How to Start your Large Motors- typical Solutions or new motor design?

How to start your large motors: typical
solutions or new motor design?
Delcho Penkov, Schneider Electric
Fredemar Runcos, WEG
Elder Stringari, WEG
Edouard Thibaut, TOTAL
Cécile Gaudeaux, Air Liquide

PCIC EUROPE2
Summary
• High power motors: typical applications & trends for Oil & Gas industry
• Why should we carefully consider the starting of such motors?
• How to optimize the start with typical solutions
• New trend in motor design may simplify the start
• Conclusions

PCIC EUROPE3
Scope of the tutorial
• MV Induction motors for pump and compressor applications
− running at constant speed
− operating in direct on-line connection to power system
− rated 2 000 kW and above

PCIC EUROPE4
• +90% of the electrical energy consumption
• +50% of the electrical equipment is used in motor feeders
• +50% of total motor feeder equipment cost could be the motor starting solution
(VSD, Soft-starter, autotransformer, etc..)
Motors are at the heart of the process
And a major design factor for the electrical installation

PCIC EUROPE5
High Power Motor Starting Challenge: fit the need!
• Objectives:
− Fit the application
− Cover eventual evolutions (so slightly oversize)
− Guarantee the operation
− Use approved solutions (which with time means
always the same)
• Consequences:
− Considers cumulative security margin
− May not be aware of the range effect and
prioritize one or another manufacturer
− May copy and paste proven solutions even
though not the most optimized
− May recommend high end solutions to keep
flexibility for evolutions
• Need:
− Reliable and safe equipment
− Easy to maintain by personnel on site
− Lowest possible cost
− Lowest footprint, to reduce collateral cost
− Easy to replace standard solutions for many
manufacturers
− Simple in principle
− Fitting right the need
− On time delivery
− Proven references
− Etc …
End User Designer
???

PCIC EUROPE6
Typical applications & trends of
High Power (HP) motors

PCIC EUROPE7
AC Motor technologies Power vs. Speed
3000 1500 1000 750 600 500 429 375 333 300 273 250
3600 1800 1200 900 720 600 514 450 400 360 327 300
MotorPower,kW
Induction machines
Synchronous
or
Induction machines
Synchronous machines
Speed, min-1
+90% of motors >2 000 kW are induction machines
Last 10 years growth

PCIC EUROPE8
Motor & control trends
Main drivers for going to large electrical
motors
• Easier control
• Lower maintenance cost
• High local energy generation
• Higher efficiency
• Lower footprint
• Greener
Main drivers for control simplification
• Reliability of operation
• Reduced footprint
• Low cost of local energy generation
DOL
VSD
80%
20%
Running Control
MV Motors sales volume
GO electric: Higher power electrical motors replace gas / steam turbine driven
machines
Keep it simple: Most motors are in DOL connection running at constant speed

PCIC EUROPE9
Oil & Gas Application Overview
Exploration & Production
Gas injection compressors
Water Injection Pumps
Transportation
Pipelines:
Gas Booster Compressors
Mainline Pumps
LNG:
Refrigerant Compressors
Boil off Compressors
Downstream
Refining:
H2 Make-up compressors
Petrochemicals:
PE/PP Extruders*
Syngas/CO2 Compressors
Air Separation:
Main Air Compressors
FLNG / FPSO
Subsea
Exploration
Pipeline
Refining
LNG
*In Bold are VSD only driven motors

PCIC EUROPE10
Constant Full Speed Motor Applications
Advantages
• CAPEX optimisation
• Simplicity of use and
maintenance
• Fits habits for use of mechanical
valves
Drawbacks
• Reduced efficiency at lower rate
• High starting current
• High mechanical stress at start
• Lower immunity to voltage drop
(compared to VSD driven motors)
Main compressor skid for an air separataion plant
Many applications run constantly on full speed: pumps, compressors, etc..

PCIC EUROPE11
Why to carefully consider the
starting of high power motors?

