vfd sizing

ACS800 Learning Guide Drive dimensioning for cranes

mech

L0cont.hoist ηω

vg)m(m T⋅

⋅⋅+=

( ) ( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛⎟⎠⎞⎜

⎝⎛⋅+⋅++⋅=

2

L0mech

othmacc

acc ωvmm

η1JJ

tω T

ABB

ACS800 - Drive dimensioning for cranes

Rev 1.0.EN Sheet 2 ABB 17 April 2008 N° of sh 65

Frequency converters ACS800 with Direct Torque Control can easily be used on demanding applications as cranes. In this document we give some hints for selecting motors and drives, taking into account some specific requirements on hoists and travel motions. We consider as well new overhead traveling cranes as refurbishing jobs. When using this document, actual drives and motors performances and compatibility must be checked with supplier’s latest information. Feedback and comments about this dimensioning document can be sent to: [email protected]@fi.abb.com Frans Busschots, BE-ABB Rev 1.0.EN

mailto:[email protected]

mailto:[email protected]


Rev 1.0.EN Sheet 3

• Dimensioning theory – motor basics • Crane basics • Motor choice, ACS800 Drive and brake resistor sizing • Example

• Tools

ABB 17 April 2008 N° of sh 65



Content (1) Sheet 1 Introduction 8 2 General condition of a dimensioning procedure 10 3 Induction motor (AC) fundamentals

3.1 Torque / speed diagram with direct on line start 11 3.2 Torque / speed diagram with frequency converter 12 3.3 Maximum motor torque with frequency converter 13 3.4 Continuous motor torque with inverter 13

3.5 Rated motor torque / maximum motor torque 14 3.6 Relation power and torque 16 3.7 Relation power and torque: example 17 3.8 Operation in four quadrants (hoist) 18 3.9 Operation in four quadrants (long and cross travel) 19 3.10 Duty factor uprating 21 3.11 Duty factor uprating: example 22 3.12 Motor derating with ACS 800 and standard motors 23 3.13 Motor ambient conditions 24 3.14 Maximum motor speed 25 3.15 Motor with reinforced insulation and/or insulated N-bearing 26 3.16 Motor in DELTA connection at 87 Hz (230 V/ 400V) 27 3.17 Motors 400 V / 690 V 29



Content (2) Sheet 4 Crane basics

4.1 Hoist 30 4.1.1 Torque and power needed to hoist a load at constant speed 4.1.2 Torque needed to lower a load at constant speed 4.1.3 Torque and power needed to accelerate/ decelerate a load 4.1.4 Total torque needed on a hoist drive

4.1.5 Maximum power needed on a hoist drive 4.1.6 Maximum braking power needed on a hoist drive

4.2 Gantry/trolley travel – Long/cross travel 34

4.2.1 Torque and power needed to move a crane at constant speed 4.2.2 Acceleration torque from 0 to maximum speed 4.2.3 Maximum torque needed on a travel drive 4.2.4 Maximum power needed on a travel drive

4.2.5 Total braking torque/power needed on a travel drive

5 Particular cases 37 5.1 Motors in parallel 6 Motor choice 41 6.1 Hoist 6.2 Travel motions



Content (3) 7 Drive sizing Hoist and travel 43

7.1 Drive module 7.2 Brake chopper / resistor sizing for a hoist 7.2.1 Continuous braking power 7.2.2 Peak braking power 7.3 Brake chopper / resistor sizing for travel motions 7.3.1 Travel indoors

7.3.2 Travel outdoors with wind 7.4 Brake chopper sizing 7.5 Brake resistor sizing 7.6 Regenerative drive 7.7 Common DC-Bus 8 Redundant drives 51 9 Crane refurbishing 52 9.1 Total revamp 9.2 Partial revamp 9.3 Dimensioning replacement drives 9.3.1 Replacing DC-motors

9.3.2 Slipring motors

10 Crane Control 56 11 Examples (draft) 57 11.1 Hoist 11.2 Travel



Content (4) 12 Examples Motor and drive choice 62 13 Tools 65 13.1 Excel sheet for hoist 13.2 Excel sheet for travel


Rev 1.0.EN Sheet 8

1 Introduction

E.O.T. Crane

Electrical Overhead Traveling Crane

Capacity typical 10 – 350 Tons Mostly used indoors Frequently used in power plants / paper and metals industry / waste handling



Rev 1.0.EN Sheet 9

1 Introduction An E.O.T. Crane has 3 motions: Hoist: hook up and down Cross travel (= short travel): trolley movement Long travel (= crane travel): gantry movement Sometimes there is an auxiliary hoist on a second trolley for tilting purposes, or an auxiliary hook to handle smaller loads at higher speed Some cranes have 2 identical hooks on 2 separate trolleys to handle long products or a special hook with master/follower in synchro control




2 General condition of a dimensioning procedure

1. Check the initial conditions of the network and the load

2. Choose a motor according to:

a. thermal loadability

b. speed range

c. maximum needed torque

3. Choose a drive according to

a. continuous and maximum current

b. network conditions

c. braking requirements


Rev 1.0.EN Sheet 11

3 Induction (AC) motor fundamentals 3.1 Torque / speed diagram with direct on line start

Maximum torque Thermally dimensioned working point



3 Induction (AC) motor fundamentals 3.2 Torque / speed diagram with frequency converter

Power Rated motor torqueMax mot Torque x 0,7

250

200

150

100

50

0 0 1

%

Motor flux depend

From 0 Hz to rated

If V/H

Above rated motorvoltage and can no

So V/

Motor

ABB

V/Hz constant

0 20 30 40 50

Frequen

s on V/Hz ratio:

motor frequency (typical 50

z ratio is kept constant, fluxMotor torque is constant Motor power goes up with in

frequency (typical 50 Hz), st be increased to follow the i

Hz ratio will diminish, and (field weakening) torque decreases with incr

V constant field weakening

Rev 1.0.EN Sheet 12

100 60 70 80 90

cy (Hz)

Hz), V/Hz ratio can be kept constant

is constant

creasing speed

upply voltage normally corresponds to rated motor ncreasing frequency:

flux goes down with increasing freq.

easing freq, power is constant in this range

17 April 2008 N° of sh 65


3 Induction (AC) motor fundamentals 3.3 Maximum motor torque with a frequency converter: 3.3.1 Below nominal frequency (typically 0 to 50 Hz): To have a safety margin, the maximum design torque should be 70% of maximum torque TMAX Design = 0.7 x TMAX /TN

Typical values for TMAX /TN for squirrel cage motors: 2.5 to 3.0

3.3.2 In field weakening area (typically 50 Hz to FMAX): Maximum motor torque decreases with the square of the frequency ratio: TMAX = TMAX 50 Hz /TN x (50 Hz / FMAX )² maximum design torque should be only 70 %: TMAX Design = 0.7 x TMAX /TN x (50 Hz / FMAX )² e.g. at 100 Hz: TMAX Design = 0.7 x TMAX /TN x 1/4

At double frequency, maximum torque is divided by four!!!!

