Nippon Pulse Stepper Motor Basics

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Stepper Motor Basics

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Stepper Motors Sold & Serviced By: ELECTROMATE Toll Free Phone (877) SERVO98 Toll Free Fax (877) SERV099 www.electromate.com sales@electromate.com

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What is a Stepper Motor? • The stepper motor is a motor which takes input pulses and then takes proportional steps to input these signals. You can use for positioning and/or speed control for most any applications. The stepper motor needs a power circuit and a sequence circuit for changing phase. Sold & Serviced By: ELECTROMATE Toll Free Phone (877) SERVO98 Toll Free Fax (877) SERV099 www.electromate.com sales@electromate.com 2

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What is a Stepper Motor? <Stepper with Peripheral Construction> Vm (Motor Power) <Controller> CPU or Motion- Control-Chip Vcc (Logic power) 3 <Driver> Sequencer Power Tr. <Motor> Sold & Serviced By: ELECTROMATE Toll Free Phone (877) SERVO98 Toll Free Fax (877) SERV099 www.electromate.com sales@electromate.com

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What is a Stepper Motor? <Applications> • Medical: Infusion Pump, Brad Test, X-ray, Dialysis, DNA Extraction, Pump • Semiconductor: Masking, Etching, Wafer Handling, Test-equipment, Die-Bonder • FA: Pick & Place, NC Machine, X-Y-Z stage • OA: Printer, Fax, Scanner • HA: HVAC, Cleaner Robot • Other: Vending machine Sold & Serviced By: ELECTROMATE Toll Free Phone (877) SERVO98 Toll Free Fax (877) SERV099 www.electromate.com sales@electromate.com 4

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Stepper and Synchronous Motors Movement Generation • Step Mode • Torque Generation • Characteristics • Reduced Duty Cycle • Synchronous Motor Sold & Serviced By: ELECTROMATE Toll Free Phone (877) SERVO98 Toll Free Fax (877) SERV099 www.electromate.com sales@electromate.com 5

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Movement Generation S N S N S N § rotor follows the stator field § one step ⇒ invert magnetic field in 1 coil § for the next step invert magnetic field in the other coil § A stepper motor always needs electronic control. Sold & Serviced By: ELECTROMATE ) SERVO98 § step angle depends on number of poles -> fixed by constr TToll Free Faxe(877) SERV099 www.electromate.com sales@electromate.com 6

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Movement Generation Unipolar Principle • motor coils are unipolar • every coil end has only one polarity (”+” or ”ground (-)”) PhA1 (=open) + PhA2 (=GND) S N Sold & Serviced By: ELECTROMATE Toll Free Phone (877) SERVO98 Toll Free Fax (877) SERV099 www.electromate.com sales@electromate.com 7

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Movement Generation Bipolar Principle • motor coils are bipolar • every coil end will be positive (”+”) or ground (”-”) PhA1 PhA2 GND + N S Sold & Serviced By: ELECTROMATE Toll Free Phone (877) SERVO98 Toll Free Fax (877) SERV099 www.electromate.com sales@electromate.com 8

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Movement Generation Unipolar Drive • low side switches • 4 switches for the whole motor + I GND Sold & Serviced By: ELECTROMATE Toll Free Phone (877) SERVO98 Toll Free Fax (877) SERV099 www.electromate.com sales@electromate.com 9

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Movement Generation Bipolar Drive • switches in bridge configuration • 2 full bridges (or H-bridges) are needed = 8 switches + I GND Sold & Serviced By: ELECTROMATE Toll Free Phone (877) SERVO98 Toll Free Fax (877) SERV099 www.electromate.com sales@electromate.com 10

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Movement Generation Tin Can Motor Sold & Serviced By: ELECTROMATE Toll Free Phone (877) SERVO98 Toll Free Fax (877) SERV099 www.electromate.com sales@electromate.com 11

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Movement Generation Tin Can Motor - Step Generation front side teeth back side teeth S N if there is only 1 magnetic system... motor is able to start in both directions ) ) S direction is undefined Sold & Serviced By: ELECTROMATE Toll Free Phone (877) SERVO98 Toll Free Fax (877) SERV099 www.electromate.com sales@electromate.com 12

