Review of How Motor Works August 2000 Review of How Motor Works Motor converts Electrical Energy to Rotating Mechanical Energy Coils placement in motor creates rotating, magnetic field in stator Rotating magnetic field cuts rotor bar and induces current in rotor Rotor current creates magnetic field on rotor Attraction of rotor to stator creates torque and, hence, horsepower

AC Motor Review In an AC Motor, speed varies by: Motor Speed (rpm) = 120 x Frequency - Slip # of Poles Since you can not change the number of poles in an AC motor, the frequency is changed to vary the speed.

Varying the Speed of an AC Motor 1800 (rpm) 1800 = 60 x 120 (rpm) 4 900 (rpm) 900 = 30 x 120 (rpm) 4 30 Hz 60 Hz

AC Motor Review In an AC motor, Torque Varies by: August 2000 AC Motor Review In an AC motor, Torque Varies by: T = K x ( )2 x I Line E F Where: K is a constant E is applied voltage F is input frequency I Line is motor current Torque in an AC motor is calculated using a constant, the volts over the frequency squared, and the line current. If you are running at a fixed speed and K is a constant, the Torque is directly proportional to the motor current. As it increases and decreases so does the torque.

Torque/Current Relationship What you really need to know…... AC Motor Review Torque/Current Relationship What you really need to know…... Current is roughly proportional to load torque The higher the load torque the higher the current

Horsepower of an AC motor can be determined by: AC Motor Review Horsepower of an AC motor can be determined by: HP = Torque x Speed 5252 Where: Torque is in lb-ft Speed is in RPM 5252 is a constant

Motor nameplate Horsepower is achieved at Base RPM: HP = Torque * Speed / 5252 Constant Torque Range Constant Horsepower Range Torque RPM Base Speed 100% Horsepower Note that motor nameplate horsepower is only achieved at and above base speed, NOT BEFORE.

Operation Above Base Speed August 2000 Operation Above Base Speed Sure! if we maintain voltage and increase resistance, the current will begin to drop. We are now in the constant voltage mode of operation, and Torque begins to fall off. HP

AC Motor Review IMPEDANCE IMPEDANCE: Resistance of AC Current flowing through the windings of an AC Motor NOTE: Impedance decreases as frequency decreases

Volts/Hertz Relationship I = V Z I = Current V = Voltage Z = Impedance To reduce motor speed effectively: Maintain constant relationship between current & torque A constant relationship between voltage and frequency must be maintained

Volt/Hertz Relationship The AC variable speed drive controls voltage & frequency simultaneously to maintain constant volts-per-hertz relationship keeping current flow constant. 230 V 30 Hz 60 Hz

AC Drive M Inverter - Changes fixed DC to adjustable AC August 2000 AC Drive Rectifier DC Bus Inverter AC Power Supply M Rectifier - Converts AC line voltage to Pulsating DC voltage Inverter - Changes fixed DC to adjustable AC - Alters the Frequency of PWM waveform Intermediate Circuit (DC BUS) - Filters the pulsating DC to fixed DC voltage

Sine Weighted PWM August 2000 Bus Voltage Level The Sine weighted PWM voltage output to the motor looks like this. The frequency of the switch from positive to negative is determined by the drive based on the speed reference input, and the RMS or Average voltage value for that frequency is determined by the number and width of the pulses. If I vary or "Modulate" the pulse width, I vary the RMS Voltage to the motor.

Sine Weighted PWM August 2000 That voltage creates a current waveform in the motor that is very nearly a sine wave; certainly much closer to a true sine wave than the other technologies used in AC Drives. Here are the PWM waveforms. So by modulating or changing the Width of the voltage pulses and the frequency that those pulses create we create a very close approximation of a sinusoidal current waveform. The near sinusoidal nature of the current accomplishes two of our four goals; minimizing the low order harmonics ‑ you can see that the spikes are much smaller than in other technologies‑ and maximizing the transfer of power in the fundamental frequency.

