Speed
INDUCTION MOTOR
  • This is for one-direction operation.
  • This is a representative model for small AC motors and possible to use continuously.
  • There are two kinds: one is an induction motor with a condenser for single-phase and the other is an induction motor for three-phase.
  • There are two types a lead-wire type and a terminal-box type.
REVERSIBLE MOTOR
  • This is an induction motor run by a condenser for single-phase.
  • The external appearance is almost like that of an induction motor, but it is suitable for such operation that changes the rotational direction frequently from normal to reverse, and vice versa, because a temporary brake is inserted inside the motor to facilitate the reverse rotation.
  • There are two types a lead-wire type and a terminal-box type.
Motor width Brake Function
ELECTROMAGNETIC BRAKE ATTACHED MOTOR
  • This is a motor that has a fail-safe electromagnetic brake.
  • The reliable control function guarantees the stability of the motor.
  • Since the brake function is activated when the electrical source is off, this motor can be used safely even if the electricity fails.
Motor width Speed Controlling
Function
UNIT TYPE
  • This type of motor is easy to use with easy connection between a speed controller and a motor.
CONTROL PACK TYPE
  • The speed controller and the motor are separated. Therefore the speed controller and the motor can be separately selected based on the requirements, purposes of use, and so on.

Characteristic Of Motor

Definition of Motor
  • The motor is a device that converts electrical energy to dynamic energy.
  • The motor plays a critical roles as a heart of a machine.
Characteristic Of Motor

When an electrical connection is established to this motor, it spins and you can access the power source easily, and it is currently used for various purposes, including household and industrial appliances,as well as in the automation of production lines.

Wide Variety Of Motors
  • The size ranges are from 60mm/6w to □104mm/200w and there are various and rich assortment of models, including induction motor, reversible motor, electromagnetic brake, terminal box, speed controller, electronic brake, etc.
  • The operating voltage also covers the worldwide standards including 100V 50/60Hz (Japan), 200V 50/60Hz (Japan), 110V 60Hz (Taipei), 220V 60Hz (Korea, China), 115V 60Hz (North America), 230V 50Hz (Europe, Oceania), 220V-240V 50Hz (Southeast Asia), and so forth.
Low Noise and Low Vibration
  • Higher quality requirements for the motor in relation with place and condition of use ask for low noise and low vibration.
  • The operating voltage also covers the worldwide standards including 100V 50/60Hz (Japan), 200V 50/60Hz (Japan), 110V 60Hz (Taipei), 220V 60Hz (Korea, Taipei), 115V 60Hz (North America), 230V 50Hz (Europe, Oceania), 220V-240V 50Hz (Southeast Asia), and so forth.
Ease of Use
  • The design and production of the motor and the gear box can be customized to the user's specifications. So the user can use it safely and easily.
  • It is easy for a single-phase motor to operate to obtain the source of motive power simply by connecting condenser to the commercial electrical source, which is available at any place around the world. Since the condenser is not needed for a three-phase electrical source, the motor use can be directly connected without the condenser to a three-phase electrical source to obtain dynamic force.

Glossary of Motor-related

Electrical Source
AC
(AC : Alternating Current)
  • An alternating current is a current which changeslevel and direction periodically within a certain period of time.
    A sine wave is the most typical alternating current.
DC
(DC :Direct Current)
  • The direct current is an electrical current that has a positive (+) and a negative (-) fixed electrical sources like battery. Therefore the direction and magnitude of the direct current are constant.
  • The examples of a direct current installation include dry batteries, storage batteries, direct current generators, and various rectifiers.
Frequency
  • The frequency is the number of complete alternations of an alternating current per second.
  • The unit of the frequency is represented by Hertz (Hz).
  • In Korea, 60Hz is adopted as a standard frequency, which means the alternating current alternates 60 times per second between positive (+) and negative (-) electrical magnitudes.
Rating
  • The motor should be designed as to comply with the specified requirements, and the limit of its use under such a design is called rating.
  • Just as there are ratings specifying the limit as to how much output can be used, there are also rating specifications for voltage, current, number of rotations, and frequency. These are called rated output, rated voltage, rated current, rated number of rotations, and rated frequency.
  • The ratings are divided into a continuous rating, an intermittent rating, and an interactive rating. The INDUCTION MOTOR we manufacture belongs to a continuous rating. Our REVERSIBLE MOTOR is an intermittent rating (30 minutes).
Continuous Rating
  • When the rated load is imposed under the rated voltage and frequency, the continuous rating means that it can guarantee the continuous operation which will not result in exceeding the specified temperature and comply with the other requirements.
    The induction motor usually falls under the continuous ratingcategory.
Intermittent Rating
  • When the rated load is imposed under the rated voltage and frequency, the intermittent rating means the operation within a specified period of time will not result in exceeding the specified temperature and comply with the other requirements.
    There are 6 standard short-time rating including 5 minutes, 10 minutes, 15 minutes, 30 minutes, 1 hour and 2 hours.
Interactive Rating
  • When a motor is used with the rated load under the rated voltage and frequency, the interactive rating means that the cyclic operations of stopping and running with a certain load will not result in exceeding the specified temperature and comply with the other requirements.
Output

