Hitachi Sj7002 Owners Manual
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Inverter Specifications Geting Started 1–10 General SpecificationsThe following table (continued on next page) applies to all SJ7002 inverter models. ItemGeneral Specifications Protective enclosure *1, *11 IP20 (NEMA 1); models -750xFU2 to -4000xFU2 is IP00 Control method Line-to-line sine wave pulse-width modulation (PWM) control Output frequency range *4 0.1 to 400 Hz Frequency accuracy Digital command: ± 0.01% of the maximum frequency Analog command: ± 0.2% (at 25 °C ± 10 °C) Frequency setting resolution Digital: ± 0.01 Hz; Analog: (max. frequency )/4000, [O] terminal: 12-bit 0 to 10V; [OI] terminal: 12-bit, 4-20mA; [O2] terminal: 12-bit –10 to +10V Volt./Freq. characteristic *5 V/F optionally variable (30 to 400Hz base frequency), V/F control (constant torque, reduced torque), sensorless vector control, 0-Hz-range sensorless vector control Speed fluctuation ± 0.5% (sensorless vector control or 0-Hz range sensorless vector control) Acceleration/deceleration time 0.01 to 3600 sec., (linear curve profiles, accel./decel. selection), two-stage accel./decel. Starting Torque *6 200% at 0.3 Hz (SLV or 0Hz-range SLV), 150% at 0 Hz-range SLV, with motor one frame size down) For -750Hxx to -1500Hxx: 180% at 0.3Hz 150% at 0 Hz range with feedback board (with 0Hz-range sensorless vector control or with motor one frame size down) For -750Hxx to -1500Hxx: 130% at 0.3Hz Carrier frequency range Models -004xFU2 to -550xFU2: 0.5 to 15.0 kHz; Models -750xFU2 to -1500xFU2: 0.5 to 10.0 kHz; Models -1850HFU2 to -4000HFU2: 0.5 to 3.0 kHz DC braking Performs at start under set frequency at declaration, via an external input (braking force, time, and operating frequency) Overload capacity (output current) 150% for 60 seconds, 200% (180% for 75kW / 100HP and larger) for 0.5 seconds Input signal Freq. setting Operator keypad Up and Down keys / Value settings Potentiometer Analog se tting via potentiometer on operator keypad External signal *8 0 to 10 VDC and –10 to +10 VDC (input impedance 10k Ohms), 4 to 20 mA (input impedance 250 Ohms), Potentiometer (1k to 2k Ohms, 2W) Serial port RS485 interface FW/RV Run Operator panel Run key / Stop key (change FW/RV by function command) External signal FW Run/Stop (NO contact), RV set by terminal assignment (NC/NO), 3-wire input available Serial port RS485 interface Intelligent Input terminals (assign eight functions to terminals) RV (reverse run/stop), CF1~CF 4 (multi-speed select), JG (jogging), DB (external DC braking), SET (set 2nd motor data), 2CH (2 -stage accel./decel.), FRS (free-run stop), EXT (external trip), USP (unattended start protection), CS (commercial power source), SFT (software lock), AT (analog input voltage/current select), SET3 (set 3rd motor data), RS (reset inverter), STA (start, 3-wire interface), STP (stop, 3-wire interface), F/R (FW/RV 3-wire interface), PID (PID ON/OFF), PIDC (PID reset), CAS (control gain setting), UP (remote co ntrol Up function, motorized speed pot.), DWN (remote control Down function, motorized speed pot .), UDC (remote control data clearing), OPE (Operator control), SF1- SF7 (Multispeed bits 0-7), OLR (Overload limit change), TL (torque limit enable), TRQ1 (torque limit se lection bit 1, LSB), TRQ2 (torque limit selection bit 2, MSB), PPI (Proportional / Proportional/Integral mode selection), BOK (Brake confirmation signal), ORT (Orien tation – home search), LAC (LAC: LAD cancel), PCLR (Position deviation reset), STAT (pulse train position command input enable), ADD (trigger for frequency addition), F-TM (fo rcible-terminal operation), ATR (permission of torque commend input), KHC (cumulative power clearance), SON (servo ON), FOC (pre-excita tion), MI1 (general-purpose input 1), MI2 (general- purpose input 2), MI3 (general-purpose input 3), MI4 (general-purpose input 4), MI5 (general-purpose input 5), MI6 (general-purpose input 6), MI7 (general-purpose input 7), MI8 (general-purpose input 8), AHD (analog command holding), NO (not selected) Thermistor input One terminal (PTC characteristics) Phone: 800.894.0412
