Gingoog Electric Trading (G.E.T.) ™

May 2, 2009

Softstarter Comparison Table

Filed under: GET Softstarters — Ralf @ 3:26 AM

Danfoss Softstarter Comparison

Now this Danfoss Softstarters are really great stuff, come with state of the art technologies in compact solutions and include features and protective functions just as you need it.

The following quick overview in form of an easy table gives you a perfect idea about tha capabilities of each model and will surely assist you a good way in your further selections:

Type MCD-100 MCD-201 MCD-202 MCD 3000

Intro A true fit and forget Softstarter for DIN Rail mount.

It provides basic soft start and soft stop functions.

A physically compact Softstarter providing basic soft start and soft stop functionality. Physically similar to MCD-201 but providing enhanced soft start functionality and various motor protection features. The total motor starter solution providing numerous functionality to control starting and stopping plus protection of both motor and application.

Concept Soft start.

Soft stop.

0.1KW to 11KW.

208 to 600VAC mains supply.

24 to 480V AC/DC control voltage.

2 phase SCR control.

Soft start.

Soft stop.

7.5KW to 110KW.

200 to 575VAC mains supply

110 to 440VAC or

24V AC/DC control supply.

2 phase SCR control.

Current limit start.

Soft stop.

Motor protection.

200 to 575 VAC mains supply

110 to 440VAC or

24V AC/DC control supply.

2 phase SCR control.

Enhanced soft start and soft stop.

Motor and system protection.

7.5KW to 800KW.

200 to 690VAC mains supply

110 to 400VAC control supply.

3 phase SCR control.

Start Timed voltage ramp up.

Adjustable start torque.

Selectable kick start function.

Timed voltage ramp up.

Adjustable initial torque.

Current limit start.

Initial current ramp up.

Current limit start.

Initial current ramp up.

Torque control.

Torque boost.

Dual parameter function.

Stop Timed voltage ramp down. Timed voltage ramp down. Timed voltage ramp down. Linear voltage ramp down.

Three auto adjustable voltage ramps.

DC brake function.

Soft brake function.

Protection Motor overload.

Adjustable trip class.

Excess start time.

Reverse phase rotation.

Motor thermistor input.

Shorted SCR-no start

Supply fault-no start.

Instantaneous overload.

As MCD-202 plus

Under current.

Starter over temperature.

Restart delay.

Warning before trips.

Adjustable phase imbalance sensitivity.

Outputs One output relay.

Line contactor control.

Two output relays.

Line contactor control.

Run contactor or trip function.

Three output relays.

Line contactor control.

Run contactor or trip function.

DC brake contactor.

Control Universal two wire control.

Programmable via 3 rotary switches.

Two or three wire control.

Programmable via 3 rotary switches.

Reset push button.

Two or three wire control.

Programmable via 3 rotary switches.

Reset push button.

Local key pad.

Buttons for start, stop, reset and remote control.

Inputs for two or three wire control.

Options Modules for serial communication.

Remote operator kit.

PC software.

Modules for serial communication.

Remote operator kit.

PC software.

Modules for serial communication.

Remote operator kit.

PC software.

Others Extremely robust SCR.

Design for unlimited number of starts per hour.

LED indication.

IP20 enclosure.

Integral SCR bypass for minimum physical size and heat dissipation during nominal operation.

LED status indication

IP20 enclosure up to 55KW.

IP00 enclosure rated above.

Protection kit available.

Integral SCR bypass for minimum physical size and heat dissipation during nominal operation.

LED status indication

IP20 enclosure up to 55KW.

IP00 enclosure rated above.

Protection kit available.

Built in bars for easy connection of bypass contactor.

All motor protection functions retained in bypass mode.

Inside delta wiring kit (132 to 800KW).

Automatic reset function.

Password parameter protection.

Trip log function.

LED status indication.

IP21 enclosure up to 132KW.

IP20 enclosure rated above.

Please note that the MCD-500 is now released and the MCD-3000 is no longer manufactured

We could not understand it any better if you still have some open questions and we would love to attend to your inquiries, so please do not hesitate to contact us anytime.