PCIC EUROPE12
What is a bad starting of a motor?
• Excessive voltage drop may cause parallel motors to loose stability
and disconnect or prevent motor to finish start
• Too long start would make the rotor to overheat and be replaced
• Repetitive high mechanical stress will develop mechanical faults
• Local generation may get overloaded due to wrong start-up solution
As a consequence, it will mean production losses,
unscheduled maintenance and high additional costs to get it
start well

PCIC EUROPE13
Case Study
• Utility: Scc = 3580 MVA
• Transformer: 50MVA
• Motor – 14 MW
• Different starting modes

PCIC EUROPE14
How to avoid bad motor starting?
• Consider the application characteristics
− Torque, values and shape
− Inertia
− Frequency of starts
• Verify motor characteristics
− Inrush current
− Torque, values and shape
− Available thermal capacity / starting time
• Analyse the electrical installation
− Available minimum short circuit power
− Initial conditions before start (voltage drop,
loading of transformer/generator)
Choose the right starting
solution:
•Voltage drop < 15-20%
•Motor heating
• < 90% seldom start
• < 80% frequent start
•Appropriate Motor design

PCIC EUROPE15
Basic Application parameters: load torque
• Constant torque – typically a volumetric pump / compressor ( typically with VSD)
• Linear torque – typically mixers (typically with VSD)
• Quadratic torque – typically centrifugal pumps, fans, compressors (?)
• Decreasing torque – not typical in Oil & Gas (crushers in mining)
Case study load torque during start

PCIC EUROPE16
motor_14mw_11kv _weg_JLeq3xJM.pl4: m:WPU
motor_14mw_11kv _weg_JLeqJM.pl4: m:WPU
motor_14mw_11kv _weg_JLeq2xJM.pl4: m:WPU
0 2 4 6 8 10[s]
0.00
0.22
0.44
0.66
0.88
1.10
[Wpu]
Basic Application parameters: load inertia
• The inertia is :
− dynamic load torque
− critical for selecting the
motor starting and control
− Responsible for motor
heating during start
3.6s
36% heating
5.2s
55% heating
6.6s
73% heating
Starting with same load with varying inertia
Motor speed evolution during start-up
Case study load torque during start

PCIC EUROPE17
Main parameters of an induction motor
• Motor Torque
− The torque is the force that provides acceleration capacity
• Power:
− Mechanical: it’s the result of Torque and Speed Pmech = T x w (T x ω)
− Electrical: Pelec = U x I x √3 x cosPhi
• Inertia –
− dynamic torque opposed to speed variation
• Efficiency: Pmech / Pelec
• Rated Speed
• Rated Voltage
• Rated Current
• Locked Rotor Current
• Locked Rotor Torque
• Locked Rotor Time
Example motor data

PCIC EUROPE18
0.0
1.0
2.0
3.0
4.0
5.0
6.0
0% 20% 40% 60% 80% 100% 120%
MotorCurrent,puofrated
Speed, % of rated
Average torque evolution of MV
induction motors during start
• Starting torque: 0.6 – 1.0 x rated
• Maximum torque: >1.5 – 2.5 x rated
0.0
0.5
1.0
1.5
2.0
2.5
0% 20% 40% 60% 80% 100% 120%
MotorTorque,puofrated
Speed, % of rated
Motor torque and current
Average current evolution of MV
induction motors during start
• Typical starting current : 5 - 7 x rated
• For high power motors 4-5 x rated
Acceleration torque
Load torque
LV Motor
MV Motor

PCIC EUROPE19
(f ile motor_14mw_11kv _dol_weg.pl4; x-v ar t) m:AVGV
0 3 6 9 12 15[s]
0.5
0.6
0.7
0.8
0.9
1.0
[Vpu]
• Voltage drop is created by the starting current
• It is factor of the minimum short-circuit power of the network
• Examples:
− 50 MVA transformer and grid, 10% Ucc Scc = 440 MVA 18% drop during start
− 50 MVA generator , 11kV, 15% Xd” Scc = 333 MVA 22% drop
− 50 MVA generator & 50 MVA step-up traf Scc = 200 MVA NO START
Basic constraints: Voltage drop
Voltage,pu
Voltage drop
Time, s