SJ7002 Inverter Getting Started 1–11 Output signalIntelligent Outp ut terminals (assign six functions to five open collector outputs and one relay NO-NC contact) RUN (run signal), FA1 (Frequency arrival type 1 – constant speed), FA2 (Frequency arrival type 2 – over-frequency), OL (overl oad advance notice signal 1), OD (Output deviation for PID control), AL (alarm signal), FA3 (Frequency arrival type 3 – at- frequency), OTQ (over-torque signal), IP (Instantaneous power failure signal), UV (Under-voltage signal), TRQ (In torque limit), RNT (Run time over), ONT (Power-ON time over), THM (thermal alarm), BRK (Brake release signal), BER (Brake error signal), ZS (Zero speed detect), DSE (speed deviation maximum), POK (Positioning completion), FA4 (Frequency arrival type 4 – over-frequency 2), FA5 (Frequency arrival type 5 – at-frequency 2), OL2 (Overload notic e advance signal 2), FBV (PID feedback comparison), NDc (communication line disconne ction), LOG1 (logical operation result 1), LOG2 (logical operation result 2), LOG3 (logical operation result 3), LOG4 (logical operation result 4), LOG5 (logical operation result 5), LOG6 (logical operation result 6), WAC (capacitor life warning), WAF (coolin g fan speed drop), FR (starting contact signal), OHF (heat sink overheat warning) , LOC (low-current indication signal), MO1 (general-purpose output 1), MO2 (general-p urpose output 2), MO3 (general-purpose output 3), MO4 (general-purpose output 4), MO5 (general-purpose output 5), MO6 (general-purpose output 6), IRDY (inverte r ready), FWR (forward rotation signal), RVR (reverse rotation signal), MJA (major failure signal), Terminals 11-13 or 11-14 automat- ically configured as AC0-AC2 or AC0-AC3 per alarm code output selection Intelligent monitor output terminals Analog voltage monitor, anal og current monitor (8-bit reso lution), and PWM output, on terminals [AM], [AMI], [FM] Display monitor Output frequency, output current, moto r torque, scaled value of output frequency, trip history, I/O terminal condition, el ectrical power and other parameters Other user-settable parameters V/F free-s etting (up to 7 points), freq. upper/lower limit, freq. jump, accel/decel curve selection, manual torque bo ost value and freq. adjustment, energy saving operation, analog meter tuning, start fre quency, carrier frequency, electronic thermal protection level, external frequency outpu t zero/span reference, external frequency input bias start/ end, analog input selection, retry after trip, restart after instantaneous power failure, various signal outputs, reduced voltage star t, overload restriction, default value setting (US, Europe, Japan), automa tic deceleration at power failure, AVR function, fuzzy accel/decel, auto-tuning (on- line/off-line), high-torque multi-motor operation (sensor- less vector control of two motors by one inverter) Protective functions Over-current, overload, braking resistor overload, over voltage, EEPROM error, under- voltage error, CT (current transformer) error, CPU error, external trip, USP error, ground fault, input over voltage, instantaneous power failure, expansion card 1 error, expansion card 2 error, invert er thermal trip, phase failure detection, IGBT error, therm- istor error Environ- ment Temperature (*9) Operating (ambient): -10 to 50 °C / Storage: -20 to 65 °C Humidity 20 to 90% relative humidity (non-condensing) Vibration *10 Models SJ700–004xxx to 220xxx: 5.9 m/s 2 (0.6G), 10 to 55 Hz Models SJ700–300xx to 1500xxx: 2.94 m/s2 (0.3G), 10 to 55 Hz Models SJ700–3150xx to 4000xxx: 1.96 m/s2 (0.2G), 10 to 55 Hz Location Altitude 1,000 m or less, indoors (no corrosive gasses or dust) Coating color Gray Accessories Feedback expansion card SJ-FB (vector control loop speed sensor) Digital input exp. card SJ-DG (4-digit BCD / 16-bit binary) DeviceNet expansion card Option to support the open-network DeviceNet function LonWorks expansion card Option to support the open-network LonWorks function Profibus-DP option Option to support the open-network Profibus-DP function Other optional accessories EMI filter, AC reactor, DC reactor, radio noise filter, braking resistors, braking units, LCR filter, comm unication cables Operator input devices OPE–SRE (4-digit LED with potentiometer) / OPE–S (4-digit LED w/o potentiometer), Optional: OPE-SR (4-digit LED with potentiometer, Japanese/English overlay), SRW–0EX Multilingual operator with copy function (English, Spanish, French, German, Italian, and Portuguese) ItemGeneral Specifications Phone: 800.894.0412