PWM waveform is a series of repetitive voltage pulses 1 3 + DC Bus - DC Bus VLL @ Drive 500 Volts / Div. Phase Current 10 Amps / Div. M2.00s Ch1 1.18V PWM waveform is a series of repetitive voltage pulses

Drive and Motor Compatibility August 2000 Drive and Motor Compatibility Voltage Wave @Drive Output V LL @ Drive 500 Volts / Div. @ Motor Potentially Damaging Voltage Peaks Voltage Wave @ Motor Conduit Box Scope traces from a 10 HP, 460 VAC VFD with 500 feet of cable between the VFD and the motor. The top wave shows the frequency at the drive output terminals. The bottom wave is the same wave at the motor terminals. An effect, called reflected wave, has raised the peak voltage at the motor terminals. 33

How to Specify -- NEMA Standards MG1-1993, Part 31.40.4.2 August 2000 How to Specify -- NEMA Standards MG1-1993, Part 31.40.4.2 Maximum of 1600 Volt Peaks At a minimum, variable-speed AC moors should meet NEMA MG1 Part 31.40.4.2 standards. That standard is depicted here. They should also have a minimum CIV rating of 1,600 V at rated operating temperature for 460 VAC applications and should have a higher voltage rating for 575 VAC applications. Always follow the lead length recommendations of the VFD manufacturer. Most have done extended testing to understand the reflected wave voltage amplitudes and dv/dt created by their products. Use reactors and filters when the distance between the drive and the motor exceeds the manufacturers recommendations. Use power-matched motor/drive packages that have been tested for compatibility in a wide range of operating conditions. Minimum Rise Time of .1 Microseconds

GV3000/SE V/Hz Operation Output Frequency Base Frequency 60 Output Voltage Hz 30 460 230 115 15 90 Ratio @ 460VAC = 7.67 V/Hz At Base RPM or 60Hz, the Motor sees line input voltage

GV3000/SE V/Hz Operation Output Frequency Base Frequency 60 Output Voltage Hz 30 460 230 115 15 90 Ratio @ 460VAC = 7.67 V/Hz At 25% of Base RPM or 15 Hz, Voltage & Frequency is 25%

VECTOR DRIVE Vector calculates Torque-Producing Current by Current (23.5 Amps) Magnetizing Current (8.5 Amps) 25.0 Amps Full Load Vector calculates Torque-Producing Current by knowing actual amps and magnetizing current.

GV3000/SE Vector Control - Torque can be produced, as well as regulated even at “0” RPM Motor Current is the VECTOR SUM of Magnetizing & Torque Current, this is where the term VECTOR DRIVE is derived Torque Current Magnetizing Current 100% Motor Current 90 Torque Current Magnetizing Current 10% Motor Current 90 Motor Current is the Vector Sum of Torque & Magnetizing

GV3000/SE Flux Vector Drive - simple diagram review August 2000 GV3000/SE Flux Vector Drive - simple diagram review A Vector Drive always regulates current “LEM” Current Sensors L1 L2 L3 Motor E Micro P Encoder feedback provides rotor speed & position information for calculations

( FVC + Speed Estimator ) August 2000 GV3000/SE Sensorless Vector Control - simple diagram review SVC estimates rotor speed & position to the stator field “LEM” Current Sensors L1 Motor L2 L3 Micro P ( FVC + Speed Estimator ) A “Speed Estimator” calculates rotor speed & position to maintain 90° to the field

Sensorless Vector Flux Vector 150% Overload 150% Overload August 2000 Sensorless Vector Flux Vector 150% Overload Operation to 0 RPM 120:1 Speed Range Speed Regulation 40:1, 0.5% Steady State 20:1, 1.0% Dynamic Dynamic Response 100+ radian Speed Loop 1000 radian Torque Loop Tunable Speed PI gains 150% Overload Operation @ 0 RPM 1000:1 Speed Range Speed Regulation 100:1, 0.01% Steady State 100:1, 0.5% Dynamic Dynamic Response 100+ radian Speed Loop 1000 radian Torque Loop Tunable Speed & Torque PI gains

AC Drives regulate Motor Speed based on designed slip INVERTER DUTY MOTORS NEMA Design ‘B” Motor w/ 3% Slip - Across the Line Start BDT 200% Operating Region on AC Drives LRT PUT FLT 100% Slip Base RPM AC Drives regulate Motor Speed based on designed slip

INVERTER DUTY MOTORS Blowers may be added to motors to allow operation at low speed including “0” RPM with 100% Torque continuous Some motor frames are sized so that just the surface area is suitable to dissipate motor heat w/o the need of a fan or blower