3.4 Continuous motor torque with a frequency converter: see 3.12 Motor derating



Rev 1.0.EN Sheet 14

3 Induction (AC) motor fundamentals

3.5 Rated motor torque / maximum motor torque

3.5.1 Motor catalogue

Motor M3BP 280 SMB P: 90 kW Speed: 1483 rpm Tn = Nominal (rated) torque: 580 Nm Maximum torque (also called breakdown torque): TMAX/TN = 2.7 , so TMAX 580 x 2.7 Nm = 1566 Nm



Rev 1.0.EN Sheet 15


3.5.2 Below nominal frequency (0 to typically 50 Hz): maximum design torque should be T = 0.7 x TMAX / TN T = 580 x 2.7 x 0.7 = 1096 Nm 3.5.3 Above nominal frequency (50 Hz to ....Hz): e.g. at 100 Hz : T = 0.7 x TMAX /TN x (50 Hz / 100 Hz)2 = 0.7 x 580 x 2.7 / 4 Nm T = 274 Nm In the field weakening range, the motor power is expected te be constant, but the maximum available motor torque will be the limiting factor!!

Motor rated power is 90 kw BUT: maximum available torque is only 274 Nm, Maximum motor power: P = T x n / 9550 = 274 x 3000 / 9550 = 86 kW, overload included (instead 90 kW with 150% overload in heavy duty)


0

50

100

150

200

250

0 10 20 30 40 50 60 70 80 90 100

Frequency

PowerRated motor torqueMaximum Motor Torque x 0,7

290 Nm (90 kW)

274 Nm (86 kW)


Rev 1.0.EN Sheet 16

3 Induction (AC) motor fundamentals 3.6 Relation power and torque

Relation Power – Torque (on same shaft):

NmPTω

= with = 602π

*n (rad/s)

Nmn

PT 9550*=

Or:

NmnTP9550

*= P = T * ω Important note: always consider torque and power on “same shaft”, e.g. after a gearbox torque can be enormous at very low speed

Definitions: F Force (N) P Power (w) T Torque (Nm) v Velocity of the load (m/s) Efficiency Angular velocity (rad/s) n Motor shaft speed (rpm)



Rev 1.0.EN Sheet 17


3.7 Relation power and torque: example

motor M3BP 315 SMC-6, 110 kW, 991 rpm

rated torque: Nmn

PT = = n9550* Nm

9919550*110

= 1060 Nm



Rev 1.0.EN Sheet 18


3.8 Operation in four quadrants (hoist)

Speed

Acc I Dec IIUp

Down Time Acc III Dec IV

T

IV IDeceleration when lowering Acceleration when hoisting

Braking Driving

n II III

Driving Braking Acceleration when lowering Deceleration when hoisting

With a suspended load on the hook, braking is also necessary during a normal lowering of the load at steady speed !!!

Maximum braking torque is needed at the end of the lowering!



Rev 1.0.EN Sheet 19


3.9 Operation in four quadrants (long and cross travel)

3.9.1 Travel movement without wind

Speed

Acc I Dec IIForward

Backwards Time Acc III Dec IV

T

Deceleration backwards

IV I Acceleration forwards

Braking Driving

n III II

Driving Braking Acceleration backwards Deceleration forwards

Only braking power needed during deceleration (forwards and backwards)




3.9.2 Travel movement with wind

When wind is blowing in opposite direction as the crane is moving, a lot of

pressure can be built up on the crane surface (e.g. 250 Nm/m²!!): this effect gives an extra load torque: acceleration will be more difficult!!

The wind torque can drive the crane by itself: after releasing the brakes the full motor torque must be immediately available to prevent the crane rushing in the wrong direction (safety !!)

When wind is blowing in the same direction as the crane is moving, the wind torque can drive the crane by itself: after releasing the brakes the full motor torque must be immediately available to prevent the crane to go in overspeed (safety !!)

(The situation can be compared with a hoist during lowering!)

Maximum braking torque is needed to stop the crane.

Attention when using braking resistors: a lot of energy must be evacuated

during total travelling time, not only at stopping the crane

At maximum wind force (above the safe working limit), it must be possible to drive the crane to a safety position where the crane can be mechanically blocked to the rails.



Rev 1.0.EN Sheet 21


3.10 Duty factor uprating On a crane not all motors are fully loaded all time. During a time lapse at no load or at standstill, the motor temperature can cool down, so the average temperature will be lower as compared to a motor that runs at full load continuously (S1). In some cases a smaller motor can be chosen, but don’t forget too take into consideration that there is less cooling at low speed. See next pages. The duty cycle can be very different for the different crane movements. E.g. After a hoist movement to pick up a load the crane must travel to another point before the load will be lowered.

Important note: Duty factor uprating concerns only motor temperature rise, a smaller motor has a lower breakdown torque: to be checked!!

The table below (ABB motors) can be different for different motor manufacturers.