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Movement Generation Tin Can Motor Coil Stator Core Bobbin Shaft Permanent Magnet Sold & Serviced By: ELECTROMATE Toll Free Phone (877) SERVO98 Toll Free Fax (877) SERV099 www.electromate.com sales@electromate.com 13

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Movement Generation Tin Can Motor - Step Generation 2 magnetic systems = 2 stators... electrical phase shift 90 ° ) N direction is defined by coil control sequencing ) control pattern (bipolar motor): coil 1 coil 2 coil 1 coil 2 N stator 1 front side teeth back side teeth direction CCW direction CW By: st Sold & Serviced ELECTROMATE Toll Free Phone (877) SERVO98 Toll Free Fax (877) SERV099 www.electromate.com sales@electromate.com 14

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Movement Generation VR - Step Generation Old Technology, No Longer Used Sold & Serviced By: ELECTROMATE Toll Free Phone (877) SERVO98 Toll Free Fax (877) SERV099 www.electromate.com sales@electromate.com 15

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Movement Generation Hybrid - Step Generation Flame B.B. Stator P.M. Bobbin Coil Rotor Bracket Stator Teeth Coil Shaft P.M. Rotor Sold & Serviced By: ELECTROMATE Toll Free Phone (877) SERVO98 Toll Free Fax (877) SERV099 www.electromate.com sales@electromate.com 16

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Movement Generation Step Loss S S N N S N § Rotor follows the stator field § Rotor reaches the end stop Î noise § Rotor is not able to follow the stator field § Rotor swings back § Motor will always loose n·4 steps Sold & Serviced By: ELECTROMATE Toll Free Phone (877) SERVO98 Toll Free Fax (877) SERV099 www.electromate.com sales@electromate.com 17

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Stepper and Synchronous Motors • Movement Generation • Step Mode • Torque Generation • Characteristics • Reduced Duty Cycle • Synchronous Motor Sold & Serviced By: ELECTROMATE Toll Free Phone (877) SERVO98 Toll Free Fax (877) SERV099 www.electromate.com sales@electromate.com 19

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Step Mode Full Step Mode • Step angle = catalogue value S N S S N I 1 / I 1max N I 2 / I 2max 1 0 -1 1 0 -1 coil current in a bipolar motor Sold & Serviced By: ELECTROMATE Toll Free Phone (877) SERVO98 Toll Free Fax (877) SERV099 www.electromate.com sales@electromate.com 20

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Step Mode Half Step Mode • Step angle = half catalogue value S N S N I 1 / I 1max 1 0 -1 I 2 / I 2max 1 0 -1 coil current in a bipolar motor Sold & Serviced By: ELECTROMATE Toll Free Phone (877) SERVO98 Toll Free Fax (877) SERV099 www.electromate.com sales@electromate.com 21

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Step Mode Half Step vs. Compensated Half Step 1 0 -1 1 0 -1 1 1/ √ 2 0 -1/ √ 2 -1 1 1/ √ 2 0 -1/ √ 2 -1 I 1 / I 1max I 2 / I 2max I 1 / I 1max I 2 / I 2max Sold & Serviced By: ELECTROMATE Toll Free Phone (877) SERVO98 Toll Free Fax (877) SERV099 www.electromate.com sales@electromate.com 22

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Torque Generation Torque vs. Angle M el (torque) M H (holding torque) -2 -1 N N 1 2 -M H N 3 4 α α S N Sold & Serviced By: ELECTROMATE Toll Free Phone (877) SERVO98 N N Toll Free Fax (877) SERV099 www.electromate.com sales@electromate.com 24

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Torque Generation Positioning Accurancy M el (torque) Friction α 2 Δα α S Δα ...Step Angle Tolerance Sold & Serviced By: Accuracy depends on friction and motor tolerances (5-7% of step angle). ELECTROMATE Toll Free Phone (877) SERVO98 Toll Free Fax (877) SERV099 Tolerance exists at every position, but it will not sum up! www.electromate.com sales@electromate.com 25

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Torque Generation Micro Step Modus • Current in coils increases/decreases in small increments • with tin can motor: • micro step only for smoother travel at low frequencies M (torque) friction step no. 1 2 3 4 5 6 α Sold & Serviced By: ELECTROMATE Toll Free Phone (877) SERVO98 Toll Free Fax (877) SERV099 www.electromate.com sales@electromate.com 26