The output is an amount of work accomplished by the motor in unit time and it is represented by the product value of the revolutions and the torque. The rated out is indicated in the motor.

Output = 1.027 x T x N [WATTS]

  • 1.027 : Fixed Number, T : Torque(kg·m), N : Revolutions per minute (rpm)
  • 1 Horse Power (HP) is 746 (Watts).
  • Rated Output : The rated output is a continuously generated output under the specified voltage and frequency. In general, the rated output at this time is called an output of the motor.
Torque and Numbers Of Rotations

The torque of the motor is a rotating torque that makes a rotor start working and the unit is [g · cm] or [kg · cm]. [N.m] [oz·in], [lb·in] is used by countries.

[1kg·cm = 0.0981 N·m = 98.1 mN·m = 13.9oz·in = 0.868 lb·in]

The torque of 1 kg · cm is the same as the rotating torque when 1kg of the force is added perpendicularly to a point in the output sphere of 1cm-radius rotor.

Starting Torque (① in Fig)

  • This is a torque when the motor is starting. It is also referred to as a locked rotating torque.
  • If a force greater than the starting torque is applied to the motor, the motor will not work.

Stalling Torque (② in Fig)

  • This is a maximum torque that the motor can supply.
  • If a load greater than the maximum torque is applied to the motor, the motor will stop.

Rated Torque (③ in Fig)

  • This is a torque when the motor operates at the rated speed.
  • This is also a torque when the motor generates a rated output continuously with the rated voltage.

Synchronous Revolutions (④ in Fig)

  • This is the number of rotations determined by the frequency of the power source and the number of poles in the motor.
  1. Ns : Synchronous revolutions per minute (rpm)
  2. P : Number of poles in a motor
  3. f : Frequency of a power source [Hz]
  4. 120 : Fixed Number
  5. rpm : Number of revolutions per minute Example)

Example) If the motor has 4 poles and the power source frequency is 60Hz.

And if the motor has 4 poles and the power source frequency is 50Hz,

No-load Revolutions (⑤ in Fig)

  • This is the number of revolutions when the motor is operating while no load is imposed on the output axis. In case of an induction motor or a reversible motor, the number of revolutions is less by 20 - 80 [rpm] than the number of synchronous revolutions.

Rated Revolutions (⑥ in Fig)

  • This is the number of revolutions when the motor is operating with the rated load for generating the rated output. This is an ideal number of revolutions for use.

SLIP

  • This is an another way of expressing the number of revolutions and it is represented by the following equation.
  1. Ns : Synchronous revolutions per minute [rpm]
  2. N : Revolutions per minute under an arbitrary load [rpm]
  3. S : Slip

Example) If an induction motor of 4 poles and 60Hz is operating with a slip S = 0.1,

Static Torque

The static torque is a torque experienced when a load is being imposed while the electromagnetic brake and the clutch brake are stopped.

허용 Torque

The ambient torque is a maximum torque allowable to use when the motor is operating. This torque has a limitation by the rated torque, the temperature-rise, and the strength of the assembled gearhead.