Inverter Specifications Geting Started 1–12 Signal RatingsDetailed ratings are in “Specifications of Control and Logic Connections” on page 4–9. DCL Filter SpecificationsDirect reactor filters (DCL) are available for the Hitachi high-capacity SJ7002 inverters, models -1850HFU2 to -4000HFU2. The DCL specif ications are in the following table. Carrier Frequency DeratingThe maximum carrier frequency Fcthat provides full inverter rated output depends on the particular inverter model. However, you may op erate an inverter at the maximum settable F c with an output derating. Refer to the table below for the carrier frequency values and output deratings. Signal / ContactRatings Built-in power for inputs 24VDC supply, 100 mA maximum Intelligent (programmable) logi c inputs 27VDC maximum, 4.7kΩ input impedance Intelligent (programmable) logic outputs Ope n collector type, 50mA max. ON state current, 27 VDC maximum OFF state voltage Thermistor input Minimum thermistor power 100mW PWM output 0 to 10VDC, 1.2 mA max., 50% duty cycle Voltage analog output 0 to 10VDC, 2 mA max. Current analog output 4-20 mA, nominal load impedance 250Ω Analog input, current 4 to 19.6 mA range, 20 mA nominal Analog input, voltage unipolar 0 to 9.6 VDC range, 10VDC nominal, 12VDC max., input impedance 10 k Ω Analog input, voltage bipolar –9.6 to 9.6 VDC range, ±10VDC nominal, ±12VDC max., input impedance 10 k Ω +10V analog reference 10VDC nominal, 10 mA maximum Alarm relay, normally closed contacts Maximum loads: 250VAC, 2A; 30VDC, 8A resistive load 250VAC, 0.2A; 30VDC, 0.6A inductive load Minimum loads: 100 VAC, 10mA; 5VDC, 100mA Alarm relay, normally open contacts 250VAC, 1A; 30VDC 1A max. resistive load / 250VAC, 0.2A; 30VDC, 0.2A max. inductive load Min. loads: 100 VAC, 10mA; 5VDC, 100mA ItemDCL Specifications DCL models, DCL-H-xxx 185 315 400 Rated current (A) 515.0 680 1042 Insulation class Type H Weight kg / lb. 6575 90 200V Class Inverters Capacity (kW)Maximum F c (kHz)Derating at Fc = 15 kHzCapacity (kW)Maximum F c (kHz)Derating at Fc = 15 kHz 0.4 15 100% 15 12 95% (60.8A or less) 0.75 15 100% 18.5 10 90% (68.4A or less) 1.5 15 100% 22 7 70% (66.5A or less) 2.2 15 100%305 80% (96.8A or less) 3.7 / 4.0 15 100%37 10 75% (108.7A or less) 5.5 15 100%455 70% (127.4A or less) 7.5 15 100%555 70% (154.0A or less) 11 12 90% (41.4A or less) — — — Phone: 800.894.0412
SJ7002 Inverter Getting Started 1–13 NOTE: When replacing an SJ300 inverter combined with LCR filter, please check the type code of LCR filter and consult for compatibility (75 to132kW). 400V Class Inverters Capacity (kW)Maximum F c (kHz)Derating at Maximum FcCapacity (kW)Maximum F c (kHz)Derating at Maximum Fc 0.75 15 100% 37 8 80% (60.0A or less) 1.5 15 100% 45 9 75% (68.2A or less) 2.2 15 100% 55 6 60% (67.2A or less) 3.7 15 100% 75 6 85% (126.7A or less) 5.5 15 100%904 75% (132.0A or less) 7.5 15 100%110 6 70% (151.9A or less) 11 15 100%150 3 60% (156.0A or less) 15 14 95% (30.4A or less) 185 3 100% 18.5 10 90% (34.2A or less) 315 3 100% 22 6 75% (36.0A or less) 400 3 80% (640.0A or less) 30 10 75% (43.5A or less) — — — Phone: 800.894.0412 - Fax: 888.723.4773 - Web: www.clrwtr.com - Email: [email protected]
Introduction to Variable-Frequency Drives Geting Started 1–14 Introduction to Variable-Frequency Drives The Purpose of Motor Speed Control for IndustryHitachi inverters provide accurate speed control for 3-phase AC induction motors. You connect AC power to the inverter, and connect the inverter to the motor. Many applications can benefit from the use of variable-speed drives in several ways: Energy savings - HVAC Need to coordinate speed with an adjacent process - te xtiles and printing presses Need to control ac celeration and deceleration (torque) Sensitive loads - elevators, food processing, pharmaceuticals What is an Inverter?The term inverter and variable-fre quency drive are related and somewhat interchangeable. An electronic drive for an AC motor controls the motor’s speed by varying the frequency of the power sent to the motor. An inverter, in general, is a device that conv erts DC power to AC power. The figure below shows how the