Danfoss Electronics VLT Soft Starter Pocket Guide
Pocket Guide
VLT® Soft Starter
– the single speed drive
Contents
Soft Starter Selection Guide
Warnings .................................................................................................................................... 5
Common Applications .......................................................................................................... 6
MCD Soft Starter Features and Specications ............................................................. 8
Current Ratings ........................................................................................................................11
Soft Starter Sizing ................................................................................................................. 13
FAQs
Adaptive Acceleration Control ......................................................................................... 14
AC53 Utilisation Codes ...................................................................................................... 15
Auto-Transformer Starters ............................................................................................... 16
Fault nding ............................................................................................................................. 16
Braking ....................................................................................................................................... 17
Bypass Contactor ................................................................................................................. 18
Cabling ..................................................................................................................................... 19
Extreme Conditions ............................................................................................................ 21
Flying Loads ........................................................................................................................... 22
Harmonics .............................................................................................................................. 22
IP Ratings ................................................................................................................................ 23
NEMA Ratings ........................................................................................................................ 24
Inside delta Connection .....................................................................................................25
Key Benets ........................................................................................................................... 26
Line Contac tor ...................................................................................................................... 27
Minimum Start Current ..................................................................................................... 28
Multiple Motors .................................................................................................................... 29
Power factor correction .................................................................................................... 30
Motor Thermal Capacity ................................................................................................... 30
Jog ............................................................................................................................................... 31
Reversing ................................................................................................................................ 31
Sealed Enclosures ................................................................................................................ 32
Primary Resistance Starters ............................................................................................. 32
Short Circuit Protection, Type 1 ...................................................................................... 33
Short Circuit Protection, Type 2 .......................................................................................34
Semiconductor Fuse Selection, Type 2 ........................................................................ 35
Slip-Ring Motors .................................................................................................................. 38
Soft Braking ........................................................................................................................... 39
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Star/Delta Starters ............................................................................................................... 40
Thermal Model Protection ............................................................................................... 42
Two Speed Motors .............................................................................................................. 43
Types of Soft Starter ........................................................................................................... 44
MCD Bus Options
MCD Bus Options – General Notes ................................................................................ 45
MCD 500 with MCD Remote Operator Option .......................................................... 46
MCD 500 Modbus Option ................................................................................................. 48
MCD 500 DeviceNet Option ............................................................................................. 49
MCD 500 PROFIBUS Option .............................................................................................. 50
MCD 500 USB Option ........................................................................................................... 51
MCD 200 with MCD Remote Operator Option .......................................................... 52
MCD 200 Modbus Option .................................................................................................. 53
MCD 200 DeviceNet Option .............................................................................................. 55
MCD 200 Probus Option .................................................................................................. 56
MCD 200 USB Option ........................................................................................................... 57
Glossary
Glossar y ....................................................................................................................................58
Abbreviations .........................................................................................................................63
4 | Danfoss Drives · DKDD.PB.551.A1.02
Warnings
Soft starter selection requires information on the
intended application, the features required, and
the curre nt rating of the associated motor.
For applications with extreme or unusual conditions, consult the
relevant Design Guide and/or your supplier.
For example:
• High altitude installation (> 1000 m)
• High ambient temperatures (> 40˚ C)
• High and/or frequent operating overloads
• High start frequency
• Slip-ring motor operation
• Part speed operation
• Horizontal mounting of the starter
Danfoss Drives · DKDD.PB.551.A1.02 | 5
Common Applications
This table lists common applications for soft starters, and their
nominal duty ratings.
