Soft Starter Selection Guide Soft starter selection requires information on the intended application, the features required, and the current rating of the associated motor. For applications with extreme or unusual conditions, consult the relevant Design Guide and/or your supplier. For example: •...
MCD Soft Starter Features and Specifi cations MCD 201 • 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 •...
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MCD3000 • Soft start: Current limit, Current ramp, Torque control, Torque boost • Soft stop: Timed voltage ramp, Pump control, DC brake, Soft brake • Motor protection: Thermistor, Motor overload, Phase imbalance • System protection: Phase rotation, Excess start time, Undercurrent, Instantaneous overload •...
Soft Starter Sizing • The soft starter’s current rating at the required start duty must be at least equal to the 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 diff...
(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 soft starter’s relay input.
Auto-Transformer Starters: How does soft start compare to auto-transformer starting? Soft starters are much more fl 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.
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.
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. Supply cable rating > nominal fuse/MCCB rating > motor FLC x 1.2 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 aff...
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For distances greater than 500 metres, cable capacitance may be a factor. Contact Danfoss with details of the soft starter model, mains voltage and frequency. ®...
If the soft starter will be used outside these conditions, the rating must be revised according to the manufacturer’s instructions. Ratings for Danfoss soft starters are published in the soft starter’s Design Guide. Alternatively, WinStart can be used to model requirements outside the published ratings.
Fault fi 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 •...
Flying Loads: Are soft starters suitable for use with a fl ying load? Soft starters can be used with fl ying loads (motors that are already rotating), without any special wiring or confi guration. As a general rule, the faster the motor is rotating in the forward direction, the shorter the start time will be.
Harmonics: Are harmonics an issue for soft starter applications? Harmonics are voltages and currents that create unwanted heating in motors, cables and other equipment. Harmonics may also disrupt operation of other electrical and electronic equipment. Soft starters generate very low levels of harmonics, only during starting or soft stopping.
Inside delta Connection: What is “inside delta” connection? With inside delta (six wire connection), the soft starter SCRs are in series with each motor winding so that the soft starter carries only phase current, not line current. The soft starter can thus control a motor with greater full load current than normal.
IP ratings IEC 60529 specifi es protection ratings for enclosures. The fi rst number describes the protection against solid objects, the second number describes the level of protection against entry of liquids. Example IP 20 is highlighted below. Liquids Solids No protection No protection.
NEMA ratings NEMA 250 is a product standard for enclosure design and performance. NEMA Protection against solid objects Approx. IP equivalent Indoor, protection from contact. IP 23 Indoor, limited protection from IP 30 dirt and water. Outdoor, some protection from rain, IP 64 sleet, windblown dust and ice.
Key Benefi ts: What are the key benefi ts of soft start? Soft start enhances motor start performance in many ways. • The gradual application of voltage or current avoids the voltage and current transients associated with electro-mechanical reduced voltage starters. •...
Line Contactors: When should a line contactor be used? Soft starters can be installed with or without a line contactor. A line contactor disconnects the SCRs from the supply when the motor is not in use. This isolates the soft starter, and protects the SCRs from damage due to severe overvoltage (e.g.
Minimum Start Current: What is the minimum start current required by a soft starter? Soft starters can limit start current to any specifi ed level, but the practical minimum depends on the motor and load. Reducing the start current reduces the torque produced by the motor, so the load will stall if the start current is too low.
Motor thermal capacity: What is it? Thermal capacity, also called “maximum locked rotor time” or “maximum DOL start time”, describes the maximum time a motor can run at locked rotor current from cold. This information is usually available from the motor datasheet. The MCD202 and MCD3000 overload protection can be set to match the motors thermal capability using the motors locked rotor time (cold).
Multiple motors: Can one soft starter be used to control multiple motors? A single soft starter can be used to control multiple motors, either in sequence or in parallel, provided the soft starter is correctly selected for the application. Motors in sequence For two or more motors in sequence, the soft starter must be capable of bearing the total start duty.
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Multiple Motors: Can one soft starter be used to control multiple motors? Motors in parallel For two motors or more in parallel, the soft starter FLC must be appropriate for the combined motor FLCs and each motor must have separate overload protection. A parallel starting installation requires careful attention to soft starter selection.