Over Run

This is an excessive number of revolutions, expressed as angular degrees, that the motor makes from the moment of power shut-off until the motor stops.

Gear head
Gear Ratio
  1. This is a ratio that the gearhead decelerates the number of rotations of the motor.
  2. The number of rotations of the motor at the output axis of the gearhead is 1/Gear Ratio. The gear ratio has tow kinds of rates in order to make the number of rotations of gearhead's output shaft in the motor between 50Hz and 60Hz equal each other. The one set of ratios are 3, 5, 7.5, 12.5, 15 ... and the other set ratios are 1.2 times of the former set, that is, 3.6, 6, 9, 15, 18, ...
  3. RPM of gearhead output shaft is almost the same as the case of 3 for the reduction gear ratio in the 50Hz region and the case of 3.6 for the reduction gear ratio in the 60Hz region.
  4. Naturally, any gearhead is allowed to use either in 50Hz area or 60Hz.
Maximum Ambient Torque
  1. This is a torque with a maximum load imposed on the gearhead.
  2. Since it is decided by mechanical strength such as the material, size of gear and bearing used in the gearhead,
    it varies according to the type of gearhead and reduction gear ratio.
Service Factor
  1. This is a coefficient used to estimate the lifetime of the gearhead.
  2. This is an empirically determined value based on the results of the lifetime test conducted under the given load and the conditions of use.
Delivery Efficiency Rate
  1. This is an efficiency rate when the torque is amplified by connection the gearhead to the motor and it is represented by percentage(%). It is determined by the resistance of the lubricant as well as the friction of pinion and gear used with the gearhead.
  2. The delivery efficiency rate is 90% for each gear. Therefore it would have efficiency rate, 81% for the 2nd gear, 73% for the 3rd gear, 66% for the 4th gear, 59% for the 5th gear. If gear ratio is higher, the number of gear will increase and the efficiency rate will decrease.
Over Load
  1. This is a load received vertical to the gearhead's output shaft.
  2. The maximum overhung load at the gearhead is called the ambient overhung load.
    The value varies depending on the type of the gearhead and the distance from the end of the shaft to the gearhead.
Thrust Load
  1. This is a load received horizontal to the gearhead's output shaft.
  2. The maximum thrust load at the gearhead is called the ambient thrust load. The value varies depending on the type of the gearhead.

Motor Temperature Rise

Motor Temperature Rise and Insulation
  • When the motor operates, heat will be generated.
    This is an electrical loss resulting from copper loss that occurs on the current-carrying element of the motor, due to resistance from the coil or conductor,and resistance of iron core material when magnetic flux lines run,and iron loss occurred on the iron core in order to magnetize it.
  • The heat is generated by the frictional loss and the machanical loss caused by the air friction, etc.
  • Some of the heat generated in the motor is accumulated inside the motor, and the rest is released to the outside by means of radiation, convention, and conduction.
  • While the motor is running, the temperature difference between the heat loss generated inside the motor and the heat released to the outside of the motor is referred to as a temperature rise.
  • While the motor is running, the heat is generated and as a result the temperature rises, and the part that has the highest temperature in the motor is a winding section. Therefore, the use of the motor is restricted from the ambient temperature as well as the temperature of the motor itself.
  • The limitations on use of a motor by the insulation class are shown in the table below.
Type of Insulation Description Max. Allowable
Temperature		 Remark
Class Y Made of materials like cotton, silk, and paper. Materials not impregnated in varnishes or oils. 90ºC
Class A Made of the same kinds of materials as described in Class Y. Materials impregnated in varnishes or oils 105ºC
Class E Polyurethane resin for enamel wire, epoxy resin, accumulated cotton material, and accumulated paper material. 120ºC
Class B Materials made of mica, asbestos, glass fiber using adhesive agent. 130ºC
Class F Made of the same kinds of materials as described in Class B using adhesive agent such as silicon alkaloid resin, etc. 155ºC
Class H Made of the same kinds o materials as described in Class B and F with silicon resin or equivalent materials. 180ºC
Class C Made solely by original mica, asbestos, or ceramic, or together with adhesive agent. 180ºC 초과
  • Since motor temperature increases during its operation, it is recommended to not exceedan outdoor temperature of 90 ℃, and it should be used within a range that itstemperature does not exceeditsmaximum permissibletemperature.
  • Most of our motors belong to Class E, while the motor for UL certification is Class A. If the induction motor is running continuously for 2 to 3 hours since it is started, its temperature may reach a saturation point and since then, the temperature stays constant below the specified maximum allowable temperature. The reversible motor is rated for 30 minutes continuous operation, but the operating time cam be varied depending on the load and the operating mode (how often the operation is on and off, and so on). Therefore, if the motor is used at the temperature below the specified maximum allowable temperature, the operating hours can be extended.
Ambient Tempereature