Check for our GET Contact Details or simply use our GET Contact Form

Ralf Wabersich

Gingoog Electric Trading (G.E.T.)


April 3, 2009

Danfoss Softstarters

Filed under: GET Softstarters — Ralf @ 4:17 AM

Danfoss Softstarter intro and selection guide

Danfoss Softstarters protect gear, goods, equipment and environment

An AC electric motor switched directly on to the mains power supply will struggle to reach its nominal speed as quickly as possible.

This draws maximum current from the power supply and accelerates the application with its maximum torque. Depending on the exact application, this can cause different problems.

Applications like for example pumps, conveyers, centrifuges and band saws must be started slowly and sometimes stopped slowly to prevent mechanical shocks such as water hammer (also known as liquid hammer) and strains on bands, couplings and shafts.

A Softstarter is an electronic device that regulates the voltage to the motor and this provides a smooth transition from standstill to full speed operation of the particular application.

Danfoss VLT Softstarters all use the principle of phase angle control which means back to back coupled thyristors ramp up or down the motor voltage.

In some VLT Softstarters current transformers measure the actual motor current providing even more precise feedback for starting current control but also for numerous reliable motor and application protection functions.

Soft starting and soft stopping can be controlled in a number of ways, depending on the particular type of application.

Some applications require non linear voltage ramp up and the voltage ramp is therefore related to the actual current drawn. Conversely, a band saw usually requires a quick stop function provided by a DC brake.

Then again, a number of applications require a kick start torque for an instantaneous period of time followed by a soft ramp up acceleration. Danfoss VLT Softstarters do cover all of these applications and much more.

Softstarters are also an ideal upgrade to existing Star Delta, also known as Y-Delta and other conventional equipment such as Auto Transformers and the advantages are crystal clear.

Softstarters are indeed a far better alternative to Star Delta and Auto Transformer starters.

The Star Delta starter reduces start current at least somewhat but introduces still a damaging torque transient when switching from the Star to the Delta connection. Furthermore the Star Delta starting does not always allow selection of the best starting current level; it is in many cases not even a cheaper solution because Danfoss Softstarters don’t come with a heavy price tag. This sometimes means the load cannot accelerate to full speed in Star configuration, thereby making the Star Delta starter completely ineffective.

An addition a Star Delta starter does not impact at all the way the motor stops, thus leaving the voltage ramp down with no control.

The Auto Transformer on the other hand reduces start current as well but also allows some control over the level of start current. Auto Transformer starters do not however eliminate the risk of a jump in torque when shifting voltage, it lacks the often very necessary torque needed during ramp up and just like the Star Delta starter, the Auto Transformer leaves the stopping procedure completely without control.

We spoke already about quite a few general Softstarter benefits but here we would like to go just with a quick summary into some more application specific advantages in order to paint an even much clearer picture on what exactly we gain when using a Danfoss Softstarter.

Benefits on pumps:

Reduced hydraulic shocks in pipelines during start and stop

Minimized mechanical stress on motor shaft, bearings and many other mechanical components

Reduced starting current

Undercurrent protection preventing damages from a blocked pipe or low water situations (MCD 3000)

Phase rotation protection prevents damages from reverse pump rotation (MCD 202 and MCD 3000)

Instantaneous overload protection prevents damages from debris drawn into the pump (MCD 202 and MCD 3000)


Controlled start without mechanical shocks causing damages to both application and even to the products

Minimized belt stretch and reduced counter balance stress

Controlled stop without mechanical shocks

Optimum soft start even with varying starting loads like for example conveyors starting loaded or unloaded (MCD 202 and MCD 3000)

Extended mechanical life time


Reduced mechanical shocks extend the life of the compressor, couplings and motor

Limited start current enables large compressors to be started even when maximum power capacity is limited

Phase rotation protection prevents operation in reverse direction (MCD 202 and MCD 3000)

Instantaneous overload protection prevents possible damages from liquid ammonia or other refrigerants entering the compressor screw (MCD 202 and MCD 3000)