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Characteristics Torque Resonances may influence application! reduced duty cycle = increased power consumption (pull out graph) with chopper pull-in pull-out (pull out graph) Sold & Serviced By: f 1 f A f 2 f B frequency ELECTROMATE Toll Free Phone (877) SERVO98 Toll Free Fax (877) SERV099 www.electromate.com sales@electromate.com 28

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Characteristics Influence of Inertia J LOAD + J ROTOR Inertia Factor FI = f J ROTOR ) Load inertia reduces start-stop-range. Sold & Serviced By: ELECTROMATE Toll Free Phone (877) SERVO98 Toll Free Fax (877) SERV099 f www.electromate.com sales@electromate.com 29

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Characteristics Output Power Motor output power : P = M · ω ⋅ Π⋅ f with ω =2 z M...torque ω ...angular velocity f ...step frequency z ...steps per revolution Sold & Serviced By: ELECTROMATE frequency Toll Free Phone (877) SERVO98 Toll Free Fax (877) SERV099 www.electromate.com sales@electromate.com 30

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Characteristics Resonance • Step motor resonant because in short the rs behave much like a classi ss on a spring ”. Sold & Serviced By: ELECTROMATE Toll Free Phone (877) SERVO98 Toll Free Fax (877) SERV099 www.electromate.com sales@electromate.com 31

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Characteristics Resonance • When reacts same w change motor takes a step, the rotor changing stator field in the mass on a spring reacts to a sition. Sold & Serviced By: ELECTROMATE Toll Free Phone (877) SERVO98 Toll Free Fax (877) SERV099 www.electromate.com sales@electromate.com 32

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Characteristics Resonance - Just like the mass on a spring, the motion of the rotor settles into position after each step. - This settling can last as long as a second or more in worst cases! Sold & Serviced By: ELECTROMATE Toll Free Phone (877) SERVO98 Toll Free Fax (877) SERV099 www.electromate.com sales@electromate.com 33

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Characteristics Resonance - If the settling doesn ’t occur rapidly, or the ringing of the rotor gets worse, the motor can become unstable and lose position (stall). Sold & Serviced By: ELECTROMATE Toll Free Phone (877) SERVO98 Toll Free Fax (877) SERV099 www.electromate.com sales@electromate.com 34

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Characteristics Resonance • There are two major, negative side effects of resonance. - Rough motion • When step motors resonate they generally vibrate excessively. • This can be bad for sensitive equipment. - Loss of torque, which can lead to loss of position • When step motors resonate much of the torque available in the motor is used up in keeping the rotor synchronized with the stator field, and in worst cases the motor will not have enough torque to move the load. • Loss of torque often leads to stalling. Sold & Serviced By: ELECTROMATE Toll Free Phone (877) SERVO98 Toll Free Fax (877) SERV099 www.electromate.com sales@electromate.com 35

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Reduced Duty Cycle “We need more torque!“ Ö You need more output power. P = M · ω · [Nm · rad/s] • higher output power requires higher input power • -> power losses increase • -> duty cycle needs to be reduced, otherwise motor becomes too hot ) • Order a Motor with reduced duty cycle, • specify cycle time, • do not only request reduced coil resistance. • Otherwise you get a motor with reduced coil resistance. But the winding is changed so that it will have the same maximum power dissipation, same duty cycle and therefore the same outpu Sold & Serviced By: que. M...torque ω ...angular velocity = ELECTROMATE step _ frequency ⋅ 2 π Toll Free Phone (877) SERVO98 Toll Free Fax (877) SERV099 www.electromate.com steps _ per _ revolution sales@electromate.com 37

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Reduced Duty Cycle Independence from Resistance M Θ copper volume torque d ϕ = d α V Cu = A ⋅ l cu m = const. temperature ϑ ~P coil winding area A Cu Cu ϕ= Θ= n ⋅ I = S ⋅ A Cu 2 2 l average length of a R M S ⋅ A ϕ= Cu = P Cu S ⋅ V Cu = I ⋅ R~S ⋅ V Cu m ϕ α copper wire magnetic flux angle R M R ⋅ l M m ϕ≠ f(n,R) ϕ ~S P Cu ~S Θ 2 R M n I S current linkage magnetic resistance no. turns (winding) current current density Temperature ~ P Cu ~ S 2 P Cu consumed energy ϑ temperature Sold & Serviced By: For same duty cycle same current density is needed. ELECTROMATE Toll Free Phone (877) SERVO98 P Cu =const. ϑ =const. Duty Cycle=const. S is the parameter, not R! Toll Free Fax (877) SERV099 www.electromate.com sales@electromate.com 38