Application Normal Heavy Severe
Agitator •
Auger •
Blower (axial fan) •
Bottle Washer •
Centrifuge •
Chipper •
Compressor, centrifugal (rotary) •
Compressor (reciprocating, unloaded) •
Compressor (screw, unloaded) •
Conveyor (loaded) •
Conveyor (unloaded) •
Crusher, cone •
Crusher, jaw •
Crusher, rotary (unloaded) •
Debarker •
Drilling machine •
Dust collector •
Edger •
Escalator •
Fan, centrifugal (damped) •
Fan, centrifugal (undamped) •
Grinder •
Hydraulic power pack •
Mill, ball •
Mill, hammer •
Mill, roller •
Milliscreen •
6 | Danfoss Drives · DKDD.PB.551.A1.02
Application Normal Heavy Severe
Mixer (low viscosity) •
Mixer (high viscosity) •
Pelletiser •
Planer •
Press •
Pump, bore •
Pump, centrifugal •
Pump, positive displacement •
Pump, slurry •
Pump, submersible •
Pump, vacuum •
Re-pulper •
Rotary table •
Sander •
Saw, band •
Saw, circular •
Shredder •
Separator, liquids •
Separator, solids •
Slabber •
Slicer •
Travelato r •
Tumbler/Dryer •
Vibrating screen •
Winch •
Wire draw machine (hydraulic) •
Danfoss Drives · DKDD.PB.551.A1.02 | 7
MCD Soft Starter Features and Specications
MCD 500
• Soft start: Current limit, Current
ramp, Kickstart, AAC Adaptive
Acceleration Control
• Soft stop: Timed voltage ramp,
AAC Adaptive Control, DC brake
• Motor protection: Motor connection, Power loss, Phase loss, Mains
frequency, Current imbalance,
Motor thermistor, Motor overload
• System protection:
Phase sequence, Excess start time,
Undercurrent, Instantaneous
overcurrent, Bypass relay overload,
Heatsink temperature
• Metering: Current, Motor
temperature, Motor kW, motor kVA,
Motor pf
• Control option: Local control
panel plus remote inputs/outputs.
Dedicated output for MCD LCP 501
• Network communication: options
for DeviceNet, Modbus, PROFIBUS
and USB
• Bypass:
7.5 ~ 500 kW internally bypassed;
630 ~ 800 kW dedicated terminals
for external bypass connection
MCD 500
• Current: 7.5 kW ~ 800 kW @400 V
• Mains voltage: 200 ~ 690 VAC
• Supply frequency: 50/60 Hz
• Enclosure: 7.5 ~ 55 kW IP 20,
60 ~ 800 kW IP 00
Control Panel VLT® LCP 501
• Same user interface as
VLT® Soft Starter MCD 500
• Plug & play with MCD 500
• Copy/ paste of parameters
• Multiple monitoring setup
• Door-mount kit – 3 m cable
• IP 65 (NEMA 12)
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MCD 2 01
• Soft start/stop:
Timed voltage ramp
• Motor protection: not included
• System protection:
not included
• Metering: not included
• Start/stop control: via inputs or via
optional controller
• Network communication: optional
• Bypass: Internally bypassed
MCD 202
• Soft start: Current limit
• Soft stop: Timed voltage ramp
• Motor protection:
Thermistor, Motor overload,
Phase imbalance
• System protection: Phase rotation,
Excess start time, Bypass overload
& Instantaneous overload
• Metering: optional extra
• Start/stop control: via inputs or via
optional controller
• Network communication: optional
• Bypass: Internally bypassed
MCD 201 and MCD 202
• Current: 7.5 kW ~ 110 kW @400 V
• Mains voltage: 200 ~ 575 VAC
• Supply frequency: 45 ~ 66 Hz
• Enclosure: 7.5 ~ 55 kW IP 20,
75 ~ 110 kW IP00
Danfoss Drives · DKDD.PB.551.A1.02 | 9
MCD 100
• Micro Soft Start Controller for
motors up to 11 kW
• Extremely robust SCR design with
heavy ratings as standard
• Unlimited number of starts per hour
• Contactor style design for easy
selection, installation and commissioning
MCD 100
• Current: 1.5 kW ~ 11 kW @400 V
• Mains voltage: 208 ~ 600 VAC
• Control voltage: 24 – 480 VAC/VDC
• Enclosure: 1.5 ~ 11 kW IP 20
10 | Danfoss Drives · DKDD.PB.551.A1.02
Current Ratings
These duty ratings dene the load requirements , not
the starter capabilities. Starter capability is specied
separately in User Manua ls, Product Guides and
WinStar t. Use these charts to select a soft starter for a
particular application.