Intermittent duty, S3 Poles

56-100 112-250 280-45015% 2 115 145 140

4 140 145 1406 - 8 140 140 140

25% 2 110 130 1304 130 130 130

6 - 8 135 125 13040% 2 110 110 120

4 120 110 1206 - 8 125 108 120

60% 2 105 107 1104 110 107 110

6 - 8 115 105 110

Permitted output as % of rated output in S1for motor size: (ABB)



Rev 1.0.EN Sheet 22

3 Induction (AC) motor fundamentals 3.11 Duty factor uprating: example Continuous motor power needed, based on the dimensioning calculation: 48 kW, 1480 rpm Normal motor choice: 55 kW But, hoist motion Duty Factor is estimated: S3 60% We can check the smaller motor: M3BP 225SMC-4, 45 kW In the table on page 20 we find the “Uprating factor” for shaft height 225: 107% so motor M3BP 225SMB-4, 45 kW can be used for 45 x 1.07 = 48.15 kW No need to use bigger motor.

Intermittent duty, S3 Poles

56-100 280-45015% 2 115 145 140

4 140 145 1406 - 8 140 140 140

25% 2 110 130 1304 130 130 130

6 - 8 135 125 13040% 2 110 110 120

4 120 110 1206 - 8 125 108 120

2 105 1104 110 107 110

6 - 8 115 105 110

Permitted output as % of rated output in S1

for motor size:112-250

60% 107

107 %



Rev 1.0.EN Sheet 23


3.12 Motor derating with ACS 800 and standard motors T/Tn


Important notes:

Don’t choose lowest point of speed range at ZERO speed: Every crane starts at ZERO speed, but normally the lowest speed is only used for a short time. A hoist is a constant torque application, so, if zero speed is chosen as a working point, the derating result will be exaggerated. ADVICE: try to estimate the average motor speed during a cycle and consider also the duty cycle as shown on page 20.

If not specified by the end-user and when ambient temperature is normal, class F temperature rise can be used.

But don’t forget: a motor winding temperature increase of 10K will divide expected lifetime by factor 2

110% 100% 90% 80% 70% 60% 50% 40%

0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 Relative speed

Separate cooling

Class F temperature rise used for Class B motor

Temperature rise Class B


Rev 1.0.EN Sheet 24

3 Induction (AC) motor fundamentals 3.13 Motor ambient conditions Normal rules about ambient motor conditions must be considered. EOT cranes can be in very difficult situation:

always close to the roof: heat built up sometimes above furnaces or hot coil or slabs: heat radiation moisture and dirt in metallurgy: avoid dirt in cooling air

Ambient temperature °C

Permitted output% of rated output

30 10740 10045 96,550 9355 9060 86,570 7980 70

Height above see levelm

Permitted output% of rated output

1000 1001500 962000 922500 883000 843500 804000 76




3 Induction (AC) motor fundamentals 3.14 Maximum motor speed

When a motor is connected to a drive, the output frequency can be set above 50 Hz (field

weakening area) As seen on page XXX the maximum available motor torque decreases sharply, but also

mechanical factors must be considered when using motors above rated speed: - centrifugal forces on the rotor - bearing lubrication - noise of motor fan (when no forced ventilation is used)

The table below indicates max. motor speed for standard motors without special arrangements, for all individual cases the motor manufacturer must be consulted. Frame Size ABB motor Max speed (rpm)

80 - 90 - 100 6000 112 - 132 - 160 -200 4500

225 - 250 -280 3600 315 (2p) 3600

315 (4-12p) 3000 355 - 400 (2p) 3600

355 - 400 (4-12p) 2500


Rev 1.0.EN Sheet 26

3 Induction (AC) motor fundamentals 3.15 Motor with reinforced insulation and/or insulated N-bearing

Motor nominal power PN or frame sizePN < 100 kW PN ≥ 100 kW or PN ≥ 350 kW or

≥ IEC 315 ≥ IEC 400UN ≤ 500 V Standard motor Standard motor Standard motor

+ Insulated N-bearing + Insulated N-bearing+ Common mode filter

UN ≤ 600 V Standard motor Standard motor Standard motor+ dU/dt - filter + dU/dt – filter + Insulated N-bearing

+ Insulated N-bearing + dU/dt -filterOR OR + Common mode filterReinforced insulation Reinforced insulation OR

+ Insulated N-bearing Reinforced insulation+ Insulated N-bearing+ Common mode filter

UN ≤ 690 V Reinforced insulation Reinforced insulation Reinforced insulation+ dU/dt - filter + dU/dt - filter + Insulated N-bearing

+ Insulated N-bearing + dU/dt -filter+ Common mode filter

Motor nominal power PN or frame sizePN < 100 kW PN ≥ 100 kW or PN ≥ 350 kW or

≥ IEC 315 ≥ IEC 400UN ≤ 500 V Standard motor Standard motor Standard motor

+ Insulated N-bearing + Insulated N-bearing+ Common mode filter

UN ≤ 600 V Standard motor Standard motor Standard motor+ dU/dt - filter + dU/dt – filter + Insulated N-bearing

+ Insulated N-bearing + dU/dt -filterOR OR + Common mode filterReinforced insulation Reinforced insulation OR

+ Insulated N-bearing Reinforced insulation+ Insulated N-bearing+ Common mode filter

UN ≤ 690 V Reinforced insulation Reinforced insulation Reinforced insulation+ dU/dt - filter + dU/dt - filter + Insulated N-bearing

+ Insulated N-bearing + dU/dt -filter+ Common mode filter



Rev 1.0.EN Sheet 27


3.16 Motor in DELTA connection at 87 Hz (230 V/ 400V) A 3 phase motor designed 230 V/400 V, 50 Hz has all six leads connected to a terminal box. Y or ∆: depends on line voltage available Y : for line supply 3 x 400 V, 50 Hz ∆ : for line supply 3 x 230 V, 50 Hz In ∆ configuration the V/Hz ratio is 230/50. When we connect this motor to a drive with supply voltage 230V, field weakening starts around 50 Hz. But if we connect this motor to a drive with supply voltage 400V, field weakening starts around 87 Hz, what means that between 50 and 87 Hz this motor can deliver the same torque as below 50Hz.

Motor 400V, 87 Hz, D

0

50

100

150

200

250

300

350

400

0 10 20 30 40 50 60 70 80 90 100

Frequency

Volta

ge

Power Rated motor torque Motor voltage

87 Hz corresponds with 400V

50 Hz corresponds with 230V




Summary: old rating plate new rating plate Nominal voltage 3 x 400 V, Y 3 x 400 V, ∆ Nominal frequency 50 Hz 87 Hz Nominal current 11,5 A 20 A Nominal power 11 kW 19 kW Nominal speed 2930 rpm 5125 rpm

With same torque at higher speed, the motor can deliver more power.