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Reduced Duty Cycle Operations T Δϑ max T Δϑ max t t continuous operation t operation with reduced duty cycle S t t B ...ON-time B T t S ...cycle time Δϑ max Duty Cycle t B ED = ⋅ 100% t B t S t t S Sold & Serviced By: ELECTROMATE Toll Free Phone (877) SERVO98 Toll Free Fax (877) SERV099 www.electromate.com • Duty cycle is based on 5 minutes cycle time (unless otherwise specified). sales@electromate.com 39

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Reduced Duty Cycle A Simplified Calculation input power at 100% duty cycle: P ED 100 = real duty cycle: U k R 2 U K ...supply voltage from catalogue R ph ..coil resistance ph 2 P ED 100 ⎛ U k ⎞ R ph ED = •100% = ⎜ ⎟ •100% = •100% P ⎝ U S ⎠ R ED 100 P ED100 ... Power for 100% duty cycle U S ... supply voltage in application R ED100 ... coil resistance for 100% duty cycle Sold & Serviced By: ELECTROMATE Toll Free Phone (877) SERVO98 Toll Free Fax (877) SERV099 www.electromate.com sales@electromate.com 40

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Synchronous Motor Schematic • construction is similar to bipolar stepper motor • electrical phase shift is done by capacitor instead • stepper motors are used with DC • synchronous motors are used with AC Parallel Connection Common, full voltage over both coils U~ Serial Connection U~ otherwise too many windings with & Serviced By: too thin wire -> not possib Sold ELECTROMATE Toll Free Phone (877) SERVO98 Toll Free Fax (877) SERV099 www.electromate.com sales@electromate.com 42

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Synchronous Motor Frequencies f = step frequency = f s t i 1 i 2 i 1 i 2 t bipolar stepper motor f = 200Hz t Speed is equal ! t synchronous motor f = 50Hz t f = frequency of coil current = f i Sold & Serviced By: ELECTROMATE Toll Free Phone (877) SERVO98 Toll Free Fax (877) SERV099 • f s = 4·f i (for motors with identical construction) www.electromate.com sales@electromate.com 43

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Synchronous Motor Operation Area C C N ±10% operation area minimum capacity U N ±10% U Sold & Serviced By: ELECTROMATE Toll Free Phone (877) SERVO98 Toll Free Fax (877) SERV099 www.electromate.com sales@electromate.com 44

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Competitors for Stepper Motor Rotary: Portescap (Danaher) HSI (Haydon Switch & Instrument) Hybrid: Lin Engineering Portescap (Danaher) Oriental Motor Sanyo Denki, Shinano Linear: HSI (Haydon Switch & Instrument) Lin Engineering Sold & Serviced By: ELECTROMATE Toll Free Phone (877) SERVO98 Toll Free Fax (877) SERV099 www.electromate.com sales@electromate.com 45

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NPM/NPA Products • Tin-Can Rotary <PF/PFC Series> PF20, PF25, PF25C, PF35, PF35T, PF42, PF42T, PF42H PF55, PF55H • Tin-Can Linear: <PFL/PFCL Series> PFCL25, PFL35T • Hybrid: <PJB Series> PJB42S, PJB56H <PR Series> ( Only for North America ) PR20, PR28, PR35, PR42, PR57 Sold & Serviced By: ELECTROMATE Toll Free Phone (877) SERVO98 Toll Free Fax (877) SERV099 www.electromate.com sales@electromate.com 46

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Designation - PF/PF Series • PF C 42 H - 48 C 1 Connector Version Motor Size Dia. (mm) 25, 35, 42, 55 Motor Length or High Torque Version Blank: Standard T: Thin stack (Avail. In 35 and 42) H: High Torque (Avail. 42 and 55) Magnet Material 1: Ferrite Anisotropic 2: Ferrite Isotropic 4: Neodymium Winding Code Unipolar> B:24V, C:12V, D:5V Bipolar> P:12V, Q:5V Step/Rev 24: 15deg/step 48: 7.5deg/step 96: 3.75deg/step Sold & Serviced By: ELECTROMATE Toll Free Phone (877) SERVO98 Toll Free Fax (877) SERV099 www.electromate.com sales@electromate.com 47