variable-frequency drive employs an internal inverter. The drive first converts incoming AC power to DC through a rectifier bri dge, creating an internal DC bus voltage. Then the inverter circuit converts the DC back to AC again to power the motor. The special inverter can vary its output frequency and voltage according to the desired motor speed. The simplified drawing of the inverter shows th ree double-throw switches. In Hitachi inverters, the switches are actually IGBTs (isolated ga te bipolar transistors). Using a commutation algorithm, the microprocessor in the drive sw itches the IGBTs ON and OFF at a very high speed to create the desired output waveforms. The inductance of the motor windings helps smooth out the pulses. Torque and Constant Volts/ Hertz OperationIn the past, AC variable speed drives used an open loop (scalar) technique to control speed. The constant-volts-per-hertz operation maintains a constant ratio between the applied voltage and the applied frequency. With these conditions, AC inductio n motors inherently delivered constant torq ue across the operating speed range. For some applications, this scalar technique was adequate. Today, with the advent of sophisticated micro- processors and digita l signal processors (DSPs), it is possible to control the speed and torque of AC inductio n motors with unprece- dented accuracy. The SJ700 2 utilizes these devices to perform complex mathematical calcula- tions required to achieve superior perfo rmance. The technique is referred to as sensorless vector control . It allows the drive to continuously mo nitor its output voltage and current, and their relationship to each other. From this it mathematically calculates two vector currents. One Power Input Inverter L1/R Motor L2/S L3/T Rectifier Variable-frequency Drive Internal DC Bus + + – U/T1 V/T2 W/T3 Converter Output frequency Output voltage 100% V 0 100%f Constant torque Phone: 800.894.0412
SJ7002 Inverter Getting Started 1–15 vector is related to motor flux current, and the other to motor torque current. The ability to separately control these two vect ors is what allows the SJ700 2 to deliver extraordinary low- speed performance and speed control accuracy. Inverter Input and Three-Phase PowerThe Hitachi SJ7002 Series of inverters includes two sub-groups: the 200V class and the 400V class inverters. The drives described in this manual may be used in either the United States or Europe, although the exact voltage level for comm ercial power may be slightly different from country to country. Accordingly, a 200V class inverter requires (nominal) 200 to 240VAC, and a 400V class inverter requires from 380 to 480VAC. All SJ700 2 inverters require three-phase input power, whether 200V or 400V class. TIP: If your application only has single phase po wer available, refer to the Hitachi SJ100 Series inverters. SJ100 inverters of 3HP or less can accept single phase input power. The common terminology for sing le phase power is Line (L) and Neutra l (N). Three-phase power connections are usually labe led Line 1 (L1), Line 2 (L2) and Line 3 (L3). In any case, the power source should include a ground connection. That ground conne ction will need to connect to the inverter chassis and to the motor frame (see “ Wire the Inverter Output to Motor” on page 2–26). Inverter Output to the MotorThe AC motor must be connected only to the inverter’s output terminals. The output terminals are uniquely labeled (to differentiate them from the input terminals) with the designations U/T 1, V/T2, and W/T3. This corresponds to typical moto r lead connection designa- tions T1, T2, and T3. It is of ten not necessary to connect a particular inverter output to a particular motor lead for a new application. The consequence of swapping any two of the three connections is the reversal of the motor direction. In applic ations where reversed rotation could cause equipment damage or pe rsonnel injury, be sure to verify direction of rotation before attempting full-speed operation. For safety to pers onnel, you must connect the motor chassis ground to the ground connection at the bottom of the inverter housing. Notice the three connections to the motor do no t include one marked “Neutral” or “Return.” The motor represents