Important remarks: 1.When changing the connection from Y to ∆, the motor current is multiplied with 1.73, so a

bigger drive is needed!! (corresponding to the new motor power) 2.ID-run parameters in group 99 of the drive must be filled in with the old rating plate data (at 50

Hz). The drive calculates automatically the new field weakening point related to the available DC-voltage.



Rev 1.0.EN Sheet 29


3.17 Motor 400 V / 690 V Motor nameplate:

When supply voltage is 400 V, this motor must be connected in ∆ and it is not possible to use this motor at 87 Hz with constant flux When supply voltage is 690 V, this motor can be connected in Y for normal use: with constant flux till 50 Hz and above 50 Hz in field weakening area: with constant power OR: The motor can be connected in ∆ and when supplied by an ACS800 at 690V with constant flux to 87 Hz. Motor power will be 11 kW x 1.73 = 19 kW Speed: synchronous speed: 3000 rpm x 1.73 = 5190 rpm Slip: same (constant flux): 3000 rpm – 2930 rpm = 70 rpm Real rated motor speed: 5190 rpm – 70 rpm = 5120 rpm

Not 2930 rpm x 1.73 = 5069 rpm, as slip don’t increase!



4 Crane basics 4.1 Hoist

4.1.1 Torque and power needed to hoist a load at constant speed Nm (I)


or

mech

L0cont.hoist ηω

vg)m(m T⋅

⋅⋅

Watt

+=

mech

L0cont.hoist η

g)m(m ⋅+=

v P ⋅

Definitions: m0 Mass of the lifting system (rope/hook..) which is hoisted with load (kg) mL Mass of the load (kg) + ? overload (see local conditions) g Gravity (9.81 m/s2) v Hoist motion velocity (m/s) η

mech Mechanical efficiency (typical 0.9) n Motor speed (rpm)

)/(60

n2π ω srad⋅=


Rev 1.0.EN Sheet 31

Speed

Tcont hoist I

Up

Down Time Tcont low. IV

4 Crane basics

4.1.2 Torque needed to lower a load at constant speed

Nm (IV)


or Watt

ωvgη)m(m T mechL0

cont.lower⋅⋅⋅+

=

mechL0cont.lower ηv)m- ⋅⋅ g(m P ⋅

This is the continuous braking power !!

+=

Definitions: m0 Mass of the lifting system (rope/hook..) which is hoisted with load (kg) mL Mass of the load (kg) + ? overload (see local conditions) g Gravity (9.81 m/s2) v Hoist motion velocity (m/s) ηmech Mechanical efficiency (typical 0.9) n Motor speed (rpm)


Rev 1.0.EN Sheet 32

Crane basics

4.1.3 Torque during acceleration and deceleration Acceleration torque from 0 to maximum speed (hoisting and lowering):


Nm (I-III)

( ) ( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛⎟⎠⎞⎜

⎝⎛⋅+⋅++=

2

L0mech

othmacc

acc ωvmm

η1JJ T ⋅

tω

Nm (II-IV)

( ) ( ) ⎟⎟⎠

⎞

⎝

⎛⎟⎠⎞⎜

⎝⎛⋅+⋅++=

2

L0mechothmdec

dec ωvmmηJJω T ⎜

⎜⋅t

Speed

Time

Up Dec II Acc I

Down Acc III Dec IV

Definitions: m0 Mass of the lifting system (rope/hook..) )/(

60n2π ω srad⋅=

which is hoisted with load (kg) mL Mass of the load (kg) + ? overload (see local conditions) g Gravity (9.81 m/s2) v Hoist motion velocity (m/s) ηmech Mechanical efficiency (typical 0.9) tacc Acceleration (sec) tdec Deceleration (sec) (ramp) time (ramp) time Jm Motor moment (kgm2) Joth Inertia for other (kgm2) of inertia rotating parts reduced to motor n Motor speed (rpm) shaft


Rev 1.0.EN Sheet 33

4 Crane basics

4.1.4 Total torque needed on a hoist drive TMax = Tcont.hoist + Tacc (4.1.1 and 4.1.3) If the deceleration time is shorter then the acceleration time, it is possible that Tdec > Tacc Then TMax = Tcont.hoist + Tdec (4.1.1 and 4.1.3) Maximum braking torque TMax braking = Tcont.lower + Tdec (4.1.2 and 4.1.3)

Check if fast stop or emergency stop ramp is required! (Braking distance!) 4.1.5 Maximum power needed on a hoist drive

kW9550

n*TP MaxMax = n: motor speed (rpm)

4.1.6 Maximum braking power needed on a hoist drive

kW9550

n*TP brakingMax brakingMax =



4 Crane basics 4.2 Gantry/trolley travel – Long/cross travel

4.2.1 Torque and power needed to move a crane at constant speed

(friction)

4.2.1.1 Torque due to rolling friction: Nm

( )

mech

fL0

f ηω

vwmm

4.2.1.2 Torque due to wind Nm

⋅

⋅⋅+= T

T Wind force is given by the wind velocity and the wind area: with W = 250 N/m² at wind speed 20 m/s

mechw ηω

Wv ⋅⋅=

N 6.1

windwind

v² * A W =

Definitions: m0 Weight of the crane part which is moved with the gantry (kg) mL Mass of the load (kg) + ? overload (see local conditions) wf Friction coefficient (N/kg) v Gantry velocity (m/s) W Wind force (N) Awind Wind area (m2) n Motor speed (rpm)

Wheel diameter (mm) 250 315 400 500 >500

Wheel friction

)/(60

n2π ω srad⋅=


0 07 0 065 0 06 0 055 0 05


Rev 1.0.EN Sheet 35

4 Crane basics (4.2 Gantry/Trolley travel) 4.2.1.3 Total continuous torque (thermal motor load) Tcont = Tf + Tw (rolling friction + wind) 4.2.2 Acceleration/deceleration torque from 0 to maximum speed

( ) ( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛⎟⎠⎞⎜

⎝⎛⋅+⋅++⋅=

2

L0mech

othmacc

acc ωvmm

η1JJ

tω T

( ) ( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛⎟⎠⎞⎜

⎝⎛⋅+⋅++⋅=

2

L0mechothmdec

dec ωvmmηJJ

tω T

Definitions: m0 Mass of the crane / trolley which is moved with the load (kg) mL Mass of the load (kg) + ? overload (see local conditions) v Crane / trolley motion velocity (m/s) ηmech Mechanical efficiency (typical 0.9) i Gear ratio

tacc Acceleration (sec) )/(60

n2π ω srad⋅=

(ramp) time tdec Deceleration (sec) (ramp) time Jm Motor moment (kgm2) n motor speed (rpm) of inertia Joth Inertia for other (kgm2)



4 Crane basics

4.2.3 Maximum torque needed on a travel drive during acceleration TMax = Tf + Tw + Tacc (4.2.1.1; 4.2.1.2; 4.2.2) If the deceleration time is shorter then the acceleration time, it is possible that Tdec > Tacc Then check if deceleration with wind in same direction is worst case? TMax = Tdec + Tw - Tf (4.2.1.1; 4.2.1.2; 4.2.2) 4.2.4 Maximum power needed on a travel drive

kW9550

n*TP MaxMax = n: motor speed (rpm)

4.2.5 Total braking torque/power needed on a travel drive 4.2.5.1 Without wind forces Tbraking = Tdec - Tf (4.2.1.1; 4.2.2) (only during deceleration time) 4.2.5.2 With wind forces during travel in same direction as wind Tbraking = Tw (4.2.2) (contiously during travel in same direction as wind) 4.2.5.3 Peak braking power at end of travel in same direction as wind TPeak braking = Tdec + Tw - Tf (4.2.1.1; 4.2.1.2; 4.2.2) (peak only during deceleration time)



Rev 1.0.EN Sheet 37

5 Particular cases 5.1 Motors in parallel All gantry drives and most trolley drives have multimotor configuration. As all this motors are mechanically connected (over the rail) and their load is more or less identical, these motors can be connected as a group to ONE drive or in different groups to more drives in master/slave connection. 5.1.1 Motor dimensioning All basic torque and power calculations on previous pages remain valid, but don’t forget to add all motors and couplings inertia together. Finally the needed torque can be divided by the number off motors installed BUT: always check for the worst case scenario E.g. gantry drive: When the trolley is moved to extreme left or right position on the crane, the weight of the trolley and the load will be very asymmetrical for the gantry motors. This can be seen when comparing the reaction forces on the gantry wheels (info from crane maufacturer)


E.g. gantry weight : 100 ton, trolley 30 ton, load 40 ton Equally distributed load: left side 50 + 35 ton – right side 50 + 35 ton: 85 – 85 ton Trolley left position: 80 % of trolley + load extra to the left side: 50 + 56 ton load to the right side: 50 + 14 ton: 106 – 56 ton So 25 % more load on motors M1 and M3 The motor choice (max. torque) must be based on this “worst case” load

M1

Short travel

M4 M3

M2

Rail A Rail B Long travel Long travel

M1

Short travel

M4 M3

M2

Rail A Rail B



5 Particular cases 5.1.2 Drive dimensioning 5.1.2.1 One single drive When only 1 drive will feed all motors, the current absorbed by each motor will be related to the (electrical) slip of this motor (slip is related to the load). When some motors are loaded less because load is asymmetrical, the other motors will be loaded less, so total current will be the same as presumed in the calculations. Extra hint: When connecting motors in parallel to 1 drive, always consider the sum of the maximum motor currents to choose the appropriate drive and never motor powers, as the sum of the magnetizing currents of a number of smaller motors is bigger than for 1 bigger motor. (These effect increases with increasing motor pole pairs.) E.g. 4 pcs motors M3BP 225 SMB-8, 22 kW, 730 rpm, 400 V, 45 A. Total current 4 * 45 A = 180 A Compared to a motor M3BP 315 SMC-8, 90 kW, 741 rpm, 400 V, 167 A. Motor powers mentioned in the drive catalogue normally refer to 4p motors: Motor M3BP 280 SMB-4, 90 kW, 1483 rpm, 400 V, 159 A so 13% difference


Rev 1.0.EN Sheet 39

5.1.2.2 Drives in Master/Slave connection For each group of motors the “worst case” scenario must be considered: When connecting all motors from one side of the gantry together (M1-M3 and M2-M4), load can be asymmetrical and drives must be upgraded accordingly. Not only the position of the cross travel, but also the structure of the crane can give different load.


When connecting the motors in the front and in the back of the gantry together (M1-M2 and M3-M4), there is no influence from the trolley position, only the crane structure can cause a (permanent) load difference. Master alone can also move the crane. Attention for braking distance.

M1

Short travel

M4 M3

M2

Rail A Rail B

M1

Long travel

Short travel

M4 M3

M2

Rail A Rail B Long travel


Rev 1.0.EN Sheet 40

5.1.2.2 Drives in Master/Slave connection (continuation) For a good load distribution, a cross connection left/right – front/back can also be used Disadvantage: no speed correction left/right possible


Short travel

M4M3

M1 M2

Rail A Rail B Long travel


6 Motor choice 6.1 Hoist 6.1.1 Thermal motor load Needed continuous motor torque T: see sh 30 (4.1.1) Corrections with: duty factor (uprating) sh 21 (3.10) speed range (derating) sh 23 (3.12) ambient conditions sh 24 (3.13) Continuous motor torque at rated speed: continuous motor power

NmnTP9550

*= Motor can be chosen in motor catalogue. For a hoist the cont. motor torque is normally the most demanding criterion, but check always the maximum needed motor torque 6.1.2 Maximum motor torque Needed maximum torque: sh 33 (4.1.4) Corrections with: maximum design torque sh 13 (3.3)

Attention: Once a motor is chosen, all calculations where (estimated) motor inertia is used (acceleration torque!!) most be reconsidered with the exact inertia

6.1.3 Real motor data: Check motor rated current Calculate motor current corresponding to max. motor torque needed. Consider some saturation effect above rated motor torque (10% e.g.)