Smooth application of torque preventing mechanical stress

Reduced starting times over Star Delta starting


Smooth application of torque preventing mechanical stress

Reduced starting times over Star Delta starting

Reduced stopping times due to DC brake and soft braking (MCD 3000)

Band saws

Reduced time for saw band replacements since the soft braking function stops the motor quickly (MCD 3000)

Extended saw band life thanks to eliminated torque shocks during start

Easier saw band alignment, slow acceleration allows saw bands to be tracked without jogging

Maximum overload capability available to ride through of operating overloads (MCD-3000)

The motor thermal model (MCD 202 and MCD 3000) accounts for the actual overload capability of the connected motors and will trip only if absolutely necessary

OK, now that we know already that there is no way around, now that we know that we really need a Softstarter in our circuits, now which model is tailored for our needs?

The selection is quite easy. Danfoss offers three different models. To keep the things simple we are going to introduce them here with just a few comprehensive pointers but just as always we do include of course our downloadable links here for your further and more enhanced studies.

Danfoss Softstarter MCD 100

The smallest Danfoss Softstarter is our MCD 100 which is a cost effective and extremely compact Softstarter for AC motors up to 11.0KW due to a unique and robust semiconductor design. It is a true fit and forget product and selection can be simply made on the basis of the motor power, exactly as with traditional contactors. It comes with heavy ratings as standard, allows a unlimited number of starts per hour and is truly easy to install and to commission.

Please download here the MCD-100 Design Guide plus this very helpful Softstarter Pocket Book.

Danfoss Softstarter MCD 200

Due to extensive use of the latest technologies, such as for example the new semiconductor control algorithms and bypass design this new Softstarters are very compact and heat dissipation is very low. There is no need for extra ventilation or additional bypass contactors, this features are actually already built in which does not only lower the total cost but also simplifies the installation and keeps panel space at a minimum. It ranges up to 110KW, comes with advanced accessory modules, offers voltage ramps, current limit start and integrated motor protection when opting for the MCD-202 version.

Please download here the MCD-200 Brochure and also the MCD-200 Design Guide.

Danfoss Softstarter MCD 3000

This is a total motor starting solution. Current transformers measure the motor current and provide feedback for controlled motor voltage ramp up but also for numerous motor protection features. A numeric display and logic keypad buttons make programming easy and an operational status such as for example current and other data are showed via the display. Digitally fully featured and ranging up to 800KW, a very advanced tool, the ultimate solution, ready to perform.

Please download here the MCD-3000 Brochure and check out also all available parameters in the MCD-3000 Instruction Manual.

Another overview is also available at the download section of our Danfoss Softstarter Page.

Now NEW: The state of the art Danfoss Softstarter MCD-500

Do not forget to contact your friendly GET agent to get more answers to your pending questions. Simply use the GET Contact Form.

Ralf Wabersich

Gingoog Electric Trading (G.E.T.)

April 2, 2009

Why Softstarters?

Filed under: GET Softstarters — Ralf @ 10:45 AM

Softstarters and their benefits

The word Softstarter originated of course from the idea to start something in a soft and smooth way.

Soft start is an electronics term describing any circuit which reduces excess current during initial power-up.

Electric motors for example will consume a large initial current, also known as the starting current or inrush current when first turned on. That can cause voltage fluctuations and affect the performance of other circuits connected to a common power supply.

High initial current can cause damage to other components such as semiconductors or other electronic and electric devices if they are not rated for the initial high current of loads such as but not limited to filament lamps, electric motors itself or capacitors.

The current drawn by an electric motor during a start can be 2 to 10 times in extreme situations but usually averages in the most common applications to 5 or 6 times the normal operating current, and this can quickly exceed the supply’s ratings if not controlled.

The solution we want to highlight here is a Softstarter.

A Softstarter is a device used to ramp up or down AC electric motors by temporarily reducing the load in the power train of the motor during startup or stopdown. This reduces the mechanical stress on the motor and shaft, as well as the electro dynamic stresses on the attached power cables and electrical distribution network, extending the lifespan of the system quite significantly.