Power factor correction: Can power factor correction be used with soft starters? Power factor correction (PFC) capacitors can be used with soft starters, provided they are switched in using a dedicated contactor when the motor is running at full speed. PFC must always be installed on the input side of the soft starter;...
Primary Resistance Starters: How does soft start compare to primary resistance starting? Soft starters are more fl exible and reliable than primary resistance starters. Primary resistance starters cannot accommodate varying load conditions (e.g. loaded or unloaded starts) and the start torque cannot be fi...
Reversing: Can soft starters be used to reverse motor direction? On their own, soft starters cannot run motors in reverse direction at full speed. However, an arrangement of forward and reverse contactors can be used to provide the same eff ect. Some soft starters off...
Sealed enclosures: Can soft starters be installed in sealed enclosures? Soft starters can be installed in sealed enclosures, provided the ambient temperature within the enclosure will not exceed the soft starter’s rated temperature. All heat generated within the enclosure must be dissipated, either by ventilation or through the enclosure’s walls.
Short Circuit Protection: What is required for Type 1 short circuit protection of a soft starter? Type 1 protection requires that in the event of a short circuit on the output of a soft starter the fault must be cleared without risk of injury to personnel.
Short Circuit Protection: What is required for Type 2 short circuit protection of a soft starter? Type 2 protection requires that in the event of a short circuit on the output of a soft starter the fault must be cleared without risk of injury to personnel or damage to the soft starter.
320000 • Semiconductor fuses listed below are manufactured by Bussmann and should be ordered directly from Bussmann or their local supplier. Instruction for selection for alternate semi- conductor fuses is available from Danfoss. Bussmann Fuse Bussmann Fuse SCR I MCD3000...
Slip-Ring Motors: Are soft starters suitable for use with slip-ring motors? Soft starters are suitable for use with slip-ring motors provided that the motor can still deliver the torque required to accelerate the load. Soft starters are not suitable if the load requires extremely high start torque, or if the slip-ring motor is intended to provide speed control.
Soft Braking: What is soft braking? Soft braking is a technique used by the soft starter to reduce motor stopping time, unlike soft stopping which increases the stop time on frictional loads. Soft braking requires the use of reversing contactors. When the soft starter receives a stop command, it operates the reversing contactor connected on its input side to soft start the motor in the reverse direction.
Star/Delta Starters: How does soft start compare with star/delta starting? Soft starters are much more fl exible than star/delta starters and provide a smooth start with no risk of current or torque transients. Star/delta starters cannot accommodate varying load conditions (e.g. loaded or unloaded starts) and the start torque cannot be adjusted to match motor and load characteristics.
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Star/Delta Starters: Can soft starters be used to replace star/delta starters? If the soft starter supports inside delta connection, simply connect it in place of the star/delta starter. If the soft starter does not support inside delta connection, connect the delta connection to the output side of the soft starter.
Thermal Model Protection: How is a motor thermal model diff erent from other forms of overload protection? The motor thermal model used in MCD 202 and MCD3000 soft starters off ers precise motor protection normally only available from high- end motor protection relays. The thermal model constantly models motor temperature, based on information on the motor’s design characteristics and actual operation.
Two-Speed Motors: Are soft starters suitable for use with two-speed motors? Soft starters are suitable for use with Dahlander and dual winding motors, provided that separate motor protection is used for both low and high speed operation. Dual-winding motors have one shaft with two separate pole confi...
Types of Soft Starter: What are the diff erent types of soft starters? There are three diff erent types of soft starter which off er diff erent features and control the motor in diff erent ways. Torque controllers control only one phase during start. This reduces the torque shock at start but does not reduce start current.
• Monitor the soft starter thermal model overload temperature (MCD3000 and MCD202 only) Danfoss WinMaster is a PC Windows based software which allows control, monitoring and parameter management of soft starters on an RS485 network. The following information is a general guide to MCD3000 and MCD200 bus options.
RS485 starter side of the second Remote operator (terminals B1, B2, B3) • The Remote Operator requires an external 18-30 VAC/DC auxiliary supply. • For more information on the MCD Remote Operator, refer to the Users Manual (MG.17.Ex.02) located at www.danfoss.com/drives ® Soft Starter Pocket Guide...