6.2 Travel motions 6.2.1 Maximum motor torque Maximum motor torque T needed: see page 36 (4.2.3) Choose motor according this maximum torque, taking into account the maximum design torque: sh 13 (3.3)

Attention: Once a motor is chosen, all calculations where (estimated) motor inertia is used (acceleration torque!!) most be reconsidered with the real motor inertia

For a travel motion (indoor) the maximum torque is normally the most demanding criterion, but checks always the continuous motor power needed. For outdoor cranes the wind load can be considerable, dimensioning with the data for the thermal load are on sh 35: continuous motor torque (4.2.1.3) Continuous motor torque at rated speed: continuous motor power

NmnTP9550

*= Motor can be chosen in motor catalogue. 6.2.2 Real motor data: Check motor rated current Calculate motor current corresponding to max. motor torque needed. Consider some saturation effect (10% e.g.)



Rev 1.0.EN Sheet 43

7 Drive sizing hoist and travel 7.1 Drive module Choose drive ACS800 according the motor power in “heavy duty use” (6.3)


“heavy duty use”means: Maximum drive current during 1 min is 150% of rated HD current.

If max. motor torque needed > 150% (travel!!) a bigger drive must be chosen Max. current needed / 1.5 < I hd (6.3)


Rev 1.0.EN Sheet 44

7 Drive sizing 7.2 Brake chopper / resistor sizing for a hoist


7.2.1 Continuous braking power:

Duty cycle:

- time for lowering: max. hoisting height / load speed (s) pause: - time for hoisting: max. hoisting height / load speed (s) - time for connecting/disconnecting load to be added to cycle time

Remark: if braking continues over 30 seconds, braking is considered continuous and not intermitted.

7.2.2 Peak braking power At the end of a lowering cycle the deceleration power must be added to the continuous power

due to gravity, but this power also decreases at decreasing speed.

kW9550

n*TP brakingMax brakingMax = (4.16)

BrakingPower

Time Lowering

Speed

Hoisting

Up

Down


Rev 1.0.EN Sheet 45

7 Drive sizing 7.3 Brake chopper / resistor sizing for travel


7.3.1 Travel indoors

BrakingPower

Speed

Left Dec

De c Right Time

Duty cycle:

- deceleration time left + deceleration time right pause: - time for traveling left and right - time for connecting/disconnecting load to be added to cycle time (no load)

Braking power decrease with decreasing speed: triangular load with short duty cycle


Rev 1.0.EN Sheet 46

7 Drive sizing 7.3.2 Travel outdoors with wind

BrakingPower

Speed


Duty cycle:

- time for traveling left + deceleration time right + deceleration time left pause: - time for traveling right - time for connecting/disconnecting load to be added to cycle time

Braking power is continuous during travel with wind in the back if wind torque is bigger as the resistive torque: the length of the track will be determining the braking resistor capacity.

Time

Wind Wind in back in front

Left Dec

De cRight


Rev 1.0.EN Sheet 47

7 Drive sizing 7.4 Brake chopper sizing: Capacity of internal braking chopper (option code +D150) must be checked: (certainly for frames R2 and R3 where the internal braking chopper is standard in all drives.) Pbrcont = Phd . (30 seconds) Max. continuous braking torque < continuous Pbrcont


If internal chopper is too small:

- external braking chopper must be added - or a bigger drive can be chosen with higher Pbrcont


Rev 1.0.EN Sheet 48

7 Drive sizing 7.5 Brake resistor sizing: Parameters to define a braking resistor:

1. Peakpower that the resistor must be able to absorb:

R²UP

DCmax <

UDC : voltage over resistor during braking = 1.35*UAC *1.2 (1.2: chopper starting voltage) R: resistor value in ohms: a too high value will limit braking power!

Remark: lowest resistor value allowed on brake chopper as mentioned in table (R)



Rev 1.0.EN Sheet 49

7 Drive sizing

2.Power than can be dissipated by heat transfer to the air, taking into account a cycle time, Or: continuous power capacity intermittent power capacity The power capacity of standard resistors in ABB drive table (sheet 48) is normally to small for hoist applications and travel with wind. In order too boost capacity with same resistance value 4 resistors can be put in series / parallel to obtain four times thermal capacity.


Also other combinations are possible or resistors can be purchased from other manufactures, as long as the minimum resistor value is respected.

R R

RRRR =



7 Drive sizing 7.6 Regenerative drive 7.7 Common DC-Bus



8 Redundant drives 8.1 For each drive 1 extra drive: full redundant solution. For very critical installations where interruptions in the process can not be allowed, an extra drive can be installed for fast switch-over. 8.2 One drive as back-up for 2 drives with similar kVA. A drive can have 2 parameter sets, so a redundant drive can be switched between 2 movements. E.g. between main and auxiliary hoist, or between long and cross travel 8.3 No extra drives installed but switching between movements for alternative movements of the crane.


9 Crane refurbishing The metal structure of a crane has a longer lifetime as the electric and electronic components, so after some years a crane can be modernized. 9.1 Total revamp: All motors/drives will be replaced 9.2 Partial revamp:

In case of existing AC slipring or AC squirrel cage motors, these motors can sometimes be re-used after cleaning and/or adaptations. New drives will be added.

9.3 Dimensioning replacement drives Motor and drive dimensioning is the same as shown in previous pages, but often it is difficult

to find the old files with the original design criteria. In that case the dimensioning must be based on the specifications of the existing motors and drives.

9.3.1 Replacing DC-motors

Try to find out what was max. overload allowed: 160% or 200% (?) and check field weakening range, this can be higher than allowed for AC motors. Motor base speed is normally not a standard synchronous speed.