a balanced “Y” impedance to the inverter, so there is no need for a separate return. In other words, each of the three “Hot” connections serves also as a return for the other connections, because of their phase relationship. The Hitachi inverter is a rugged and reliable devi ce. The intention is for the inverter to assume the role of controlling power to the motor durin g all normal operations. Therefore, this manual instructs you not to switch OFF power to the inverter while the motor is running (unless it is an emergency stop). Also, do not install or use disc onnect switches in the wiring from the inverter to the motor (except thermal disconnect). Of cour se, safety-related devices such as fuses must be in the design to break power during a malf unction, as required by NEC and local codes.3-Phase AC Motor U/T1 V/T2 W/T3 Earth GND Phone: 800.894.0412 - Fax: 888.723.4773 - Web: www.clrwtr.com - Email: [email protected]
Introduction to Variable-Frequency Drives Geting Started 1–16 Intelligent Functions and ParametersMuch of this manual is devoted to describing how to use inverter functions and how to configure inverter parameters. The inverter is microproces- sor-controlled, and has many independent functions. The microprocessor has an on-board EEPROM for parameter storage. The inverter’s front panel keypad provides access to all functions and parameters , which you can access through other devices as well. The general name for all these devices is the digital operator, or digital operator panel . Chapter 2 will show you how to get a motor running, using a minimal set of function commands or configuring parameters. The optional read/write programmer will let you read and write inverter EEPROM contents from the programmer. This feature is particularly useful for OEMs who need to duplicate a particu- lar inverter’s settings in many other inverters in assembly-line fashion. BrakingIn general, braking is a force that attempts to slow or stop motor rotation. So it is associated with motor deceleration, but may also occur even when the load attempts to drive the motor faster than the desired speed (overhauling). If you need the motor and load to decelerate quicker than their natural de celeration during coasting, we recommend installing a braking resistor. The dynamic braking un it (built into certain SJ700 2 models) sends excess motor energy into a resistor to slow the motor and load (see “ Introduction” on page 5–2 and “ Dynamic Braking” on page 5–6 for more information). For loads that continuously overhaul the motor for extended periods of time, the SJ700 2 may not be suitable (contact your Hitachi distributor). The inverter parameters include acceleration and deceleration, which you can set to match the needs of the application. For a particular invert er, motor, and load, there will be a range of practically achievable acce lerations and decelerations. Velocity ProfilesThe SJ7002 inverter is capable of sophisti- cated speed control. A graphical representa- tion of that capability will help you understand and configure the associated parameters. This manual makes use of the velocity profile graph used in industry (shown at right). In the example, the acceler- ation is a ramp to a set speed, and the decel- eration is a decline to a stop. Fixed speed Accel Decel t Speed Velocity Profile Phone: 800.894.0412
SJ7002 Inverter Getting Started 1–17 Acceleration and deceleration settings specify the time required to go from a stop to maximum frequency (or visa versa). The resulting slope (speed change divided by time) is the acceleration or deceleration. An increase in output frequency uses the accel- eration slope, while a decrease uses the deceleration slope. The accel or decel time a particular speed cha nge depends on the starting and ending fre quencies. However, the slope is constant, corresponding to the full-scale accel or decel time setting. For example, the full-scale acceleration setting (time) may be 10 seconds—the time required to go from 0 to 60 Hz. The SJ700 2 inverter can store up to 16 preset speeds. And, it can apply separate accelera- tion and deceleration transitions from any preset to any other preset speed. A multi- speed profile (shown at right) uses two or more preset speeds, which