Normal Heavy Severe
MCD 5-0 021B 21 (32) 17 (26) 15 (22)
MCD5 -0037B 37 (56) 31 (47) 26 (39)
MCD5-0043B 43 (65) 37 (56) 30 (45)
MCD5-0053B 53 (80) 46 (69) 37 (55)
MCD5-0 068B 68 (102) 55 (83) 47 (7 1)
MCD5-0084B 8 4 (126 ) 69 (10 4) 58 (87)
MCD5-0 089B 89 (134) 74 (112 ) 61 (92)
MCD5-0105B 105 (15 8) 95 (143) 7 8 (117 )
MCD 5-0131B 131 (197) 106 (159) 9 0 (136)
MCD5 -0141B 141 ( 212) 121 (181) 97 (14 6)
MCD5-0195B 195 (293) 160 ( 241) 134 (201)
MC D5- 0215B 215 (323) 178 (268) 149 (22 3)
MCD5-0245C 255 (383) 201 (302) 176 (264)
MCD5-0245B 245 (368) 19 4 (2 91) 169 (2 54)
MCD 5-0331B 331 (497 ) 266 (400) 229 (343)
MCD5-0360C 360 (540) 310 (465) 263 (395)
MCD5-0380C 380 (570) 359 (539) 299 (449)
MCD5- 0396B 396 (594) 318 (478) 27 3 (410)
MCD5-0428C 430 (645) 368 (552) 309 (4 63)
MCD5-0469B 469 (704) 383 (575) 326 (49 0)
MCD5-0525B 525 (787) 425 (637) 364 (546)
MCD5-0595C 620 (930) 540 ( 810) 434 (651)
MCD5 -0619 C 650 (975) 561 (8 42) 455 (683)
MCD5-0632B 632 (948) 512 (768) 438 (658)
MCD5-0790C 790 ( 1185 ) 714 (1072) 579 (869)
MCD5-0744B 744 (1116) 606 (910) 516 ( 774)
MCD5-0826B 826 (1239) 684 (1026) 571 (857)
MCD5-0927C 930 (1395) 829 (12 44) 6 61 (992 )
MCD5-09 61B 961 (14 41) 7 96 (119 4) 664 (997)
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Normal Heavy Severe
MC D5-12 00C 1200 (1800) 1200 (1800) 1071 (1607)
MCD5-1400C 1410 (2115) 1319 (197 9) 111 4 (16 71)
MCD5 -1600 C 1600 (2400) 1600 (2400) 13 53 (203 0)
All ratings are for bypassed operation.
Brackets denote ratings for inside delta connection.
Normal Heavy Severe
MCD 201-007 18 17
MCD 201-015 34 30
MCD 201-018 42 36
MCD 201-022 48 40
MCD 201-030 60 49
MCD 201-037 74 65
MCD 201-045 85 73
MCD 201-055 10 0 96
MCD 201-075 140 12 0
MCD 201-090 170 142
MCD 201-110 200 165
MCD 202- 007 18 17
MC D 202- 015 34 30
MCD 202-018 42 36
MCD 202- 022 48 40
MCD 202- 030 60 49
MCD 202-037 74 65
MCD 202- 045 85 73
MCD 202-055 10 0 96
MCD 202-075 140 12 0
MCD 202- 090 170 142
MCD 202- 110 200 165
Consult Danfoss
for suitability
Consult Danfoss
for suitability
12 | Danfoss Drives · DKDD.PB.551.A1.02
Soft Starter Sizing
• Th e soft start er’s current ratin g at the required st art duty must b e at least equal to th e
motor’s nameplate rating. If the motor’s nameplate rating is not available, approximate
information is available from the following table.