Important remark: 9.3.1.1 When choosing an AC motor with higher base speed, motor power must be extra derated accordingly the speed difference. 9.3.1.2 When choosing an AC motor with lower base speed, motor power is constant in the field weakening area, but then max. speed must be checked. 9.3.1.3 DC-motors can have a wide field-weaking range. When replacing by AC-solution, don’t forget the limitations by the maximum motor torque at higher frequencies. 3.2.2 (sh 12)



Rev 1.0.EN Sheet 53

9 Crane refurbishing 9.3.2 Slipring motors Some basic information: Slipring motors can have high pull-out torque compared to squirrel cage motors. This is never mentioned on the motor rating plate. Other places where this data can be found:

motor manufacturer (motor serial number!) original motor catalogue from date of purchase of the motor original file about the crane (delivered by crane manufacturer, often kept in the

mechanical maintenance department TMAX /TN : 4-5.5 is possible


Table ABB HXS slipring motors:


Rev

9 Crane refurbishing 9.3.2 Slipring motors Some basic information (continuing): By changing rotor resistance maximum torque is available from start to rated speed

T

R2E

TL4 3 2 1

n nsn0

This high starting torque is not well controlled.conditions e.g.) the crane moves not gently but

Important remark:

1. Slip ring motors are typically rotor critical anarea 70-100 % of rated speed. With a drive the critical from loadability point of view 2. The choice of a slipring motor was normallytaking into account:

duty cycle

the number of starts per hour: everythe actual load. This current causes

resistance x ( current )²

ABB 17 A

Definitions: T Motor torque TL Load torque n Motor speed nSn Rated synchronous speedR2E External rotor resistance 1-4 Load points

1.0.EN Sheet 54

When nearly no torque is needed (at no load whit shocks at start.

d originally designed for speed control in the peed range goes to 0%. But lower speeds are

based on the thermal load of the motor,

start causes an inrush current independent from heat:

pril 2008 N° of sh 65



9 Crane refurbishing 9.3.2 Slipring motors Some basic information (continuing):

after choosing a motor a final check was made to see if the maximum motor

torque of this motor was sufficient also for the worst case in the working cycle: e.g. starting torque with full load against the wind!

2 situations possible:

1. maximum motor torque is too small: a bigger motor will be chosen 2. maximum motor torque is sufficient: motor choice is OK,

but the full motor torque will never be needed

After e.g. 25 years it will be very difficult to find out the real need. An oversized motor and drive will not cause problems for the crane behavior as the motor torque will be adapted by the drive to the real need. Only

When connecting slipring motors to a drive, the rotor circuit must be short-circuited:

external in connection box but: slipring and brushes remain in service and continue to wear

internally on rotor itself motor must be opened and rotor must be dynamically rebalanced

on a hoist drive: encoder must be added on motor shaft

when re-using existing motors the use of du/dt filters is recommended to decrease the voltage stress on the motor insulation


Rev 1.0.EN Sheet 56

9 Crane Control ACS 800

(more doc to follow)

DC linkRectifier

V1 V3 V5

V2V6V4

C

L +

-

U1V1W1

M 3 ~Ud

Control Electronicscontrol, monitoring and communication

L1

L2

L3

InverterMotor

Supply

DC linkRectifier

V1 V3 V5

V2V6V4

C

L +

-

U1V1W1

M 3 ~M 3 ~Ud

Control Electronicscontrol, monitoring and communication

L1

L2

L3

InverterMotor

Supply

Uline UDC UoutUline UDC Uout

encoder speed

brake ctrl

ACS800-Crane Control 0x

RMIO motor and application ctrl

PLC fieldbus

PC

ethernet ,internet

stand-alone I/O

brake resistor

follower control , DDCS



Rev 1.0.EN Sheet 57

11 Examples (draft) 11.1 Hoist

11.1.1 Torque and power needed to hoist a load at constant speed


= 882 Nm 0,929102,6 ⋅

or = 90 600 Watt

0,4179,819800780 ⋅⋅+= )( Tcont.hoist

0,92919800)(780 ⋅0,4179,81⋅+= Pcont.hoist

Values: m0 780 (kg) mL 18 000 (kg) + overload 10% = 19 800 kg g 9.81 m/s2

v 25 m/min= 0.417 (m/s) ηmech 0.929

11.1.2 Torque needed to lower a load at constant speed

= 762 Nm

102,60,4179,810,92920000)(580 ⋅⋅⋅+= cont.lower T

or = -78 210 Watt

102.660

8092 π ω =⋅=

0;9290,4179,8120000)(580- ⋅⋅⋅+= Pcont.lower Continuous braking power during lowering: 78.2 kW


11 Examples (draft) 11.1.3 Torque and power needed to accelerate/ decelerate a load Acceleration torque from 0 to maximum speed (hoisting and lowering):

= 413 Nm

⎟⎟⎠⎝

= 410 Nm

⎟⎠

⎞⎞⎜⎛2

102.60.417

⎟⎟⎠

⎟⎠

⎞⎞⎜⎝⎛⋅

2

102.60.417

102.660

980π =⋅

( )

⎜⎛T

⎜⎝⋅⋅+⋅= 20580

0.92917.44

1.94102.6 acc

( )

7.44T

Definitions: m0 780 kg mL 18 000 (kg) + overload 10%= 19 800 kg g 9.81 m/s2

v 25 m/min= 0.417 (m/s) ηmech 0.929 i Gear ratio tacc 1.94 (sec) tdec 1.94 (sec) Jm 4.1 kgm2 Joth 3.34 kgm2

⎜⎜⎝

⎛⋅+⋅= 20580929.0

1.94102.6 dec

2 ω =


11.1.4 Total torque needed on a hoist drive TMax = 882 Nm + 413 Nm = 1295 Nm 11.1.5 Maximum power needed on a hoist drive

kW9550

980*1295P Max = = 133 kW


11 Examples (draft) Maximum braking torque TMax braking = 762 Nm + 410 Nm (4.1.2 and 4.1.3)

11.1.6 Maximum braking power needed on a hoist drive

kW9550

980*1172P brakingMax =

P Max braking = 120.3 kW



Rev 1.0.EN Sheet 60

11 Examples (draft)

11.2 Gantry travel 4.2.1 Torque and power needed to move a crane at constant speed (friction)

4.2.1.1 Steady state torque, due to rolling friction:


Values: m0 59 000 kg mL 20 000 kg wf 0.05 N/kg v 1.67 m/s W 25 000 N Wheel diameter 710 mm number of motors: 2