PCIC EUROPE20
Basic constraints: Mechanical stress
• Mechanical stress is generated by torque oscillations and vibration
• Frequent starting with high stress may contribute to:
− Loose foundation
− Bearings damage
• Some applications suffer sharp torque variations:
− Pumps : water hammer effect
− Fans: torsional impact due to higher inertia

PCIC EUROPE21
• Motor heating during start is estimated with I²t
formula
• During start the rotor heats much more than the
stator (rotor can reach 400-500°C)
• For each start the motor will heat at similar level
• Higher starting current means faster but shorter in
time heating
• Lower current means longer start and potentially
higher heating
• Harmonics also contribute to heating
Basic constraints: Motor heating
Selection of starting method shall account for the heating and the frequency of
starts required by the process

PCIC EUROPE22
Motor control methods overview (1)
Motor starting methods
Direct on Line (DOL) Autotransformer (RVAT)
Soft starter (RVSS) Low Inrush Current (LIC)
Motor starting and control
Variable Speed Drive (VSD)
Estimated volume of motor starting solutions

PCIC EUROPE23
Motor control methods overview (2)
Pony motorRotor resistances for
slip ring motors (WRIM)
Block Transformer (BTR) With reactor
HV
MV
M
M
M
w
High torque
Low starting current
Higher price
Periodic maintenance
Suitable for HP motors
No impact on // loads
High cost
Suitable for HP motors
Lower inrush current
Simple Pony to full speed
Higher cost

PCIC EUROPE24
Principle of operation
• Full line voltage is supplied sharply to the motor through contactor or circuit breaker
Main Characteristics
• High starting current and
starting torque
• High mechanical stress
Main applications
• Need of simple starting
solution
• Seldom starting of motors
• Systems with high short-
circuit power (as Oil & Gas)
Not recommended :
• In weak systems it will lead to
important voltage dip
• For frequently started motors it
will lead to premature ageing
due to the mechanical and
thermal stress at the rotor
Direct On-line Motor starting Method

PCIC EUROPE25
Typical Equipment
• Main advantages:
− Simple
− Low footprint
− Light
− Easy to commission
− Easy to install
• Main drawbacks:
− Limited number of
operations with CB
Indicative Volume ratio

PCIC EUROPE26
(f ile motor_14mw_11kv _dol_weg.pl4; x-v ar t) m:AVGV m:I_PU
0 3 6 9 12 15[s]
0.5
0.6
0.7
0.8
0.9
1.0
[Vpu]
0
1
2
3
4
5
6
[Ipu]
Simulation of case study: DOLVoltage,pu
Current,pu
Speed,pu
Torque,pu
Motor data:
Starting time: 5.2 s
Heating during start: 55%
Starting current: 5.3 x In
Simulation analyses:
Voltage drop: 19.5%
Effective Motor current: 4.2 x In
Starting time: 9 s
Motor heating: 65%
Starting is greatly affected by
voltage drop
(f ile motor_14mw_11kv _dol_weg.pl4; x-v ar t)
factors:
offsets:
1
0
m:T_PU
-1
0
m:WPU
1
0
0 3 6 9 12 15[s]
-1.5
-1.0
-0.5
0.0
0.5
1.0
1.5
2.0
[Tpu]
0.0
0.2
0.4
0.6
0.8
1.0
[Wpu]
Time, s
Time, s

PCIC EUROPE27
• Voltage is increased in steps through contactors connected to the secondary of the starting transformer
Main applications
• Pumps
• Compressors
Not recommended :
• For high inertia loads like fans
• For multi-motor starting
• For constant torque applications
Autotransformer Motor starting Method
• 40-60% of Starting torque
• 30-40% reduction of inrush
current
• Current and torque are
increased in steps
• High transient at every step
change
• Reduced mechanical stress
• Increased starting time

PCIC EUROPE28
RVAT Starting Sequence
First stage
CT1 close before CT2.
CT1 and CT2 are closed
CT3 is open
Second stage
CT1 is opened
CT2 remains closed
CT3 remains open
Third stage
CT3 is closed
CT2 remains closed
CT1 remains open
Stage 1
2
3