Motor Power Current rating at dierent voltages
kW HP 220-230 V 380- 400 V 4 40 V 500 V 660-690 V
7.5 10 27 15 .5 13.7 12 8.9
11 15 39 22 20.1 18.4 14
15 20 52 30 26.5 23 17. 3
18.5 25 64 37 32.8 28.5 21. 3
22 30 75 44 39 33 25.4
25 35 85 52 45.3 39.4 30.3
30 40 103 60 51.5 45 34.6
37 50 12 6 72 64 55 42
45 60 150 85 76 65 49
55 75 18 2 10 5 90 80 61
75 100 240 13 8 125 10 5 82
90 125 295 17 0 14 6 129 98
110 150 356 205 178 156 11 8
132 18 0 425 245 215 187 14 0
140 19 0 450 260 227 200 145
147 200 472 273 236 2 07 15 2
150 205 483 28 0 246 210 15 9
160 220 520 300 256 220 170
185 250 595 342 295 263 20 0
200 270 626 370 321 281 215
220 300 700 408 353 310 235
250 340 800 460 4 01 360 274
257 350 826 475 412 365 280
280 380 900 510 450 400 305
295 400 948 546 473 416 320
300 410 980 565 4 81 420 325
315 430 990 584 505 4 45 337
335 450 110 0 620 518 472 355
355 480 115 0 636 549 50 0 370
375 500 118 0 670 5 75 527 395
400 545 12 50 710 611 540 410
425 580 133 0 760 650 574 4 45
445 60 0 140 0 790 680 595 455
450 610 1410 800 690 608 460
475 645 149 0 850 730 645 485
500 680 15 70 900 780 680 515
560 76 0 1750 1000 860 760 570
600 800 1875 10 85 937 825 625
650 870 2031 1176 1015 894 67 7
700 940 2187 126 6 1093 962 729
750 1000 2343 1357 1172 1031 781
800 1070 2499 1447 12 50 110 0 833
850 114 0 2656 1537 1328 11 68 885
900 1250 2812 162 8 140 6 12 37 937
950 127 5 2968 1718 1484 13 06 989
1000 1340 3124 180 9 156 2 13 75 10 41
Note: Inform ation is based on a 4- pole motor
Danfoss Drives · DKDD.PB.551.A1.02 | 13
AAC: What is Adaptive Acceleration Control?
TIME
AAC is the next evolution in soft starter technology.
Using AAC, the soft starter learns your motor’s performance during
start and stop, then adjusts control to optimize performance.
The soft starter estimates the motor’s speed throughout each
AAC start and stop, and adjusts power to the motor to provide the
selected acceleration or deceleration profile.
AAC is largely unaffected by changes in load, and is particularly
suitable for pumping situations.
AAC offers three starting and stopping profiles: early, constant and
late acceleration/deceleration.
EARLY
CONSTANT
SPEED
LATE
AAC is only available on MCD 500 soft starters.
14 | Danfoss Drives · DKDD.PB.551.A1.02
LATE
CONSTANT
EARLY
AC53 Utilisation Codes: What are AC53 Utilisation Codes?
AC53 utilisation codes describe the current rating for soft starters
under specied operating conditions.
The utilisation code determines the maximum motor size the
soft starter can be used with, under the specied conditions. The
current rating may change under dierent operating conditions.
AC53a: Non-bypassed soft starters
The rating depends on the number of starts per hour, the length
and current level of the start, and the percentage of the operating
cycle that the soft starter will be running (passing current).
AC53b: Bypassed soft starters
The rating depends on the number of starts per hour, the length
and current level of the start, and the amount of time the soft
starter will be o (not passing current) between starts.
Danfoss soft starters provide a relay output, which can
be used to control the main contactor. Ensure that the
inrush VA rating of the contactor coil does not exceed
the rating of the sof t starter’s relay input.
Danfoss Drives · DKDD.PB.551.A1.02 | 15
Auto-Transformer Starters: How does soft start
compare to auto-transformer starting?
Soft starters are much more exible than auto-transformer starters
and provide a much smoother start, generally at a lower cost.
Auto-transformer starters cannot accommodate varying load
conditions (e.g. loaded or unloaded starts) and the start torque
cannot be freely adjusted to match motor and load characteristics.
Damaging torque and current transients still occur at the steps
between voltages, and auto-transformer starters are not capable
of providing soft stop. Auto-transformer starters are large and
expensive, especially if high start frequency is required.