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Designation - PF/PF Series • PFC42H-48C1 G 1/10 Gear Ratio G: w/ gear head Sold & Serviced By: ELECTROMATE Toll Free Phone (877) SERVO98 Toll Free Fax (877) SERV099 www.electromate.com sales@electromate.com 48

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Designation - PR Series • PR 42 H -25 - 04 04 J A Size (mm) H: High Torque S: Standard Stack Length (mm) Motor Current 04: 0.4Amp/phase 10:1.0Amp/phase A: Shingle Shaft B: Double Shaft Step Angle J: 1.8deg/step (=200step/rev) M:0.9deg/step (=400step/step) Step/Rev 24: 15deg/step 48: 7.5deg/step 96: 3.75deg/step Sold & Serviced By: ELECTROMATE Toll Free Phone (877) SERVO98 Toll Free Fax (877) SERV099 www.electromate.com sales@electromate.com 49

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Weakness and Settlements Mis-step -> 1. Taking Care Margin (Chose Best) 2. Closed loop (Add Encoder) 3. Use/Change Higher Current Resonance -> 1. Use High Resolution Motor 2. Use Microstep Driver 3. Adjustment (reduce) Current Sold & Serviced By: ELECTROMATE Toll Free Phone (877) SERVO98 Toll Free Fax (877) SERV099 www.electromate.com sales@electromate.com 50

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Stepper VS Servo (Brushless) Stepper Servo Cost √ Speed (600rpm) √ (3000rpm) Power/Torque √ Response √ Silence √ Easy to Use √ Sold & Serviced By: ELECTROMATE Toll Free Phone (877) SERVO98 Toll Free Fax (877) SERV099 www.electromate.com sales@electromate.com 51

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Glossary -1 Holding Torque The holding torque is the maximum torque the stepping motor has when rated current is being supplied but the motor is not rotating (with consideration given to the permissible strength of the gear when applicable). If you are setting "automatic current down (Idle Current)" function at motor standstill, the holding torque should be less than setting rated current. Pullout Torque Pullout torque is the maximum torque that can be output at given speed. When selecting a motor, be sure the required torque falls within this curve. Rotor Inertia This refers to the inertia of rotor inside the motor. This is necessary when the required torque (acceleration torq Sold & Serviced By: for the motor needs is calculated. ELECTROMATE Toll Free Phone (877) SERVO98 Toll Free Fax (877) SERV099 www.electromate.com sales@electromate.com 52

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Glossary -2 Rated Current The rated current is determined by motor temperature rise. It is the current value that can flow to the motor coils continuously at motor standstill. As a general rule, the current must be set to the rated current. Step Angle The step angle is the angular distance (in degrees) that the motor moves at the input of one pulse from the driver. It differs depending on the motor structure and excitation system. Gear Ratio This is the ratio in rotation speed between the input speed from the motor and the speed of the ear output shaft. For example, the gear ratio 10:1 is that when the input speed from the motor is 10rpm, the gear output shaft is 1rpm. Sold & Serviced By: ELECTROMATE Toll Free Phone (877) SERVO98 Toll Free Fax (877) SERV099 www.electromate.com sales@electromate.com 53

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Glossary -3 Allowable (Permissible) Torque The allowable torque represents the torque value limited by the mechanical strength of the gear. Backlash The play of gear output shaft when the motor shaft is fixed. When positioning in bi-direction, the positioning accuracy is affected. Maximum Starting Frequency (fs) This is the maximum pulse speed at which the motor can start or stop instantly (without an acceleration or deceleration period) when the functional load and inertial load of the stepper motor Serviced By: are 0. Driving the motor at greater than this pulse spee Sold & requires gradual acceleration or deceleration. This frequency ELECTROMATE drops when there is load inertia on the motor. Toll Free Phone (877) SERVO98 Toll Free Fax (877) SERV099 www.electromate.com sales@electromate.com 54

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Glossary -4 Torque Pull-Output Torque Holding Torque Pull-in Torque Max. Starting Frequency Spee Sold & Serviced By: ELECTROMATE Toll Free Phone (877) SERVO98 Toll Free Fax (877) SERV099 www.electromate.com sales@electromate.com 55