Effective December 2019 PowerXL DG1 Series VFD
PowerXL DG1 Series VFDInstallation manualEffective December 2019Supersedes March 2019
DISCLAIMER OF WARRANTIES AND LIMITATION OF LIABILITYThe information, recommendations, descriptions, and safety notations in this document are based on manufacturer’sexperience and judgment and may not cover all contingencies. If further information is required, a sales representativeshould be consulted. Sale of the product shown in this literature is subject to the terms and conditions outlined inappropriate manufacturer selling policies or other contractual agreement between manufacturer and the purchaser.THERE ARE NO UNDERSTANDINGS, AGREEMENTS, WARRANTIES, EXPRESSED OR IMPLIED, INCLUDING WARRANTIESOF FITNESS FOR A PARTICULAR PURPOSE OR MERCHANTABILITY, OTHER THAN THOSE SPECIFICALLY SET OUT INANY EXISTING CONTRACT BETWEEN THE PARTIES. ANY SUCH CONTRACT STATES THE ENTIRE OBLIGATION OF THEMANUFACTURER. THE CONTENTS OF THIS DOCUMENT SHALL NOT BECOME PART OF OR MODIFY ANY CONTRACTBETWEEN THE PARTIES.In no event will the manufacturer be responsible to the purchaser or user in contract, in tort (including negligence), strictliability, or otherwise for any special, indirect, incidental, or consequential damage or loss whatsoever, including but notlimited to damage or loss of use of equipment, plant or power system, cost of capital, loss of power, additional expensesin the use of existing power facilities, or claims against the purchaser or user by its customers resulting from the use of theinformation, recommendations, and descriptions contained herein. The information contained in this manual is subject tochange without notice.Cover Photo: Eaton PowerXL Series DriveiiPOWERXL SERIES VFD MN040002EN—December 2019 www.eaton.com
PowerXL DG1 Series VFDSupport servicesSupport servicesThe goal of Eaton is to ensure your greatest possiblesatisfaction with the operation of our products.We are dedicated to providing fast, friendly, and accurateassistance. That is why we offer you so many ways to getthe support you need. Whether it is by phone, fax, or email,you can access Eaton’s support information 24 hours a day,seven days a week.Our wide range of services is listed below.You should contact your local distributor for product pricing,availability, ordering, expediting, and repairs.WebsiteUse the Eaton Website to find product information.You can also find information on local distributors orEaton’s sales offices.Website addresswww.eaton.com/drivesEatonCare Customer Support CenterCall the EatonCare Support Center if you need assistancewith placing an order, stock availability or proof of shipment,expediting an existing order, emergency shipments, productprice information, returns other than warranty returns, andinformation on local distributors or sales offices.Voice: 877-ETN-CARE (386-2273) (8:00 a.m.–6:00 p.m. EST)After-Hours Emergency: 800-543-7038 (6:00 p.m.–8:00 a.m. EST)Drives Technical Resource CenterVoice: 877-ETN-CARE (386-2273) option 2, option 6(8:00 a.m.–5:00 p.m. Central Time U.S. [UTC –6])email: TRCDrives@Eaton.comFor customers in Europe, contactPhone: 49 (0) 228 6 02-3640Hotline: 49 (0) 180 5 223822email: tersalesPOWERXL SERIES VFD MN040002EN—December 2019 www.eaton.comiii
PowerXL DG1 Series VFDTable of contentsSAFETYBefore commencing the installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ixDefinitions and symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .xHazardous high voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .xDANGER5 MIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .xWarnings and cautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .xCHAPTER 1—POWERXL SERIES OVERVIEWHow to use this manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1Receiving and inspection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1Real time clock battery activation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1Rating label . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2Carton labels (U.S. and Europe). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2Catalog number system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3Power ratings and product selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4DG1 replacement parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8DH1 replacement parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11CHAPTER 2—ENGINEERING CONSIDERATIONSIntroduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15Electrical power network . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16Input voltage and frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16Input voltage balance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16Total harmonic distortion (THD) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17Reactive power compensation devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17CHAPTER 3—PRODUCT OVERVIEWComponent identification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18Selection criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20Proper use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20Maintenance and inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21Service and warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21CHAPTER 4—SAFETY AND SWITCHINGFuses and cable cross-sections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22Cables and fuses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22Residual-current device (RCD) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22Leakage current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23Input contactor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23EMC Measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24CHAPTER 5—MOTOR AND APPLICATIONMotor selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25Connecting motors in parallel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25Parallel connection of several motors to one frequency inverter . . . . . . . . . . . . . . . .26Bypass operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28Connecting EX motors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28ivPOWERXL SERIES VFD MN040002EN—December 2019 www.eaton.com