PCIC EUROPE29
Typical Equipment
• Autotransformer can be integrated in a cubicle or
stand alone
• Contactors or Circuit-Breakers are used as
interrupters
− Simple
− Harmonic free solution
− Very reliable
− Available at very high power range
• Main drawbacks:
− Very Heavy
− Large footprint solution (especially with CB)
− Limited flexibility and adaptation to spec
evolution

PCIC EUROPE30
(f ile motor_14mw_11kv _RVAT_weg.pl4; x-v ar t)
factors:
offsets:
1
0
m:T_PU
-1
0
m:WPU
1
0
0 4 8 12 16 20[s]
-1.0
-0.5
0.0
0.5
1.0
1.5
2.0
[Tpu]
0.0
0.2
0.4
0.6
0.8
1.0
[Wpu]
(f ile motor_14mw_11kv _RVAT_weg.pl4; x-v ar t) m:AVGV m:I_PU
0 4 8 12 16 20[s]
0.6
0.7
0.8
0.9
1.0
1.1
1.2
[Vpu]
0
1
2
3
4
5
[Ipu]
Simulation of case study: RVATVoltage,pu
Current,pu
Speed,pu
Torque,pu
Settings:
RVAT ratio: 80%
Prospective starting current: 4.2 x In
Voltage drop: 14.5%
Effective RVAT voltage: 70%
Motor heating: 84%
Starting parameters are affected by
voltage drop!
Accurate network data is necessary to
guarantee successfull start in the field
Time, s
Time, s

PCIC EUROPE31
• Current is limited electronically, by-passed with contactor at the end of start
Main applications
• In weak power systems
• For smooth acceleration / deceleration
• Pumps, fans, compressors
• Evolving applications
• Multi-motor starting
Not recommended :
• For constant torque
applications
Soft-Starter Method
• Current and voltage are
gradually increased
• Different starting profiles are
available
• Soft-stop of the motor
M
Protection and
Control Relay
Control Unit
Time
I limit
Ramp Limitation
Load CurrentInit
Full speed
Full Voltage
Initial
Voltage
Time
I, V
• (A) Line contactor
• (B) By-pass contactor
• (C) Silicon Controlled Rectifier (SCR)A
CB

PCIC EUROPE32
(f ile SOFT_STARTER_ref erence_conv entional.pl4; x-v ar t) v :V_UPA c:RVSSA -V_DWNA
70 74 78 82 86 90[ms]
-6000
-4000
-2000
0
2000
4000
6000
[V]
-700
-525
-350
-175
0
175
350
525
700
[A]
Thyristor based soft-starter
Zero-crossing
voltage Thyristor Firing
Firing delay α
Functionning principle
Voltage
Current

PCIC EUROPE33
Typical equipment
• Advantages
− Simple
− Low footprint
− Flexible
− 2-5 times lower cost than a VSD
− Insensitive to voltage drop
during start
− Smooths voltage drop (reduces
impact on generators)
• Drawbacks
− No true torque control
Single Soft-start
Multi-motor Soft-start
Line contactor
cubicle
By-pass
contactor
Power
electronics
modules
Incomer Soft-Starter
Motor 1 & 2

PCIC EUROPE34
(f ile motor_14mw_11kv _RVSS_weg.pl4; x-v ar t)
factors:
offsets:
1
0
m:T_PU
-1
0
m:WPU
1
0
0 4 8 12 16 20[s]
0.0
0.4
0.8
1.2
1.6
2.0
[Tpu]
0.0
0.2
0.4
0.6
0.8
1.0
[Wpu]
(f ile motor_14mw_11kv _RVSS_weg.pl4; x-v ar t) m:AVGV m:I_PU
0 4 8 12 16 20[s]
0.5
0.6
0.7
0.8
0.9
1.0
[Vpu]
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
[Ipu]
Simulation of case study: RVSSVoltage,pu
Current,pu
Speed,pu
Torque,pu
Settings:
Initial voltage: 40%
Voltage Ramp: 2 s
Current limitation: 3.6 x In
Voltage drop: 15%
Motor heating: 84%
Starting parameters not
affected by voltage drop
Time, s
Time, s

