4 Project Planning - download.sew-eurodrive.com · Usys System voltage, voltage of the supplying inverter V UBr Operating voltage of the brake V x Distance between overhung load application

EXG – Explosion-Proof Drives 45

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Drive and gear unit selection dataProject Planning

4 Project Planning4.1 Drive and gear unit selection data

Certain data of the application have to be provided to being able to precisely define thecomponents for your drive. The abbreviations used for project planning are summarizedin the following table:

Designation Meaning Unit

ϕ Rotational clearance `

η Gear unit efficiency for Mapk

a, b, f Gear unit constants as regards the overhung load conversion mm

c Gear unit constants as regards the overhung load conversion Nmm

a0, a1, a2 Gear unit constants as regards the rise in temperature in the gear unit

FA Axial load (tension and compression) on the output shaft N

fk Speed ratio

FR Overhung load on the output shaft N

FRapkMaximum permitted overhung load at the output shaft for short-time duty (load application point is the middle of the shaft end) N

FRamaxMaximum permitted overhung load at the output shaft for continuous duty (load application point is the middle of the shaft end) N

FRepkMaximum permitted overhung load at the input shaft for short-time duty (load application point is the middle of the shaft end) N

FRemaxMaximum permitted overhung load at the input shaft for continuous duty (load application point is the middle of the shaft end) N

H Installation altitude m above sea level NN

I0 Current consumption of the motor at M0 A

Imax Maximum permitted motor current (root-mean-square value) A

Ins. cl. Thermal classification of the motor

i Gear unit reduction ratio

IM Gear unit mounting position (international mounting position) M1 – M6

IP.. Degree of protection according to IEC60034-5

JA Mass moment of inertia of the adapter kgm2

JG Mass moment of inertia of the gear unit with reference to the input shaft kgm2

JGA Mass moment of inertia of the gear unit including adapter with reference to the input shaft kgm2

Jext Mass moment of inertia (external) reduced on motor shaft kgm2

JMot Mass moment of inertia of the motor kgm2

JL Mass moment of inertia of the load kgm2

k Inertia ratio Jext / JMot

l Length of output shaft mm

M1 – Mn Output torque in time period t1 to tn Nm

M0Thermally permitted output torque of the motor in continuous duty at low speed (not to be confused with standstill torque) Nm

Table continued on next page.

46 EXG – Explosion-Proof Drives

4 Drive and gear unit selection dataProject Planning

MaDYN Dynamic output torque assumed for the drive in project planning Nm

Maeff Effective torque for component testing calculated in project planning Nm

Makub Effective torque for bearing testing calculated in project planning Nm

Mamax Maximum permitted output torque for continuous duty Nm

Mapk Maximum permitted output torque for short-time duty Nm

MaNOTAUS Maximum permitted output emergency stop torque, max. 1000 emergency stops Nm

Math Effective torque for thermal testing calculated in project planning Nm

MB Rated brake torque Nm

Mpk Dynamic limit torque of the servomotor Nm

Meff Effective torque requirement (in relation to the motor) Nm

Mmax Maximum output torque assumed for the drive in project planning Nm

ML Mounting location (UL)

napk Maximum permitted output speed for short-time duty rpm

nepk Maximum permitted input speed for short-time duty rpm

nem Mean input speed rpm

nam Mean output speed rpm

nak Breakpoint speed (output) rpm

nN Nominal speed rpm

n1 – nn Output speed in time period t1 to tn rpm

netn_pk Maximum input speed in time period n rpm

PBr Braking power W

PBr_pk Peak braking power W

PBr_eff Effective braking power W

PBr_tn Braking power in time period tn W

S.., ..% cdf Duty type and cyclic duration factor cdf in %; the exact load cycle can be entered instead.

t1 – tn Time period 1 to n s

tz Cycle time s

TAmb Ambient temperature °C

Usys System voltage, voltage of the supplying inverter V

UBr Operating voltage of the brake V

x Distance between overhung load application point and shaft shoulder mm

FRmax Calculated auxiliary variable

FRkub Calculated auxiliary variable

Designation Meaning Unit


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Drive and gear unit selection dataProject Planning

4.1.1 Determining the application data

It is necessary to have data on the machine to be driven (mass, speed, setting range,etc.) to project the drive correctly.

This data helps to determine the required power, torque and speed. Refer to the SEWpublication "Drive Engineering - Practical Implementation / Drive Planning" or the SEWproject planning tool "SEW Workbench" for assistance.

4.1.2 Selecting the correct driveThe appropriate drive can be selected once the power and speed of the drive have beencalculated and with regard to mechanical requirements.

4.1.3 Required motor dataAs the dimensions of servomotors are not standardized, the following motor data mustbe known to select the appropriate adapter:

• Shaft diameter and length

• Flange dimensions (edge length, diameter, centering shoulder and hole circle)

• Maximum torque

SEW-EURODRIVE will gladly assist you with selection and project planning.