PowerXL DG1 Series VFDTable of contents, continuedCHAPTER 6—INSTALLATION REQUIREMENTSElectrical installation warnings and cautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29Standard mounting instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31Standard drive mounting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32FR6 wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37Power wiring selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38Cable selection: Power and motor leads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38Line (Mains) and motor cable installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38Connection tightening torque . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39Cable routing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40Wiring the VFD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40Rubber grommet installation instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41Control board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .47Safe torque off (STO) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .48Connection to power section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .48Three-phase input connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .48Terminal designations in the power section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .48Ground connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .48Product modified sticker . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .49Checking the cable and motor insulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .49CHAPTER 7—EMC INSTALLATIONEMC Measures in the control panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .50Earthing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .50Screen earth kit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .50Installation requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .51International EMC protection cable requirements . . . . . . . . . . . . . . . . . . . . . . . . . . .52Installation in corner-grounded network and IT system . . . . . . . . . . . . . . . . . . . . . . .53APPENDIX A—TECHNICAL DATA AND SPECIFICATIONSTechnical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .55APPENDIX B—INSTALLATION GUIDELINESCable and fuse sizing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .58Temperature deratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .63Heat loss data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .70Brake resistor sizing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .71Efficiency ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .72APPENDIX C—DIMENSION DRAWINGSAPPENDIX D—SAFETY INSTRUCTIONS FOR UL AND CULUL Standards compliance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .90Field wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .93APPENDIX E—STO FUNCTIONDescription of safety function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .100Requirement for installation, commission, maintenance . . . . . . . . . . . . . . . . . . . . .102Requirements of proof test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .102APPENDIX F—UL CERTIFICATE OF COMPLIANCEUL certificate of compliance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .103CE declaration of conformance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .103POWERXL SERIES VFD MN040002EN—December 2019 www.eaton.comv
PowerXL DG1 Series VFDList of eFigureFigureFigureFigureFigurevi1. RTC battery connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12. Rating label—DG1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23. Rating label—DH1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24. Carton label—DG1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25. Carton label—DH1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26. Catalog numbering system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37. Drive system (PDS power drive system) . . . . . . . . . . . . . . . . . . . . . . . . .158. AC power networks with grounded neutral point (TN-/TT networks) . . . . .169. Description of the PowerXL Series . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1810. Block diagram, elements of PowerXL frequency inverters . . . . . . . . . . . .1911. Selection criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2012. Identification on the FI circuit breakers . . . . . . . . . . . . . . . . . . . . . . . . . . .2213. EMC Measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2414. Parallel connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2615. Example of a motor ratings plate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2616. Star and delta circuit types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2617. V/Hz characteristic curve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2718. Bypass motor control (example) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2819. Mounting space . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3020. Open Drives FR0–FR6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3121. FR6 wiring layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3722. Brake resistor wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3823. Input power and motor cable stripping lengths . . . . . . . . . . . . . . . . . . . .3924. Ground wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4225. Terminal block layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4526. Basic internal control wiring diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . .4627. PowerXL variable frequency drive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4728. Connection to power section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4829. Grounding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4830. FR0 grounding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4931. Product modified sticker . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4934. EMC-Compliant Setup—230 Vac, 460/480 Vac, 600 Vac . . . . . . . . . . . . .5135. Cable description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5236. Location of the EMC Screw in Frame 0 . . . . . . . . . . . . . . . . . . . . . . . . . .5337. Locations of the EMC Screw in Frame 1 and Frame 3 . . . . . . . . . . . . . . .5338. Locations of EMC and MOV Screws for Frame 2 and Frame 4 . . . . . . . .5439. Locations of the EMC Screws in Frame 5 and Frame 6 . . . . . . . . . . . . .5440. FR0 Dimension drawing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7741. FR1 Dimension drawing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7842. FR1 Dimension drawing flange mount . . . . . . . . . . . . . . . . . . . . . . . . . . .7943. FR2 Dimension drawing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8044. FR2 Dimension drawing flange mount . . . . . . . . . . . . . . . . . . . . . . . . . . .8145. FR3 Dimension drawing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8246. FR3 Dimension drawing flange mount . . . . . . . . . . . . . . . . . . . . . . . . . . .8347. FR4 Dimension drawing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8448. FR4 Dimension drawing flange mount . . . . . . . . . . . . . . . . . . . . . . . . . . .8549. FR5 Dimension drawing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8650. FR5 Dimension drawing flange mount . . . . . . . . . . . . . . . . . . . . . . . . . . .8751. FR6 Dimensional drawing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8852. FR6 Dimensional drawing flange mount . . . . . . . . . . . . . . . . . . . . . . . . . .8953. Functional block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10054. Reliability block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10055. STO terminal block in PowerXL control board . . . . . . . . . . . . . . . . . . . . .10256. Thermistor STO wiring diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .102POWERXL SERIES VFD MN040002EN—December 2019 www.eaton.com
PowerXL DG1 Series VFDList of tablesTable 1. Common abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1Table 2. Open Type IP20 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4Table 3. Type 1/IP21 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4Table 4. Type 12/IP54 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5Table 5. Open Type IP20 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5Table 6. Type 1/IP21 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6Table 7. Type 12/IP54 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6Table 8. Type 1/IP21 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7Table 9. Type 12/IP54 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7Table 10. Frame 0 . . . . . . . . . . . .
Installation manual PowerXL DG1 Series VFD. ii POWERXL SERIES VFD MN040002EN—December 2019 www.eaton.com . 21 Service and warranty . Rubb
PowerXL DG1 Series VFD PowerXL DG1 Series VFD MN040002EN—July 2015 www.eaton.com i Disclaimer of Warranties and Limitation of Liability The information, recommendations, descriptions, and safety notations in this document are based on Eaton's experience and judgment and may not cover all contingencies. If further
PowerXL DG1 Series VFD PowerXL DG1 Series VFD MN040002EN—July 2015 www.eaton.com i Disclaimer of Warranties and Limitation of Liability The information, recommendations, descriptions, and safety notations in this document are based on Eaton's experience and judgment and may not cover all contingencies. If further
ii POWERXL FR7 AND FR8 SERIES VFD MN040040EN—June 2018 www.eaton.com DISCLAIMER OF WARRANTIES AND LIMITATION OF LIABILITY The information, recommendations, descriptions, and safety notations in this docu
ACE KIT 1 Pre-filter and hardware (one-piece) ACE KIT 2 Filter assembly (one-piece) ACE KIT 3 Blower, manifold and hardware (one-piece) ACE KIT 7 3/ 8” glass window ACE KIT 8 5/ 8” glass window ACE KIT 9 Shroud replacement kit Note: 600 suffix option can only be used for ACE-DG1 units with nominal HP of 5 or less. Drive fan replacement kits .
The devices of the series Power XL DG1 have a real time clock (RTC), which enables to amend status messages with a time stamp or to change operating conditions in a time controlled manner. This Application Note describes the handling of the battery, the setting of the RTC and the parameteriza-tion of time based actions.
You should contact your local distributor for product pricing, availability, ordering, expediting, and repairs. . Power ratings and product selection . Chapter 2—Keypad overview Keypad buttons .10 LED lights .
December 2014 Monday December 1. Tuesday December 2. Wednesday December 3. Thursday December 4. Friday December 5. Saturday December 6. Sunday December 7. Monday December 8. Tuesday December 9 - Fall Semester Ends. Wednesday December 10- Reading Day. Thursday December 11- Final Examinatio
business,insurance risk transformationor activities directly arising frominsurance risk transformation(for example,general insurance businessoraccepting deposits) thefirmmay choose to comply with Principles6, 7, 8 and 9 as if all itsclientswerecustomers. Alternatively, it may choose to distinguish betweeneligible counterpartiesandcustomersin complying with thosePrinciples. If it chooses to .