Fault nding: What are the key questions?
To assist your service engineer, they require the following
information:
• Model and serial number of the soft starter
• Motor kW and FLC
• Main supply voltage and frequency
• Control voltage
• Application (e.g. pump, compressor)
• Time installed before failure
• Details of other soft starters on the supply bus. Are these failing?
• If the soft starter trips, details of the code and mode of operation
• The installation’s power and control schematic diagram
16 | Danfoss Drives · DKDD.PB.551.A1.02
Braking:
What are DC braking and soft braking?
DC braking and soft braking both reduce motor stopping time,
unlike soft stopping which increases the stop time on frictional
loads.
DC braking uses DC injection to reduce the motor’s stopping time.
The soft starter slows the motor to approximately 70% of its full
running speed, then applies brake torque to stop the motor in the
selected braking time.
DC braking support is built into MCD 500 soft starters, and no
additional equipment is required. MCD 500 DC braking controls all
three phases, which reduces stress on the motor compared with
two phase braking solutions.
Soft braking uses reversing contactors on the input side of the
starter to start the motor in the reverse direction, which applies
braking torque to the load.
Soft braking causes less motor heating and provides more
braking torque for a given current than DC braking, and is better
for extremely high inertia loads (e.g. band saw and circular saw
applications).
Danfoss Drives · DKDD.PB.551.A1.02 | 17
Bypass Contactors:
When should a bypass contactor be used?
Bypass contactors bridge out the SCRs when the motor is running
at full speed, eliminating heat dissipation during run. This allows
the soft starter to be installed in enclosures without the need for
forced-air cabinet ventilation.
If a soft starter is installed in a totally sealed enclosure (>IP 54) it
must be bypassed.
Bypass contactors should be AC1 rated for the motor FLC (the
bypass contactor does not carry start current).
Soft starters may be internally or externally bypassed:
MCD 200 sof t starters are i nternally bypas sed,
with built-in bypass relays.
MCD 500 sof t starters are i nternally bypas sed up to 500 kW.
Non-bypassed models include relay outputs to control an
external bypass contactor. Dedicated bypass terminals
mean moto r protection sti ll operates even when the sta rter
is bypassed.
18 | Danfoss Drives · DKDD.PB.551.A1.02
Cabling: How is cable selected for
a soft starter installation?
Cable selection criteria depends on the circuit and the location of
the soft starter within the circuit.
1. Supply cable rating > nominal fuse/MCCB rating > motor FLC x 1.2
2. Inside delta motor circuit cable rating > motor FLC x 0.7
Installation factors (including grouping, ambient
temperature, method of installation and single or
parallel cabling) may aect the cable’s current rating.
Always follow the manufacturer’s guidelines and derate
appropriately.
Danfoss Drives · DKDD.PB.551.A1.02 | 19
Cabling: What is the maximum allowable cable,
distance between a soft starter and the motor?
The maximum distance between the soft starter and motor
depends on the voltage drop and the cable capacitance.
Cable must be selected so that when the motor is running fully
loaded, the voltage drop at the motor terminals does not exceed
the limit specied in local electrical regulations.
For distances greater than 500 metres or when using parallel
cabling, cable capacitance may be a factor. If in doubt, please
contact Danfoss with details of the soft starter model, mains
voltage and frequency. If you want to use standard products, we
recommend using Line Reactors.
Calculation
The main point is to limit the di/dt so the SCR’s are not damage
with the inrush currents due to increase cable capacitance. The
output inductors must be installed as close to the soft starter as
possible.
The output inductors must be smaller than the inductance of the
motor.
Minimum rated current of coil, is stated from start current.
(Soft starter selection and application, normally 3 – 4,5 x FLC)
V
p
< L
di
(
dt
)
Vp Vp = V
di
dt
V Motor supply voltage
Ilr Locked rotor current
ω 2 × π × frequency
L
Coil Inductance
coil
20 | Danfoss Drives · DKDD.PB.551.A1.02
V
coil
(√3 I
) ω
LR
× √2
rms
100 A
.
1 μS
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