you can select via intelligent input terminals. This external control can apply any preset speed at any time. Alternatively, the selected speed is infinitely variable across the speed range. You can use the potentiometer control on the keypad for manual control. The drive accepts analog 0-10V signals and 4-20 mA control signals as well. The inverter can drive the motor in either direction. Separate FW and RV commands select the direction of rotation. The motion profile example shows a forward motion followed by a reverse motion of shorter duration. The speed presets and analog signals control the magnitude of the speed, while the FW and RV commands determine the direction before the motion starts. NOTE: The SJ7002 can move loads in both directions. Ho wever, it is not designed for use in servo-type applications that use a bipolar velocity signal that determines direction. SpeedMaximum speed 0 Acceleration t Acceleration (time) setting Speed Speed 1 Speed 2 t Multi-speed Profile SpeedForward move Reverse movet Bi-directional Profile Phone: 800.894.0412 - Fax: 888.723.4773 - Web: www.clrwtr.com - Email: [email protected]
Frequently Asked Questions Geting Started 1–18 Frequently Asked Questions Q.What is the main advantage in using an invert er to drive a motor, compared to alternative solutions? A. An inverter can vary the motor speed with very little energy loss, unlike mechanical or hydraulic speed control solutions. The re sulting energy savings can often pay for the inverter in a relatively short time. Q. The term “inverter” is a little confusing, since we also use “drive” and “amplifier” to describe the electronic unit that controls a motor. What does “inverter” mean? A. The terms are used somewhat interchang eably in industry. Nowadays, the terms drive , variable-frequency drive, variable-speed drive, and inverter are generally used to describe electronic, microprocessor-based motor speed controllers. In the past, variable speed drive also referred to various mech anical means to vary speed. Ampli- fier is a term almost exclusively used to de scribe drives for servo or stepper motors. Q. Although the SJ700 2 inverter is a variable speed drive, can I use it in a fixed-speed appli- cation? A. Yes, sometimes an inverter can be used simply as a “soft-start” device, providing controlled acceleration and deceleration to a fixed speed. Other functions of the SJ700 2 may be useful in such a pplications, as well. However, using a variable speed drive can benefit many types of industria l and commercial motor applications, by providing controlled accelera tion and deceleration, high torque at low speeds, and energy savings over alternative solutions. Q. Can I use an inverter and AC induction motor in a positioning application? A. That depends on the required precision, and the slowest speed the motor must turn and still deliver torque. The SJ700 2 inverter will deliver 200% rated torque while turning the motor at only 0.3 Hz. DO NOT use an inverter if you need the motor to stop and hold the load position without the aid of a mechanical brake (use a servo or stepper motion control system). Q. Does the optional digital operator interfa ce or the PC software (DOP Professional) provide features beyond what is avai lable from the keypad on the unit? A. Yes. However, note first that the same se t of parameters and functions are equally accessible from either the unit’s keypad or from remote devices. The DOP Profes- sional PC software lets you save or load in verter configurations to or from a disk file. And, the hand-held digital operator provides hard-wired terminals, a safety require- ment for some installations. Q. Why does the manual or othe r documentation use terminology such as “200V class” instead of naming the actual voltage, such as “230 VAC?” A. A specific inverter model is set at the factory to work across a voltage range particular to the destination country for that model. The model specific ations are on the label on the side of the inverter. A European 200V cl ass inverter (“EU” marking) has different parameter settings than a USA 200V class inverter (“US” marking). The initialization procedure (see “ Restoring Factory Default Settings” on page 6–16) can set up the inverter for European or