GV3000/SE with “Inverter & Vector Duty” AC Motors August 2000 GV3000/SE with “Inverter & Vector Duty” AC Motors VXS Motors Based on Reliance XEX Motor Designs TENV, TEFC-XT and TEBC Enclosures Ideal for; Positive Displacement Pumps and Blowers Extruders and Mixers Steel and Converting Process lines Standard Features; Encoder Mounting Provisions Motor Shaft Tapped for Stub @ ODE Accessory Face @ ODE Motor Winding Thermostats, 1/Phase 10:1 to 1000:1 CT speed ranges w/o derating Optional Motor review slide

GV3000/SE with “Inverter & Vector Duty” AC Motors August 2000 GV3000/SE with “Inverter & Vector Duty” AC Motors RPM-AC Motors Laminated Steel, DC-style construction DPFV, TENV, & TEBC enclosures Ideal for; Extruder applications Web processing & mill applications Retrofitting existing DC Drive & Motor systems Standard Features; High torque to inertia ratios Encoder Mounting Provisions Motor Winding Thermostats, 1/Phase Infinite CT speed range, 0 RPM continuous CHp Range of 2:1 on TENV & TEBC Frames Base Speeds from 650 RPM to 3600 RPM Optional Motor review slide

Speed Range Speed Range - Designed operating range of an inverter duty motor Example 1800 rpm motor 10:1 Speed Range = 180 -1800 (rpm)

CONSTANT TORQUE REGION Speed / Torque Curve of an AC Drive & Inverter Duty Motor % TORQUE 10 20 30 40 50 60 70 80 90 100 6 12 18 24 36 42 48 54 66 72 78 84 Torque HZ Acceptable Region for Continuous Operation Inverter Duty Motors operate at 1/4th Base RPM

CHp Operation above Base RPM is typically limited to 150% CONSTANT HP REGION Speed / Torque Curve of an AC Drive & Inverter Duty Motor 100 Torque 90 % TORQUE 80 Torque 70 60 Torque above base RPM = 100% % Base RPM 50 40 30 20 10 6 12 18 24 30 36 42 48 54 60 66 72 78 84 90 HZ CHp Operation above Base RPM is typically limited to 150%

CONSTANT TORQUE REGION Speed / Torque Curve of a Vector Drive & Vector Duty Motor % TORQUE 10 20 30 40 50 60 70 80 90 100 6 12 18 24 36 42 48 54 66 72 78 84 Torque HZ Acceptable Region for Continuous Operation Vector Duty Motors operate at “0” RPM w/ 100% Torque Cont.

Vector Duty Motors may have depending on their design CONSTANT HP REGION Speed / Torque Curve of a Vector Drive & Vector Duty Motor HZ % TORQUE 6 12 18 24 30 36 42 48 54 60 66 72 78 84 90 Torque 10 20 40 50 70 80 100 96 102 108 114 120 Vector Duty Motors may have CHP Ranges of 2 * Base Speed or more depending on their design Special motor & drive designs can allow operation up to 8 * Base RPM Some Vector Duty Motors can provide CHp ( 2 * Base RPM )

Drive Terminology V/Hz DC Boost Accel / Decel Frequency Voltage HP August 2000 Drive Terminology V/Hz DC Boost Accel / Decel Frequency Voltage HP Speed Skip & Bandwith Braking DB Regen Injection Coast Ramp Restart Preset Jog Current Limit Analog / Digital Power Factor Harmonics Ride - Thru Speed Range Speed Regulation Frequency Regulation Cogging Efficiency

Accel/Decel Acceleration Rate - Deceleration Rate Rate of change of motor speed. TIME Frequency 100 % 30 sec Example: 0 Speed - 1750 rpm  30 seconds

Full Voltage Bypass Drive Branch Fusing Bypass Disconnect Switch GV3000/SE M Input Disconnect Switch Bypass Option

Speed Regulation How Much Will the Speed Change August 2000 Speed Regulation How Much Will the Speed Change Between No Load and Full Load? Expressed as a Percentage Speed Regulation, as a Percentage, is how much the speed will change between no load (Minimal slip) and Full Load (Maximum Slip).

