Altivar 71 Output filters Selection Guide Producto y

Altivar 71 Output filters Selection Guide Producto y Versión: ATV 61/71 Revisión 1. 0 2. 0 Fecha Autor 1/2011 3/2011 Sergio Núñez Centro de Competencia Técnica Modificaciones Primera versión Actualización diagrama de selección y contenido

ATV 71: Output filters Selection Guide Summary 1. Selection Diagram 2. Causes of motor overvoltages 3. Multiplication factors > > Switching frequency influences Motors in parallel 4. Selection Table 5. Overvoltage and dv/dt limitation options > > > SVL overvoltage limitation function Motor Choke. Sinus Filter 6. Adequation of the motor Schneider Electric - Sergio Núñez - L 2 TSC Spain - 01. 2011 2

Output Filters Selection Diagram 1 Schneider Electric - Sergio Núñez - L 2 TSC Spain - 01. 2011 3

Output Filters Selection Diagram 2 5 4 6 3 Schneider Electric - Sergio Núñez - L 2 TSC Spain - 01. 2011 4

Causes of motor overvoltages ● The switching of the output voltage on the output of a drive by the IGBT bridge generates rapid variations in voltage (d. V/dt). + VDC bus e. g. 400 * 2 = 566 V Drive output voltage (PWM) d. V/dt 2 to 10 k. V/µS 0 V Motor current nearly sinusoidal - VDC bus Schneider Electric - Sergio Núñez - L 2 TSC Spain - 01. 2011 5

Causes of motor overvoltages ● Overvoltages are generated by reflected waveforms due to d. V/dt and to poor impedance matching between the motor and the motor cable. ● The amplitude and the d. V/dt are principally functions of the cable length and the modulation technique. overvoltage d. V/dt l cable Overvoltage at the motor terminals Typically up to 2 x V bus DC + Vdc - Vdc ex U main =400 Vac Motoring Quadrant Û = 400 x. SQR 2 x 2 = 1132 V Generating Quadrant (braking) Û = 790 x 2 = 1580 V Sometimes in certain cases the overvoltage can be greater than 2 Vdc. . . Schneider Electric - Sergio Núñez - L 2 TSC Spain - 01. 2011 6

Causes of motor overvoltages ● Overvoltages and d. V/dt can degrade the insulation of motor windings and cables. ● This problem is generally above than 400 V and for motors not having insulation compatible with variable speed drives (class F). ● Overvoltages can be destructive with cable lengths of 20 meters or above. ● The can be greater than 2 Vdc in the case of PWM with short tmin (ex 2µS for 200 m 4 k. W) Remarks : The d. V/dt gradient is as bad for motor windings as the overvoltage itself (corona effect). And very short wires can also be a problem because of low inductance and parasitic capacitance. Schneider Electric - Sergio Núñez - L 2 TSC Spain - 01. 2011 7

Multiplication factors ● Factors to be taken into account: ● If parallel cables are used, the cable lenght to be considered must be multiplied by 2, ● If motors are in parallel, the cable lenght to be considered must be the sum of all motor cable lengthes. ● Note: a multiplication factor can be used if the swithching frequency used is greater than the default value, but in this case, the use of output filter is not allowed. Schneider Electric - Sergio Núñez - L 2 TSC Spain - 01. 2011 8

Switching frequency influences When using “SFR” parameter for example between 4 and 8 k. Hz the losses increase by 1, 3 in tri-phase modulation so it is necessary to dicrease the length of motor cable. Recommendation for length of motor cable in function of switching frequency. (1) These factors are theorical values. Note: a multiplication factor can be used if the swithching frequency used is greater than the default value, but in this case, the use of output filter is not allowed. Schneider Electric - Sergio Núñez - L 2 TSC Spain - 01. 2011 9

Motors in parallel • The cable length to be considered for choosing an output filter is the sum of all the cable lengths (ex L 1+L 2+3 L 3). • Minimize the cable length (drive as close as possible to the motors). L 1 L 2 L 3 Schneider Electric - Sergio Núñez - L 2 TSC Spain - 01. 2011 10