4 Project planning procedure for EDR. drives – line poweredProject Planning

4.2 Project planning procedure for EDR. drives – line poweredThe following flow diagram illustrates the project planning procedure for a line-powereddrive.

You find detailed information on the project planning for EDR. motors in the "Explosion-Proof AC Motors" catalog.

Necessary information regarding the machine to be driven– Data of the application

Calculation of the relevant application data– Torque– Power– Speeds– Overhung and axial loads– Travel diagram

↓ ↓

Drive selection– Selection of the gear unit type

– Determining the necessary service factor– Select the gearmotor using the selection tables for the appropriate unit categories– Selection of the necessary braking torque, brake size, and brake control

↓

Select the options– Brake– Manual brake release– Backstop– 2. Shaft end

↓

Make sure that– the permitted overhung and axial loads are not exceeded– the permitted starting frequency is not exceeded– the maximally permitted braking work per switching operation is not exceeded.


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Project planning procedure for EDR. drives – inverter poweredProject Planning

4.3 Project planning procedure for EDR. drives – inverter poweredThe following flow diagram illustrates the project planning procedure for a drive. Thedrive consists of a gearmotor that is powered by an inverter.

For detailed information about project planning for EDR. motors refer to the "Explosion-Proof AC Motors" catalog.

Necessary information regarding the machine to be driven– Data of the application

Calculation of the relevant application data– Torque– Power– Regenerative power– Speeds– Overhung and axial loads– Travel diagram

↓ ↓

Drive selection– Selection of the gear unit type– Selection of the gear unit size and gear unit ratio– Checking the conditions of the typical application– Calculation of the motor terminal voltage only if the conditions of the typical application are

not fulfilled– Determination of the necessary motor speed based on the gear unit ratio and the neces-

sary control range. Maximum input speed = 1500 rpm For speeds > 1500 rpm, please con-tact SEW-EURODRIVE.

– Calculating the motor terminal voltage– Observe dynamic and thermal torque curves– Selection of the required motor size– Select a gearmotor combination using the selection tables for the appropriate unit catego-

ries– Necessary option: Motors must be fitted with a "TF" PTC temperature sensor.

↓

Selection of motor options– Brake– Encoder– Forced cooling fan

↓

Make sure that– the permitted overhung and axial loads are not exceeded– the limit speed of the motor is not exceeded

↓

Selecting the inverter– Observing the motor/inverter assignment– Continuous power and peak power in voltage-controlled inverters– Continuous current and peak current in current-controlled inverters– A braking resistor must always be selected, regardless of the duty type

↓

Options– Sinus filter– EMC measures– Communication


4 Project planning information – R, F, K, S, W gear unitsProject Planning

4.4 Project planning information – R, F, K, S, W gear units4.4.1 Efficiency of gear unitsGeneral informa-tion

The efficiency of gear units is mainly determined by the gearing and bearing friction.Keep in mind that the starting efficiency of a gear unit is always less than its efficiencyat operating speed. This factor is especially pronounced in the case of helical-worm andSPIROPLAN® right-angle gearmotors.

R, F, K gear units The efficiency of helical, parallel-shaft and helical-bevel gear units varies with the num-ber of gear stages, between 96 % (3-stage), 97 % (2-stage) and 98 % (1-stage).

S and W gear units The gearing in helical-worm and SPIROPLAN® gear units produces a high proportion ofsliding friction. As a result, these gear units have higher gearing losses than R, F or Kgear units and therefore lower efficiency.

The efficiency depends on the following factors:

• Gear ratio of the helical-worm or SPIROPLAN® stage

• Input speed

• Gear unit temperature

Helical-worm gear units from SEW-EURODRIVE are helical gear/worm combinationsthat are significantly more efficient than plain worm gear units.

The efficiency may reach η < 0.5 if the helical-worm gear stage has a very high gear ra-tio.

The SPIROPLAN® W37/W47 gear units from SEW-EURODRIVE have an efficiency ofmore than 90 %, which drops only slightly even for large gear unit ratios.

Self-locking Retrodriving torque in helical-worm or SPIROPLAN® gear units produces an efficiencyof η’ = 2 - 1/η, which is significantly less favorable than the forward efficiency η. The he-lical-worm or SPIROPLAN® gear unit is self-locking if the forward efficiency η is ≤ 0.5.Some SPIROPLAN® gear units are dynamically self-locking. Contact SEW-_EURODRIVE if you want to make technical use of the braking effect of self-lockingcharacteristics.

INFORMATIONNote that the self-locking effect of helical-worm or SPIROPLAN® gear units is not per-mitted as the sole safety function for hoists.


