AXICO ANTI-STALL® Axial flow fan Fläkt

FPAC and FPMC axial-flow fans Page 34Electric motorsThis catalogue section deals with totally enclosed, footmounted, three-phase squirrel cage motors for 50 Hz.The two-speed motors are adapted for driving fans.Quotations for motors incorporating temperature sensors will be submitted on request.APAL Single-speed motorsARALTwo-speed motors, with speed ratio of 1:2 and one stator winding (Dahlander-coupled)ATAL Two-speed motors, with speed ratio 1:1.5 and separate stator windingsDetermination of the starting timeWhenever fans or fan drives are presented with a specificmotor, this is rated for direct on-line starting. If a differentmotor is selected or if a star-delta start is employed, the startingtime must be checked by calculation.Use the following formulae to calculate the starting time fordirect on-line and star-delta starting:Direct on-line startingStar-delta startingPermissible starting timeThe maximum permissible starting times for an individual startwith the motor in cold condition are tabulated below.Max. starting time, secondsMotor Method of starting for an individual startsizeNumber of poles4 6132160-225250280315355t =t =J x nf ² x 10 - ³Mmax Mst46 P + -M MPfJ x nf ² x 10 - ³1 Mmax 1 Mst46 Px + x -3 M 4 MPfDirect on-line starting 12 20Star-delta starting 36 60Direct on-line starting 15 20Star-delta starting 45 60Direct on-line starting 15 20Star-delta starting 45 60Direct on-line starting 18 17Star-delta starting 54 51Direct on-line starting 18 16Star-delta starting 54 48Direct on-line starting 20 18Star-delta starting 60 54In most cases, it must be possible to restart a motor immediatelyafter it has stopped. A good rule is therefore to utilise only onethirdof the starting time listed in the table.NOTE!A star-delta starter may be used for starting a motor, providedthat the motor is delta-coupled. During the starting process, themotor is star-coupled, and the torque it develops is thereforereduced. Check that the torque curve of the motor is higher thanthan the torque curve of the fan up to 90% of the synchronousspeed. If no torque curves are available for the motor, the followingformula can be used with adequate accuracy for determiningthe minimum motor rating.PY/D =2.6x Pf MmaxMIf star-delta starting is employed, the starter should be set tothe star setting for a period of time corresponding to the startingtime calculated as described above, and should then be switchedover to the delta setting.Symbols usedP = rated output of the motor ........................................ kWPf 1) = fan power demand at rated speed(incl. belt-drive losses if the fan is belt-driven ......... kWPY/D = Minimum motor rating at which star-deltastarting is possible .................................................. kWMst = ratio of motor starting torque to normal torqueMMmax = ratio of max. motor torque to normal torqueMnf = rated speed of fan .............................................. r/minJ = moment of inertia of the system,referred to the fan shaft 2) .................................. kg m²t = starting time .............................................................. s1) Also specified as PM in other catalogue sections.2) The moment of inertia of the fan impeller is specified in the appropriate fan chart.The moment of inertia of the motor can normally be neglected.Ordering keyMotor, single-speedMotor, two-speedspeed ratio 1:1.5speed ratio 1:2Number of poles 1) (see motor tables): 4,6Rated output 1) (see motor tables): The first three digits ofcode suffix b specify kW in integers, and the last two aredecimals. Example: Code suffix 00175 denotes 1.75 kW.Supply voltageSingle-speed motor1 =220-240 V delta/380-420 V star (sizes 63-250) 2)220 V delta/380 V star (sizes 280-355) 2)380-420 V delta (sizes 63-250)2 = 380 V delta (sizes 280-355)4 = 415 V delta (sizes 280-355)5 = 500 V star (sizes 63-100), 500 V delta (sizes 112-355)Two-speed motor2 = 380 V 5 = 500V1) For the higher speed of a two-speed motor.2) Star-delta starting is not possible if the motor is star-wired.APAL-a-bbbbb-c-0ATAL-a-bbbbb-c-0ARAL-a-bbbbb-c-0