Selection table depending on cable length Output filter recommendation according to motor cable length and previous multiplication factors. Schneider Electric - Sergio Núñez - L 2 TSC Spain - 01. 2011 11

Software overvoltage limitation function The over voltage software function (SUL) permits the limitation of the over voltage in motor terminals to 2 times the DC bus voltage. To do this, the minimum time between two PWM voltage pulses is adjustable as a function of the cable length (from 6 to 10µS) by means of the optimization paramenter “SOP”. The value of the “SOP” parameter corresponds to the attenuation time of the cable used. It is defined to prevent the superimposition of voltage refections resulting from long cable lengths. The SUL function is useful by itself below certain wiring distances. For longer cable lengths it is necessary to additional output filters. This function is based on the elimination of shorter pulses generated in the PWM output of the drive. On the other hand, the elimination of these pulses leads to a little loss of torque estimated about 3%, that leads in a lower dynamic performance. Schneider Electric - Sergio Núñez - L 2 TSC Spain - 01. 2011 12

Software overvoltage limitation function A PWM pulse too short with respect to the time constant of the cable can lead to the superposition of 2 oscillations and generate and overvoltage > 2*V bus DC Schneider Electric - Sergio Núñez - L 2 TSC Spain - 01. 2011 13

Software overvoltage limitation function Function not activated overvoltages greater than 2 Vdc + 2 Vdc Time [s] + 2 Vdc SUL function activated Time [s] ● The increase of « tmin » slightly degrades the performance but in a proportion that is acceptable with a long cable length. ● The switching frequency is automatically limited to the factory setting (2. 5 k. Hz to 4 k. Hz) Schneider Electric - Sergio Núñez - L 2 TSC Spain - 01. 2011 14

Software overvoltage limitation function The tables in the programmation manuals gives examples of correspondence between “SOP” parameter and the length of cable between the drive and the motor. Unshielded "GORSE" cable type H 07 RN-F 4 Gxx: * These tables are not available for drives of power higher than 75 k. W. Schneider Electric - Sergio Núñez - L 2 TSC Spain - 01. 2011 15

Software overvoltage limitation function The tables in the programmation manuals gives examples of correspondence between “SOP” parameter and the length of cable between the drive and the motor. Shielded "BELDEN" cable Type 2950 x: * These tables are not available for drives of power higher than 75 k. W. Schneider Electric - Sergio Núñez - L 2 TSC Spain - 01. 2011 16

Software overvoltage limitation function Summary: ● Principal ● A PWM voltage pulse time that is very short in comparison to the period can generate an overvoltage >2 times the DC bus voltage during a positive to negative transition. ● This function permits the limitation of the overvoltage to 2 times the DC bus voltage. ● To do this, the minimum time between two PWM voltage pulses is adjustable as a function of the cable length (from 6 to 10µS). ● This function is activated by the parameter SUL ● Applications ● Protection of motors against overvoltages greater than 2 Vbus DC ● Cable lengths up to 150 m Schneider Electric - Sergio Núñez - L 2 TSC Spain - 01. 2011 17

Maximum cable length depending on motor choke selection See catalog in order to verify the maximum cable length depending on output filter selection. Schneider Electric - Sergio Núñez - L 2 TSC Spain - 01. 2011 18

Sinus Filter Sinus filter is a low bandwidth filter with a cutoff frequency below the switching frequency (4 to 8 k. Hz only). Sinus filter is the best solution with ATV 71 to solve overvoltage at the motor terminal for long motor cable until 600 m or 1000 m depending on the drive power rate. Sinus filter is also the best way to reduce motor noise. For high power rates sinus filter only allows U/F motor control law and low dynamic. Vector control law in open loop is only posible until 75 k. W N 4 or 45 k. W M 3 X voltage supply. See catalog in order to select the rigth reference. In next page you will find a table with maximum cable length depending on sinus filter reference. Schneider Electric - Sergio Núñez - L 2 TSC Spain - 01. 2011 19