Speed Regulation August 2000 Here's a curve for a standard Induction motor. 3% drop in speed. But a standard DC Drive typically has a 1‑2% speed Regulation, and, out of the box, a motion control drive provides .1% speed regulation. Why the difference?

August 2000 The difference is that most DC drives and all Motion Control Drives are what's known as closed loop. That means that some sort of feedback device attached to the motor feed speed information back to the drive for use in correcting any speed discrepancies. Open loop, like most AC Drives, means no such feedback exists, and the drive assumes that what it told the motor to do is actually being done.

DC Voltage Boost August 2000 That's where DC Boost comes in. In order to drop enough voltage across the inductance, we raise or boost the output voltage above what it would be normally, until there is enough voltage across the inductance to provide the necessary torque to turn the motor or "Break" the motor away. Once that voltage boost reaches the level that it would have been on the standard curve, the boost is turned off and operation proceeds as normal. We accomplish DC Boost by widening the pulses in the PWM waveform, creating a higher average voltage, and therefore more current.

Unable to perform like DC, the industry looks to Vector Control Voltage Boost Voltage Boost over prolonged operating periods may result in overheating of the motor’s insulation system and result in premature failure. CAUTION: Motor Insulation Life is decreased by 50% for every 10°C above the insulation’s temperature capacity Unable to perform like DC, the industry looks to Vector Control

Critical Frequency An Output Frequency of a Controller that Produces a Load Speed at Which Severe Vibration Occurs. A Frequency at which Continuous Operation is Undesirable

Skip Bandwith

AC Drive Inputs Analog Inputs: Digital Inputs: 0-10 VDC ± 10 VDC 4-20 mA Digital Inputs: Start Stop Reset Forward/Reverse Run/Jog Preset Speeds

Trip Free Deceleration when enabled GV3000/SE High Bus Avoidance ( SVC & FVC ) For Trip Free Deceleration if low to medium inertia loads SPEED TIME Trip Free Deceleration when enabled

Snubber/Dynamic Braking Rectifier DC Bus Inverter AC Power Supply M Snubber/Dynamic Braking - Addition of Snubber Resitor Kit 7th IGBT - Dissipates excess energy to regulate braking - Regulator monitors DC bus voltage - Signal sent to 7th IGBT - Handles short term regenerative loads - Less expensive than AC line regeneratiion braking Braking Resistor

AC Regenerative Braking Drive 1 Drive 2 Drive 2 AC Power Supply AC Line Regeneration Module Severe Regenerative Braking - Addition of AC Line Regeneration Module - Drives powered through DC bus instead of through the Rectifier bridge - Share regenerative energy between motoring and regenerating drives - Send energy back to AC Line instead of dissipating as heat - Monitors DC bus voltage - Sends Excess voltage back to AC line - Handles long term regenerative loads - Run Multiple Drives off 1 Module

Auto - Restart How will the drive react after being shut down by a fault condition? Will the drive resume Running after the Fault condition is Cleared? (Sometime restricted to certain Faults)

Preset Speeds A Pre-Programmed Command Frequency That can be activated via Mode Select or Input Device

Current Limit The ability of a drive to react to the increased current caused by momentarily increasing the load on the motor (Shock Loading) without tripping the drive on Overcurrent.

Power Loss Ride-Through The Ability of a Controller to sustain itself through a loss of Input Line Voltage for a specific period of time.

Operating Range For Variable Frequency AC Drives August 2000 Operating Range For Variable Frequency AC Drives Now that we understand the technology of AC drives, we need to apply what we know to the characteristics we already know about the AC Motor. Only then can we know how the two will react together. Here is our standard speed torque curve for our NEMA B design motor. An AC Drive has a fixed Maximum Continuous Current limit which we have shown here as a dotted line representing 100% of drive current. In addition, most drives have an intermittent ability to supply current up to some additional level. We have chose the 150% level found in drives like the BUl 1336. Since the drive will be limiting the current available to the motor, we will no longer see the entire speed torque curve. We will not be able to get full breakdown torque from the motor and will not see 200% starting torque as we did across the line. Remember that 200% required 600% current. We are now limited to 150%. What we create then, is an operating range on the torque curve for a motor use with a drive. the area you see here is for full voltage at rated frequency. A motor controlled by an AC Drive will always operate somewhere in this range.