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Project planning information – R, F, K, S, W gear unitsProject Planning

Run-in phase The tooth flanks of new helical-worm and SPIROPLAN® gear units are not yet com-pletely smooth. This makes for a greater friction angle and less efficiency during the run-in phase than during later operation. This effect intensifies with increasing gear unit ratio.Subtract the following values from the listed efficiency during the running-in phase:

The run-in phase usually lasts 48 hours. Helical-worm and SPIROPLAN® gear unitsachieve their listed nominal efficiency values when:

• The gear unit has been completely run-in,

• The gear unit has reached nominal operating temperature,

• The recommended lubricant has been filled in, and

• The gear unit is operating in the rated load range.

Churning losses In certain gear unit mounting positions (see chapter "Gear Unit Mounting Positions"), thefirst gearing stage is completely immersed in the lubricant. When the circumferential ve-locity of the input stage is high, considerable churning losses occur in larger gear unitsthat must be taken into account. Contact SEW-EURODRIVE if you wish to use gearunits of this type.

To reduce churning losses to a minimum, use gear units in M1 mounting position.

Worm gear

i range η reduction

1-start About 50 – 280 About 12 %





SPIROPLAN® W..

i range η reduction

About 30 – 75 About 8 %





4.4.2 Oil expansion tank

The oil expansion tank allows the lubricant or air space of the gear unit to expand. Thismeans no lubricant can escape the breather valve at high operating temperatures.

SEW-EURODRIVE recommends to use oil expansion tanks for gear units and gearmo-tors in M4 mounting position and for input speeds > 2000 rpm.

The following figure shows the oil expansion tank.

The oil expansion tank is provided as assembly kit. It is intended for mounting onto thegearmotor. However, if installation space is limited or if the expansion tank is intendedfor gear units without motor, it can be mounted to nearby machine parts.

For further information, please contact your SEW-EURODRIVE sales representative.

4.4.3 Multi-stage gearmotorsGeneral informa-tion

You can achieve extremely low output speeds by using multi-stage gear units or multi-stage gearmotors. This means an additional second gear unit, usually a helical gear unit,is installed in front of the gear unit or between gear unit and motor.

The resulting total reduction ratio may make gear unit protection necessary.


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Limiting the motor power

You have to reduce the maximum output motor power according to the maximum per-mitted output torque on the gear unit (Ma max). For this purpose you first have to deter-mine the maximum permitted motor torque (MN zul).

You can calculate the maximum permitted motor torque as follows:

Use this maximum permitted motor torque MN zul and the load diagram of the motor todetermine the associated value for the motor current.

Take appropriate measures to prevent the continuous current consumption of the motorfrom exceeding the pre-determined value for the motor torque MN zul. An appropriatemeasure would be to set the trip current of the motor protection switch to this maximumcurrent value. A motor protection switch offers the option to compensate for a brief over-load, for example during the startup phase of the motor. A suitable measure for inverterdrives is to limit the output current of the inverter according to the determined motor cur-rent.

Checking brake torques

If you use a multi-stage brakemotor, you have to limit the braking torque (MB) accordingto the maximum permitted motor torque MN zul. The maximum permitted braking torqueis 200% MN zul.

MB max ≤ 200% MN zul

If you have questions on the starting frequency of multi-stage brake motors, please con-sult SEW-EURODRIVE.

Avoiding blockage

Blockage on the output side of the multi-stage gear unit or multi-stage gearmotor is notpermitted. The reason is that indeterminable torques and uncontrolled overhung andaxial loads may occur. The gear units may suffer irreparable damage as a result.

M =MN zul ηges

a maxi ges

INFORMATIONConsult SEW-EURODRIVE if blockages of the multi-stage gear unit or multi-stagegearmotor cannot be avoided due to the application.



4.4.4 Service factorDetermining the service factor

The effect of the driven machine on the gear unit is taken into account to a sufficient levelof accuracy using the service factor fB. The service factor is determined according to thedaily operating time and the starting frequency Z. Three load classifications are takeninto account depending on the mass acceleration factor. You can read the service factorapplicable to your application from figure 3. The service factor determined from this di-agram must be smaller than or equal to the service factor according to the selection ta-bles.

Load classification Three load classifications are distinguished:

* Daily operating time in hours/day** Starting frequency Z: The cycles include all starting and braking procedures as well as changeovers from

low to high speed and vice versa.