PCIC EUROPE35
• VSD vary the voltage and the frequency supplied to the motor
Main applications
• For any application
• For critical motors
• For process operation
• In limited capacity power
systems
Variable Speed Drive start and control
• Complete motor control during
operation and start
• Low thermal stress on start
• Suitable for very frequent starts
• Suitable for starting load driven
motors (conveyors)
• High cost of the solution if used
only for starting
Main features
• VSD converts AC power (50 Hz or 60
Hz) to DC and back to AC with a
variable frequency output (0 to 250
Hz)
• Varying the applied frequency allows
to control motor speed during start,
run and break phases
NPC converter
Multi-level converter

PCIC EUROPE36
MV VSD as Soft-Starter
Advantages
• No current impact on Power
supply during transfer
• No speed disturbance on
motor(process) during transfer
• VSD is sized lower than the motor
rating
• VSD avoids torque pulsations
VSD
Power supply
Electric Power
VSD

PCIC EUROPE37
Typical equipment
− Flexible solution
− Low fault current contribution in VSD
operation (1.5-1.75 x In)
− Allows to manage motor voltage and
optimize cost (motor and VSD)
− Starting at lowest motor current (< 1 x In)
• Main drawbacks:
− Long commissioning time
− Heavy and bulky
− Complicated on-site mounting for large
drives
− Sensible to humidity and dust
− Complex parameter set-up

PCIC EUROPE38
(f ile 14MW_grid_VC_VFby pass_f in_trans18_test2_DPV.pl4; x-v ar t)
factors:
offsets:
1
0
m:T_PU
-1
0
m:WPU
1
0
0 5 10 15 20 25[s]
0.00
0.15
0.30
0.45
0.60
0.75
0.90
[Tpu]
0.0
0.2
0.4
0.6
0.8
1.0
[Wpu](f ile 14MW_grid_VC_VFby pass_f in_trans18_test2_DPV.pl4; x-v ar t) m:AVGV m:I_PU
0 5 10 15 20 25[s]
0.5
0.6
0.7
0.8
0.9
1.0
[Vpu]
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
[Ipu]
Simulation of case study: VSD as Soft-StarterVoltage,pu
NetworkCurrent,pu
Speed,pu
Torque,pu
Voltage drop: < 5%
VSD input current: < 1.15 x In
Starting time: 20 s
Motor heating: <2%
Acceleration in
vector control
Phase
lock
VSD
Disconnection
Output
switch
open
By-pass
switch
close
Time, s
Time, s
Switch to
V/F control

PCIC EUROPE39
• Motor is designed with lower inrush current, 3 – 4 x In
• Conventional DOL start
Main applications
• For pumps, fans,
compressors
• For high power motors
• For seldom started motors
• In limited capacity power
systems
Low Inrush Current Motor
• Start torque is lower
• Maximum torque is reduced
• Start current is reduced
• Voltage drop is reduced
• Start time is increased
• Motor cost is slightly
increased
Not recommended
• For frequently started motors
due to higher heating
• May be unstable against
important voltage fluctuations

PCIC EUROPE40 (f ile Motor_14MW_11kV_LIC3_DOL_WEG.pl4; x-v ar t)
factors:
offsets:
1
0
m:T_PU
-1
0
m:WPU
1
0
0 4 8 12 16 20[s]
-1.0
-0.5
0.0
0.5
1.0
1.5
[Tpu]
0.0
0.2
0.4
0.6
0.8
1.0
[Wpu]
(f ile Motor_14MW_11kV_LIC3_DOL_WEG.pl4; x-v ar t) m:AVGV m:I_PU
0 4 8 12 16 20[s]
0.5
0.6
0.7
0.8
0.9
1.0
[Vpu]
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
[Ipu]
Simulation of case study: DOL LIC motorVoltage,pu
Current,pu
Speed,pu
Torque,pu
Motor data:
Heating during start: 55%
Starting current: 3 x In
Locked Rotor time: 15s
Breakdown torque: 150%
Voltage drop: 12.7%
Motor current: 2.6 x In
Starting time: 14 s
Motor heating: 66%
Breakdown torque: 115%
• Motor torque is relatively low during start
• Parallel LIC motors may loose stability for
20% voltage drop in normal operation
• Parallel overloaded LIC motors may loose
stability even at 15% drop
Time, s
Time, s