Let us go now a little bit deeper into all the benefits that come along with Softstarters:

As pointed out already, Softstarters save costs not only on the electrical side but also or even much more so on a variety of mechanical aspects.

Statistics show that about 90% of the motors in industrial use have no form of control, other than simple electromechanical switching. This results in huge industry costs in maintenance and equipment replacement. Fitting Softstarters could reduce these costs dramatically but where should the initiative come from, the electrical engineer or the mechanical engineer? If this seems a strange question, consider for a moment where the main benefits of fitting soft starters accrue.

The electrical engineer benefits in two ways.

By avoiding the dips in mains voltages that occur due to current peaks inherent in “Across the Line Starting”.

By avoiding the considerable stresses on the motor windings, and the iron cores of the stator and rotor, which result in reduced motor life, especially important in larger horsepower motors.

Although these benefits are considerable, the benefits to the mechanical engineer are greater still. This is because the sudden impact at startup of uncontrolled starting, followed by the rapid acceleration to full speed, causes problems across a wider range of equipment types.

Sudden torque stresses cause excessive wear on belts, pulleys, gears, chains, couplings and bearings, and also cavitations in pumps, which reduces their efficiency and life. Similarly, shock waves can be generated and transmitted along hydraulic pipe work, weakening joints in pumping systems. In conveyor systems, too, loads may be displaced or damaged on startup, and products may become contaminated.

Clearly then, mechanical engineers have more reasons to press for the fitting of Softstarters in fixed speed motor applications. Especially so, as the cost savings resulting from reduced downtime and from not having to replace bearings, gears, pulleys and bearings so frequently, will ensure quick payback on any soft starter unit.

A further argument for the mechanical engineer in fitting soft starts is that equipment previously left running, due to concerns about it restarting and also concerns regarding belts breaking, shafts shearing and bearings failing can now be switched off, enabling real savings in energy to be achieved.

Similar savings can also result if there is a breakdown situation. Taking the example of a blockage in a mill, historically all other motors have been left running when this situation occurred, even though the time required to remove the blockage was considerable. Today, this cost can be avoided simply by employing soft starters on the motors, enabling them to be switched off with no negative consequences for restarting.

This example deals with a breakdown situation. Prevention, however, is always better than cure. Modern manufacturing processes employ large numbers of pumps to convey everything from water to hazardous fluids. In many applications these pumps are driven by motors, which have no form of control during their starting and stopping.

As a result, pressure surges and water hammer occur, which can damage pipe work and equipment. Soft starters provide a solution to this problem with a feature known as “ramp down”. Intended for use where heavy dynamic loads are encountered, ramp down is particularly useful in pumping applications where it ensures that pump motors stop progressively, thus minimizing hammer or so called fluid shocks.

Another soft starter feature especially relevant to mechanical engineers is the “Electronic Shear Pin”. The Electronic Shear Pin enables the soft starter to cater for situations where loads are likely to jam suddenly, such as in wood sawing, rock crushing, wood chipping, etc. The traditional method of achieving this protection was via a mechanical shear pin that consisted of a pin of a deliberately weak material inserted into two concentric shafts at a convenient point in the drive train to the load. If the load became jammed, the sudden rise in torque would cause the pin to shear so that the two shafts could then rotate independently, thereby disconnecting the motor from its load. Before the load could be restarted, the old pin would need to be removed and a new one inserted an obviously inconvenient and time consuming process. The Electronic Shear Pin facility eliminates the need for a mechanical shear pin entirely because the speed and extent of a sudden and rapid rise in motor torque is immediately detected by the Softstarter which will then decide on a course of actions ranging from instantaneous shutdown to monitoring for recurrences if the blockage is released rapidly.

Soft starters provide an electronic solution to mechanical problems at relatively low cost. They can extend the life of belts, chains, gearboxes, shafts, bearings and machine mountings.