US commercial voltage ranges. Q. Why doesn’t the motor have a neutral c onnection as a return to the inverter? A. The motor theoretically represents a “balanced Y” load if all three stator windings have the same impedance. The Y connection allows each of the three wires to alter- nately serve as input or retu rn on alternate half-cycles. Q. Does the motor need a chassis ground connection? A. Yes, for several reasons. Most importantly, this provides protection in the event of a short in the motor that puts a hazardous voltage on its housing. Secondly, motors exhibit leakage currents that increase with aging. Lastly, a grounded chassis generally emits less electrical nois e than an ungrounded one. Phone: 800.894.0412 - Fax: 888.723.4773 - Web: www.clrwtr.com - Email: [email protected]
SJ7002 Inverter Getting Started 1–19 Q.What type of motor is compatible with the Hitachi inverters? A. Motor type – It must be a three phase AC induction motor. Use an inverter-grade motor that has 800V insulation for 200V cl ass inverters, or 1600V insulation for 400V class. Motor size – In practice, it’s better to find th e right size motor for your application; then look for the inverter to match the motor. NOTE: There may be other factors that will affect motor selection, including heat dissipation, motor operating speed profile, enclosure type, and cooling method. Q.How many poles should the motor have? A. Hitachi inverters can be configured to oper ate motors with 2, 4, 6, or 8 poles. The greater the number of poles, the slower the top motor speed will be, but it will have higher torque at the base speed. Q. Will I be able to add dynamic (resistive) braking to my Hitachi SJ700 2 drive after the initial installation? A. Yes. Models SJ700-004XXX through SJ700-220XXX have built-in dynamic braking units. You can add an extern al resistor to these models to improve braking perfor- mance. Models SJ700-300XXX through SJ700-4000XXX require you to add an external braking unit. The braking resistor connects to the external braking unit for those models. More inform ation on dynamic braking is located in Chapter 5. Q. How will I know if my applicatio n will require resistive braking? A. For new applications, it may be difficult to tell before you actually test a motor/drive solution. In general, some ap plications can rely on system losses such as friction to serve as the decelerating force, or otherw ise can tolerate a long decel time. These applications will not need dynamic braking. However, applications with a combina- tion of a high-inertia load and a required short decel time will ne ed dynamic braking. This is a physics question that may be answered either empirically or through extensive calculations. Q. Several options related to elec trical noise suppression are available for the Hitachi invert- ers. How can I know if my applicati on will require any of these options? A. The purpose of these noise filters is to redu ce the inverter electrical noise so the operation of nearby electrical devices is not affected. Some applications are governed by particular regulatory agenci es, and noise suppression is mandatory. In those cases, the inverter must have the corresponding noi se filter installed. SJ700 models from -004XXX (0.4kW) to -1500XXX (150kW) have built-in EMC filters. Other applica- tions may not need noise suppression, unless you notice electrical interference with the operation of other devices. Q. The SJ700 2 features a PID loop feature. PID loops are usually associated with chemical processes, heating, or process industries in general. How could the PID loop feature be useful in my application? A. You will need to determine the particular main variable in your application the motor affects. That is the process variable (PV) for the motor. Over time, a faster motor speed will cause a faster change in the PV than a slow motor speed will. By using the PID loop feature, the inverter commands the motor to run at the optimal speed required to maintain the PV at the desire d value for current conditions. Using the PID loop feature will require an additional sensor and other wiring, and is considered an advanced application. Phone: 800.894.0412 - Fax: 888.723.4773 - Web: www.clrwtr.com - Email: [email protected]