PCIC EUROPE41
Design of Low Inrush Current
Motor

PCIC EUROPE42
Low Inrush Current Induction Motor Design
Characteristics of a Squirrel Cage Induction Motor:
1- High Performance;
2- Robust solution;
3- Low maintenance;
4- Cost effective
The challenge to design
Low Inrush Current [LIC] Motor
is to keep the same
characteristics

PCIC EUROPE43
LIC Motor typical load applications:
1- Two or Four pole motor;
2- Centrifugal pumps or compressors – Parabolic load torque curve;
3- Load inertia less than motor inertia;
0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
1.10
1.20
1.30
1.40
1.50
1.60
1.70
1.80
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
1.60
1.80
2.00
2.20
2.40
2.60
2.80
3.00
3.20
3.40
3.60
Torque at 100% Voltage
Load Toque
Currente at 100% Voltage
Load Torque Curve and Motor Torque and Current Curves
Speed in [pu]
Torquein[pu]
Currentin[pu]
Motor Torque
Motor Starting Current
Parabolic Load Torque Curve

PCIC EUROPE44
Typical LIC Motor Performance Requirements:
1- Locked rotor current (LRC) →( 3,0 to 4,0 )pu - No positive tolerance
2- Locked rotor torque (LRT) → (0,25 to 0,35)pu - No negative tolerance
3- Break Down torque (BDT) → 1,50 pu - No negative tolerance
4- Efficiency → Higher than 96%
5- Power Factor → Higher than 88%
6- Transient voltage drop in steady state condition (-15%);

PCIC EUROPE45
What is main End User CONCERN?
All values offered
should be attended
in final test

PCIC EUROPE46
How to Achieve LIC Motor Performance Requirements?
 Designer expertise;
 Accurate electromagnetic design program;
 A finely controlled manufacturing process;

PCIC EUROPE47
Design solutions of a LIC Motor
The design solutions to obtain a low inrush current induction motor are not new.
Nevertheless, the solutions affect strongly the motor performance, like:
 Starting inrush current;
 Starting torque;
 Breakdown torque;
 Efficiency;
 Power factor;
The difficulty to achieve a good solution is proportional to the
specifications constraints.

PCIC EUROPE48
Stator Electromagnetic Design Characteristics:
1.Reduced magnetic flux;
2.Minimized magnetic circuit saturation;
3.Optimized leakage reactance;

PCIC EUROPE49
Rotor Electromagnetic Design Characteristics:
1. Decisive contribution to reduce the starting inrush current;
2. Proper choice of bar and short circuit ring materials
conductivity and of course the cross-sections
Material
[kg/m3] [S/m] [1/K] [J/kgK]
Copper 8,90 58 0,00393 394
Brass.9505 8,85 32,3 0,00219 385
Brass.8515 8,75 21,5 0,00146 380
Brass.6436 8,47 15,0 0,00102 377

PCIC EUROPE50
Rotor Eletromagnetic Design Characteristics:
1. Optimized skin effect on the rotor bar and short circuit ring impedance;
2. Minimezed magnetic circuit saturation;
3. Optimized leakage reactance;

PCIC EUROPE51
Break Down or Excess Torque
LIC induction motors affects strongly the BDT
2
Non
LRC
1 2
I
U
I k
X X
 
  
 
2
Non
BDT
1 2
T
U
T k
X X
 
  
 
Physically is very hard to achieve 150% of BDT with LRC lower than 300%;
PhysicalLimit
LIC

PCIC EUROPE52
Break Down or Excess Torque – Voltage Drop Simulation
A
C
B
A: Starting motor with load curve at 100% of voltage
B: Time instant of full load at motor is applied;
C: Time instant of voltage drop of -15% during 4.5s
Reliable operation up to
voltage drop of -15%

PCIC EUROPE53
RELIABILITY OF CALCULATION AND MANUFACTURING PROCESS
The natural question that rises:
How reliable are the
calculations results with the
manufacturing process?
To answer this question it is necessary to analyze the
physical properties of the conductor and the magnetic
material use in the electromagnetic design of the motor.