It is advised to use the motor at the ambient temperature between -10℃ and +40℃. If the motor is operating in an environment of the temperature higher than the maximum ambient temperature or inside a house, the heat emitted by the increased temperature of the motor is added to the ambient temperature so that the lifetime of the winding coil and the ball bearing shortens significantly. The operation of the motor in a too low temperature environment also causes problems associated with starting of the motor. In addition, the decrease of the interrelative influence of the gearhead's lubricating grease and the ball bearing causes the frictional torque to be increased. As a result, the motor does not get started or takes longer time to start.

Method to measure a motor temperature increases

A thermocouple of temperature multipoint reorder is attached at the center of the housing (the motor case) in order to check the housing temperature saturation caused by the heat the motor releases. The difference of the saturated temperature and the ambient temperature is called a temperature rise and the unit of th temperature is deg. In general, the part that has a highest temperature in the motor is a winding section. The maximum ambient temperature of the winding section is specified as K.S. standards for each type of insulation material.

  • The temperature rise can be derived rom the following equation.
  1. R1 : Resistance of winding before the temperature rise test
  2. R2 : Resistance of winding after the temperature rise test
  3. T1 : Ambient temperature before the temperature rise test
  4. T2 : Ambient temperature after the temperature rise test
  5. 234.5 : Temperature coefficient of the copper wire
  • The temperature of the motor rises further if the motor is frequently stopped and re-started, or the direction of the rotation is frequently reversed, or the instantaneous stoppage is frequent. The lower the temperature of the motor is, the longer the lifetime of the motor.
  • During the operation of the motor, the temperature of the housing (motor case) surface may rise or go up above 90℃, but it is not an anomaly. Thus, care should be taken, because careless touching of the motor or bringing of a flammable substance near to the motor may result in an accident.
Overheat Protection Device
Thermally
Protected
Device
  1. T.P which is the overheating protection device (Thermal Protection) device, which is an overheat protection device, in a winding section to protect the motor from being damaged when the motor is overheating or the temperature around rises during the operation. Especially, UL conformance products and CE marked products have a built-in T/P device. Our K7, K8, and K9, which are UL conformance motors and CE marked motors, have a built-in T/P device, and "Thermally Protected" sign is indicated in the name plate. If the T/P sign in the name plate is shown in the motor intended for the domestic market, it has a built-in T/P.
  2. This T/P employed a heat sensing bimetal to facilitate the opening and closing of the contact point. This is an automatic reset type, meaning that it shuts off the circuit when an abnormal temperature is detected and that it returns to the original state when the temperature returns to a normal level.
IMPEDANCE
PROTECTED
TYPE
  1. The impedance protected motor is designed to increase the impedance of the winding to reduce the increment of (input) current in order to prevent the temperature from rising up above the maximum ambient temperature even when the motor is restrained.
  2. The sign "Impedance Protected" or "ZP" is shown in the name plate of the motor. The UL certified model of our K6 motor belongs to this category.
  • Contacts
    CEO : Lee Young Sik, Business registration number : 740-81-00242
    Headquarters / 1st Factory : 226, Oksan-ro, Wonmi-gu, Bucheon-si, Gyeonggi-do, Republic of Korea
    TEL : +82 32-684-7791   FAX : +82 32-683-5059
    No. 2 factory : 180, Oksan-ro, Wonmi-gu, Bucheon-si, Gyeonggi-do, Republic of Korea
    TEL : +82 32-664-7790   FAX : +82 32-611-7791
  • E-mail
    ggm@ggm.co.kr