M f Ma B a× ≤ max

fB

0 200 400 600 800 1200 14001000

24* 16* 8*

0.8

0.9

1.0

1.1

1.2

1.3

1.4

1.5

1.6

1.0

1.1

1.2

1.3

1.4

1.5

1.6

1.7

1.2

1.3

1.4

1.5

1.6

1.7

1.8

Z [1/h] **

(III)

(II)

(I)

(I) Uniform, permitted mass acceleration factor ≤ 0.2(II) Non-uniform, permitted mass acceleration factor ≤ 3(III) Heavy shock load, permitted mass acceleration factor ≤ 10


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Mass acceleration factor

The mass acceleration factor is calculated as follows:

"All external mass moments of inertia" are the mass moments of inertia of the driven ma-chine and the gear unit, scaled down to the motor speed. The calculation for scalingdown to motor speed is performed using the following formula:

"Mass moment of inertia at the motor end" is the mass moment of inertia of the motorand, if installed, the brake and the flywheel fan (Z fan).

Service factors fB > 1.8 may occur with large mass acceleration factors (> 10), high lev-els of backlash in the transmission elements or large overhung loads. Contact SEW-EURODRIVE in such cases.

Servicefactor: SEW fB

The method for determining the maximum permitted continuous torque Mamax and usingthis value to derive the service factor fB = Mamax /Ma is not defined in a standard andvaries greatly from manufacturer to manufacturer. Even at a SEW service factor of fB =1, the gear units afford an extremely high level of safety and reliability in the fatiguestrength range (exception: wearing of the worm wheel in helical-worm gear units). Theservice factor may differ from specifications of other gear unit manufacturers. If you arein doubt, contact SEW-EURODRIVE for more detailed information on your specificdrive.

Example Mass acceleration factor 2.5 (load classification II), operating time 14 hours/day (readoff at 16 h/d) and 300 cycles/hour produce a service factor fB = 1.51 as shown in thefigure on the previous page. According to the selection tables, the selected gearedmotor must have an SEW fB value of 1.51 or greater.

Mass acceleration factor =All external mass moments of inertia

Mass moment of inertia at motor end

JXJnnM

= Mass moment of inertia scaled down to the motor shaft= Mass moment of inertia with reference to the output speed of the gear unit= Output speed of the gear unit= Motor speed

J Jn

nXM

= ×⎛

⎝⎜

⎞

⎠⎟2



Helical-worm gear units

Two further service factors have to be taken into account with helical-worm gear units inaddition to the service factor fB shown the above diagram. These are:

• fB1 = Service factor from ambient temperature

• fB2 = Service factor from cyclic duration factor

The additional service factors fB1 and fB2 can be determined by referring to the diagrambelow. For fB1, the load classification is taken into account in the same way as for fB.The following diagram shows the additional service factors fB1 and fB2:

Contact SEW-EURODRIVE in case of temperatures below -20 °C (→ fB1).

The total service factor for helical-worm gear units is calculated as follows:

Example The gearmotor with the service factor fB = 1.51 in the previous example is to be a helical-worm gearmotor.

Ambient temperature ϑ = 40 °C → fB1 = 1.38 (read off at load classification II)

Time under load = 40 min/h → cdf = 66.67 % → fB2 = 0.95

The total service factor is fBtot = 1.51 × 1.38 × 0.95 = 1.98

According to the selection tables, the selected helical-worm gearmotor must have anSEW fB service factor of 1.98 or greater.

4532296843

fB2

-20 0-10 20 40 6020 8030 100 %ED40 50°C

fB1

1.0 0.6

1.2 0.8

1.4 1.0

1.6

1.8

(III)

(II)

(I)

cdf Time under load in min/h%( )60

100= ×

f f f fBges B B B= × ×1 2


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4.4.5 Overhung and axial loadsPermitted overhung load

The basis for determining the permitted overhung loads is the computation of the ratedbearing service life L10h of the anti-friction bearings (according to ISO 281).

For special operating conditions, the permitted overhung loads can be determined withregard to the modified service life Lna on request.

On the input side: Overhung load conversion for off-center force application

Important: only applies to gear units with input shaft assembly:

Please contact SEW-EURODRIVE for off-center force application on the drive end.

INFORMATIONThe values refer to force applied to the center of the shaft end (in right-angle gearunits as viewed onto the drive end). The values for the force application angle αand direction of rotation are based on the most unfavorable conditions.

INFORMATIONReduction of overhung loads• Only 50% of the FRa value specified in the selection tables is permitted in mounting

position M1 with wall attachment on the front face for K and S gear units.• Helical-bevel gearmotors K167 and K187 in mounting positions M1 to M4: A maxi-

mum of 50% of the overhung load FRa specified in the selection tables in the caseof gear unit mounting other than as shown in the mounting position sheets.

• Foot or flange-mounted helical gearmotor (R..F): A maximum of 50 % of the over-hung load FRa specified in the selection tables for torque transmission via flangemounting are permitted.

Documents

4 Project Planning - download.sew-eurodrive.com · Usys System voltage, voltage of the supplying inverter V UBr Operating voltage of the brake V x Distance between overhung load application