The Remote Operator requires an external 18-30 VAC/DC auxiliary supply. • For more information on operating the MCD Remote Operator as a Modbus RTU gateway, refer to the MCD Modbus Module Installation Instructions (MG.17-Fx.02), Appendix A, located at www.danfoss.com/drives. ® Soft Starter Pocket Guide...
Up to 63 DeviceNet Gateways can be used as DeviceNet slaves on a single DeviceNet network. • The DeviceNet Gateway is powered via the network cable. • For more information on the MCD3000 DeviceNet Gateway, refer to the User Manual (MG.15.Ex.02) at www.danfoss.com/drives. ® Soft Starter Pocket Guide...
01, MCD Profi bus Gateway and Remote Operator compatibility. • For more information on the MCD3000 Profi bus Gateway, refer to the MCD Profi bus Gateway User Manual (V2.03) located at www.danfoss.com/drives. ® Soft Starter Pocket Guide...
The Serial Interface Module is powered by the MCD200. The Remote Operator requires an external 18-30 VAC/DC auxiliary supply. • For more information on the MCD Remote Operator, refer to the User Manual (MG.17.Ex.02)) located at www.danfoss.com/drives. ® Soft Starter Pocket Guide...
Up to 31 Modbus Modules can be used as Modbus slave devices on a single Modbus RTU network. • The Modbus Module is powered-up by the MCD200. • For more information about operating the MCD Modbus Module, refer to the Installation Instructions (MG.17.Fx.02), located at www.danfoss.com/drives. ® Soft Starter Pocket Guide...
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The Serial Interface Module is powered via the MCD200. The Remote Operator requires an external 18-30 VAC/DC auxiliary supply. • For more information about operating the MCD Remote Operator as a Modbus RTU gateway, refer to the Installation Instructions (MG.17.Fx.02), Appendix A, located at www.danfoss.com/drives. ® Soft Starter Pocket Guide...
The DeviceNet Module is powered via the network cable. • The MCD DeviceNet Module is ODVA tested and certifi ed. • For more information on the MCD DeviceNet Module, refer to the Installation Instructions (MG.17.Hx.02), located at www.danfoss.com/drives. ® Soft Starter Pocket Guide...
The Profi bus Module requires and external 24 VDC auxiliary supply. • The MCD Profi bus Module is Profi bus tested and certifi ed. • For more information on the MCD Profi bus Module, refer to the Installation Instructions (MG.17.Gx.02) at www.danfoss.com/drives. ® Soft Starter Pocket Guide...
Glossary AC53 Utilisation Code – The specifi cation of a soft starter’s current rating at intended operating conditions. Auger – a device which uses a screw-like mechanism to move material or liquid, similar to the process that drives shavings up a drill bit and out of a hole during drilling.
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Glossary Crusher, jaw – a crusher with one fi xed side and one moving “jaw”. The crusher is wider at the top than the bottom, and material is fed in at the top and moves down as it is broken into progressively smaller pieces. Crusher, roller –...
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Glossary Grinder – a machine which reduces the size of small particles through compression and attrition. For machines operating on larger items, see Crusher. Gyratory crusher – see Crusher, cone. Hydraulic power pack – A hydraulic pump which is used to supply pressurised hydraulic fl...
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Glossary Mixer – a machine which combines ingredients. Nameplate rating – See Full load current. NEMA – a description of the soft starter’s physical format, according to the National Electrical Manufacturers’ Association standard. Pelletiser – a machine which turns powders into pellets. Planer –...
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Glossary Rotary table – a large rotating table which is used to sort or move material. Sander – a machine which smooths raw material by abrading the surface. Saw – a machine which uses a serrated edge to cut materials. Saw, band –...
Abbreviations AC – Alternating Current DC – Direct Current DOL – Direct On Line FLC – Full Load Current FLT – Full Load Torque HRC – High Rupturing Capacity IP – International Protection kW – Kilowatt MCCB – Moulded Case Circuit Breaker PFC –...
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Christchurch: Tel. (03) 379 4365, Fax. (03) 379 4365 www.danfoss.com/pacifi c Email Australia: motioncontrols@danfoss.com.au Email New Zealand: drives@danfoss.co.nz After Hours Service Support: Australia Tel. 1800 063 330 • New Zealand (Nth) Tel. 09 259 2519 DKDD.PB.07.A2.02 VLT® is a trademark of Danfoss A/S Produced by SMC 2008.06...
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