PCIC EUROPE54
CONDUCTORS:
The physical properties of
Stator and Rotor
conductors are not affected
during the manufacturing
process
MAGNETIC MATERIAL:
Magnetic Material
Properties – Permeability-
Suface Insulation –Specific
Losses

PCIC EUROPE55
MANUFACTURING
PROCESS:
Stamping process –
Burr grades – Heat
treatment
CORE ASSEMBLY:
Pressure – Core Fixation

PCIC EUROPE56
To avoid changes in the magnetic
circuit, and consequently changes in
the reactances: mX
Tight Process Control
Must be Implemented
1X 2X

PCIC EUROPE57
1 - To design a LIC induction motor is
necessary to consider in a deep detail the
physical properties of the stator and rotor
circuit conductors and the magnetic properties
of the lamination core of the motor.
2- The reliability of the designed values is
strictly related with:
 Designer expertise;
 Accurate electromagnetic design software;
 A well controlled manufacturing process.

PCIC EUROPE58
Difference:
LIC ≠ DOL
 Weight : +10%
 Inertia: +10%
 Cost: + (10 to 20%)
 Power factor: - (1 to 3%)
 Efficiency: - (0,10 to 0,5%)
 Footprint: same

PCIC EUROPE60
Motor starting and protection
• General guidelines
Starting /
Control
type
Network impact Motor & Load
impact
Protection Starting
current
Fault current peak
contribution
DOL
Standard
Voltage drop,
lower power
factor
Strong mechanical
stress, vibrations
By relay 5-6 x In 5-6 x In
RVAT Reduced voltage
drop, lower
power factor
Reduced mechanical
and electrical stress
RVSS As RVAT Very much reduced
mechanical and
electrical stress
LIC As RVAT As RVAT By relay 3-4 x In 3-4 x In
VSD No Ideal solution By VSD 1-1.5 x In 1-1.5 x In
(VSD permanent)

PCIC EUROPE61
Comparison of technical/economical aspects
• General guidelines (more smiles means better)
Starting /
Control type
Economical
interest
OPEX
savings
Engineering
simplicity
Maintenance
easiness
Footprint Weight Flexibility of
adaptation
DOL Standard ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺
RVAT ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺
RVSS ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺
LIC ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺
VSD ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺

PCIC EUROPE62
Comparative analyses from case study
Starting
solution
Relative cost Relative weight
Relative
footprint
Effective
start Current
Voltage
drop
Heating
DOL Std 100% 100% 100% 4.2 x In 19.5% 65%
DOL LIC 110-120% 110% 100% 2.6 x In 12.7% 66%
RVAT 600% 600 - 1000% 600% 3.5 x In 14.5% 84%
RVSS 400% 300 - 400% 400% 3.6 x In 15% 84%
VSD > 2 000% 1000 – 2 000 % > 2 000% 1.15 x In <5% <2%

PCIC EUROPE63
Motor Control Methods ranking
DOL
VSD
CaPex
ED Network Impact
Low
(Istart/Inom<1.5)
Medium
(Istart/Inom<4)
High
(Istart/Inom>6)
HighMediumLow
RVAT RVSSLIC
WRIM
BTR
Pony
Reactor
DOL: Direct on line
RVAT: Reduced Voltage Auto-transformer
RVSS: Reduced Voltage Soft-Start
VSD: Variable Speed Drive
LIC: Low Inrush Current motor
BTR: Block transformer
Reactor: Through limiting reactor
Pony: Pony motor
WRIM: Wound Rotor Induction Machine

PCIC EUROPE64
How to Start High Power Motors?

How to Start your Large Motors- typical Solutions or new motor design?

Recommandé

Recommandé

Contenu connexe

Tendances

Tendances (20)

Similaire à How to Start your Large Motors- typical Solutions or new motor design?

Similaire à How to Start your Large Motors- typical Solutions or new motor design? (20)

Dernier

Dernier (20)

How to Start your Large Motors- typical Solutions or new motor design?