Sinus Filter Maximum cable length depending on sinus filter reference: For motors in parallel, the sum of all the cable lengths must be taken into consideration. Due to capacitor between phases and ground at the output of the sinus filters, the maximum length of each cable must be divided: ● by 2, 5 for two motors ● by 4 for three motors ● by 6 for four motors Schneider Electric - Sergio Núñez - L 2 TSC Spain - 01. 2011 20

Output side of ATV 61/71 Motor choke vs. Sinus filter ● Motor choke … ● is much cheaper than a sinus filter ● has a smaller size, nearly no voltage drop, less losses ● Has a better peak voltage limitation against earth ● Allows all motor control laws (Sinus filter in HHP only allows U/f and low dynamic) ● No drive derating necessary (Sinus filter operates at 4 k. Hz!) Altivar 61/71 M 1 3 Motor choke Schneider Electric - Sergio Núñez - L 2 TSC Spain - 01. 2011 VS. 21

Adequation of the motor ● Check is the selected motor is compatible with pre-selected drive and options 1. Pe-selected configuration: L < Lmax with no motor filter ●Motor insulation must be compatible for the use with the variable speed drive. Refer to the next slide. ●If not, it is required to add motor choke to protect the motor again dv/dt and over voltages Note: activation of the SUL function and adjustment of the parameter SOP according to the type and length of cable suppress the over voltages exceeding 2 times the bus voltage. 2. Pre-selected configuration: L > Lmax with motor choke and filter ●The motor is protected against d. V/d. T ●Motor protection against over-voltages can be considered by SUL function activation. Schneider Electric - Sergio Núñez - L 2 TSC Spain - 01. 2011 22

Adequation of the motor Motor protection against d. V/d. T ● d. V/d. T protection : customer must be aware of the motor type intended to be used in its application, ● We consider here the d. V/d. T on motor terminals. ● Depending on this type, IEC 60034 -17 defines a table for admissible d. V/d. T levels. Overvoltage k. V ● A – motors up to 500 V used with a variable speed drive ● B – motors up to 600 V used with a variable speed drive ● C – motors not specified for use with variable speed drives (IEC 60034 -17) Rise time µS Schneider Electric - Sergio Núñez - L 2 TSC Spain - 01. 2011 23

Adequation of the motor Motor protection against d. V/d. T ● Independently of motor cable length, the limitation of d. V/d. T to 500 V/µs or 1 k. V/µs (depending on supply voltage) is done by using a motor choke: ● d. V/d. T limitation values with motor chokes: < 500 V/µs @ 400 V < 750 V/µs @ 500 V < 1000 V/µs @ 690 V ● The motor choke also permits to reduce peak voltage (*). < 1000 V @ 400 V < 1150 V @ 460 V < 1800 V @ 690 V * (These values apply in motor mode operation). ● The use of a motor choke is mandatory in case of retrofit of an installation with an old motor. ● Supression of the d. V/d. T : ● The suppression of the d. V/d. T on motor terminals is done by using a sinus filter. Schneider Electric - Sergio Núñez - L 2 TSC Spain - 01. 2011 24

Adequation of the motor Motor protection against over-voltage ● A PWM voltage pulse time that is very short can generate an overvoltage >2 times the DC bus voltage during a positive to negative transition. ● The variable speed drives integrates the SVL function, that permits the limitation of the over-voltage to 2 times the DC bus voltage. ● In generative mode, the DC bus level will regulated at the DC bus braking level, that can be adapted via UBR parameter: ●ATV 71 ooo. M 3 p: factory setting 395 V. ●ATV 71 ooo. N 4: factory setting 785 V. ●ATV 71 ooo. S 6 X: factory setting 980 V. ●ATV 71 ooo. Y: factory setting 1127 V or 1080 V according to rating. ● The activation of SVL function will limit the setting range of the switching frequency of the variable speed drive. Schneider Electric - Sergio Núñez - L 2 TSC Spain - 01. 2011 25

IEC 60034 -25 ● Find more information about ● ● ● Motor cabling Motor Isolation Reduction of voltage stress Bearing problems and causes Motor filters Drive principals Schneider Electric - Sergio Núñez - L 2 TSC Spain - 01. 2011 26

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