Wheel diameter (mm) 250 315 400 500 >500

Wheel friction Wf (N/kg) 0,07 0,065 0,06 0,055 0,05

Nm

( ) 44 Tf 4.2.1.2 Torque due to wind Nm

0.961551.670.0579000 =

⋅⋅⋅=

401 0.96155

002511.67 w =⋅⋅=

1556014802 π ω =⋅=

T


Rev 1.0.EN Sheet 61

11 Examples (draft)

11.2.2 Acceleration/deceleration torque from 0 to maximum speed

( ) ( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛⎟⎠⎞⎜

⎝⎛⋅⋅+⋅=

2

1551.6779000

0.9610.11

5.5155 Tacc

( ) ( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛⎟⎠⎞⎜

⎝⎛⋅+⋅++⋅=

2

L0mechothmdec

dec ωvmmηJJ

tω T

Values:

m0 59 000 kg mL 20 000 kg v 1.67 m/s ηmech 0.96 tacc 5.6 sec tdec 5.6 sec Jm 0.05 kgm2

Joth 0.06 kgm2

number of motors: 2

1556014802 π ω =⋅=




12 Examples: motor and drive choice

12.1.1 Thermal motor load Needed continuous motor torque: hoist: 882 Nm (4.1.1) travel: sh 25 (4.2.1.1) or (4.2.1.2) corrections with: duty factor (uprating) 60%: 1.07 (10.9) speed range (derating) average speed 50%: 0.95 (3.10) ambient conditions 40°C: 1 (3.11) corrected motor torque: 882 Nm / 1.07 /0.95 / 1 = 868 Nm P= M*N/9550= 868 * 980 / 9550 = 89 kW Motor choice: 90 kW, 992 rpm, 866 Nm, 163 A, Tmax/Tn 2.8 12.1.2 Maximum motor torque hoist: 1295 Nm (4.1.4) Available on chosen motor: 866 *2.8*0.7=1697 Nm OK travel: sh 27 (4.2.3) 12.1.3 Final motor choice: M3BP 315 SMB6, 90 kW, 992 rpm, 400V, 163A, 866 Nm, 4.1 kgm² motor current corresponding to max. motor torque needed : 163 *1295 / 866= 243 A



12 Examples: motor and drive choice 12.2.1 Single drive choice Choose drive ACS800 according the motor power in “heavy duty use” (6.3) 90 kw HD : ACS800-01-0135-3 (R6), 163 A Max current 1 min/ 5 min: 163A *1.5 = 244 A This is very close to what is calculated. Taking into account some current saturation effect in the motor, better choice is next module: 110 kw HD : ACS800-01-0165-3 (R6), 215 A Max current 1 min/ 5 min: 215A *1.5 = 244 A Braking chopper in module: PBrcont = 132 kW , minimum resistance: 2.7 ohm



12 Examples: motor and drive choice 12.2.2 Brake chopper / resistor sizing Braking cycle needed: Hook path: 15 m, speed: 25 m/min, max. cycle: 25 sec total cycle time estimated: 60 sec Cont. braking power needed during lowering with short peak at end of lowering: 85 kW This corresponds with a resistor 44 kW permanent use. Braking capacity for standard resistor: 13.5 kW cont not sufficient, but OK when connecting 4 pcs in series parallel (same total resistance, power times 4)


Rev 1.0.EN Sheet 65

13 Tools Excel sheet to convert mechanical crane data to motor torque and power needed 13.1 Excel sheet for hoist:

Drive: Levage 70 TLoad/Motor speed: 5 m/min 720 RPM Drum diameter: 560 mm

Hoisting speed: 5 m/min 750 RPM Number of ropes: 2Nominal load: 68,0 tons Gear ratio 1:

+empty mass: 2,0 tons Vmax: 4,7 m/min Mechanical efficiency: 85 % Total load: 70,0 tons Motor inertia 5,000 kgm^2 +overload: tons External inertia/motor 2,000 kgm^2 Max. load: 70,0 tons Total inertia/motor 7,07 kgm^2

CALCULATED POWER & TORQUE REQUIREMENTS: MOTOR DATA:No load (at Vmax): 1,8 kW = 23,0 Nm Static Number of poles: 8

Nominal load: 63,1 kW = 803,6 Nm -"- Nominal frequency: 50 HzMax. load : 63,1 kW = 803,6 Nm -"- Number of motors: 1

Nom. load acceleration: 85,0 kW = 1081,7 Nm Dynamic Max. Frequency: 50 HzMax. load acceleration: 85,0 kW = 1081,7 Nm -"- Nmax: 750 RPM

acceleration: 21,8 kW = 278,1 Nm -"- Acceleration time: 2,00 sec.Overload: kW = Nm Static TLmax/Tnrl: 1,35

Acceleration time 0-max: 2,00 sec.

13.2 Excel sheet for travel

Drive: ChariotTravel speed/Mot. speed: 30 m/min 1000 RPM Wheel diameter: 400 mm

Travelling speed: 30 m/min 1000 RPMWeight of load+hook: 21,50 tons Gear ratio 1: 263,19

Weight of gantry/trolley: 13,8 tons Vmax: 30,0 m/min Mechanical efficiency: 85 % Total mass: 35,3 tons Motor inertia 0,10 kgm^2

Rolling friction: 50 N/ton External inertia/motor 0,05 kgm^2Wind force: kN Inclination: ° Total inertia/motor 0,95 kgm^2

CALCULATED POWER & TORQUE REQUIREMENTS: MOTOR DATA:No load (at Vmax): 0,4 kW = 3,9 Nm Static Number of poles: 6

Nominal load: 1,0 kW = 9,9 Nm -"- Nominal frequency: 50 HzMax. load(wind etc.) : 1,0 kW = 9,9 Nm -"- Number of motors: 1

Nom. load acceleration: 5,0 kW = 48,2 Nm Dynamic Max. Frequency: 50 HzMax. load acceleration: 5,0 kW = 48,2 Nm -"- Nmax: 1000 RPM

acceleration: 4,0 kW = 38,3 Nm -"- Acceleration time: 3,00 sec.Wind etc. load: kW = Nm Static TLmax/Tnrl: 4,86

Acceleration time 0-max: 3,00 sec.


vfd sizing

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