In addition, Softstarters can achieve real savings in energy for users by providing the facility to switch motors off, without fears for their restarting. Added to these factors, traditional fit and forget reliability ensures security of operation even in the most critical of tasks.

Here we would like to refer to our Booster pump presentation which illustrates how to maintain a constant pressure in a booster pump application plus the Cascading pump presentation which explains how Softstarters can become a component in real automation projects and help a lot to save plenty of energy. The same principle could be used by the way also for compressors in an airconditioning or refrigeration circuit and similar applications wherein several motors are working together to achieve a certain performance.

New generation softstart technologies offer meanwhile even much more than just start and stop control of electric motors. They do perform not only complete motor control but also motor protection and interface systems.

A summary of the most significant benefits:

Elimination of water or fluid hammer

Softstart gradually increases pump speed and fluid velocity. This eliminates completely damaging pressure surges and reduces maintenance costs.

Increased start capability

Softstarters allow electric motors to be started and stopped very frequently to maintain optimum system performance without any fear of mechanical damages to the motor or its attached machine.

Reduced maintenance costs

Maintenance costs for systems using Softstart control are very much reduced because the damaging mechanical stresses of motor starting and stopping are equally reduced.

Prevent interference to electrical and electronic equipment

A Softstarter enables electric motors to be started and stopped in close proximity to other equipment without causing interferences such as for example disrupting computers, programmable logic controllers (PLC’s), etc, extinguishing high pressure discharge lighting or electrical disruption to domestic consumers.

Install equipment in areas with weak electrical supplies without the cost of upgrading

A Softstarter can be used to limit the starting current to the maximum possible level. This means large motors can often be installed in areas with weak or limited electrical supplies and without the expenses of installing a new, a better, an upgraded, a higher rated electrical supply system.

Gradually decelerate speed, hence fluid movement

Damage caused by water or fluid hammer can be entirely eliminated through the use of a soft stop which slows down for example a pump operation over an extended and adjustable, meaning customizable period of time so that fluid velocity is likewise gradually reduced, thus preventing potentially and literally damaging pressure surges in the system.

Phase sequence protection

Reverse pump rotation or any dangerous reverse motor rotation can be prevented by enabling the Softstarter’s phase sequence protection.

Electronic shearpin protection

Storm water, sewage or other pumps moving fluids may carry very damaging solid debris but they can be protected using the Softstarter’s Electronic Shear Pin feature. As explained already above there are many other application examples which may benefit from this feature. Basically it finds its use  wherever loads are likely to jam unexpectedly like for example in wood sawing, rock crushing, wood chipping, etc. Electronic Shear Pin operates immediately once it detects that a machine is about to stall and thereby prevents mechanical damages.

Undercurrent protection

Protects motors against damages caused by running dry through the use of undercurrent protection. The motor’s running current is monitored to determine that it is under load indeed. This is also known as the “Loss Of Prime” feature, so in the case of a pump application it would sense when the pump starts to run dry, meaning it doesn’t carry water anymore but is filled with air. The current falls and the starter stops the pump to prevent otherwise unavoidable damage.

Programmable motor thermal model

Closed loop Softstart units provide motor overcurrent protection as an integral function. The level of this motor protection varies from basic to extremely advanced programmable motor thermal modeling.

Phase imbalance

Motor damages caused by unbalanced phases can be prevented by Softstarters with the phase imbalance protection. This can be very important when equipment is installed in remote areas with poor supplies.

Thermistor protection

Motor thermistors may be interfaced directly with a Softstarter to provide additional thermal motor protection.

System interface

Softstarters can be easily interfaced with all manners of control options, including telemetry systems for remote controls.

Serial communication

For integration with advanced control systems Softstarters nowadays are provided with serial communication capabilities.

We will go more into the details of Danfoss Softstarters in particular when we write the next article but at least we hope that we were able to let you gain already a general overview about Softstarters and how powerful, yet still simple they actually really are.

Allow me to introduce here again this comprehensive presentation:

Ralf Wabersich

Gingoog Electric Trading (G.E.T.)

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