Product Specific:
keywords
• How do I select a CSX Series soft starter for duty cycles different from those listed in the standard ratings table?
Use WinStart to select soft starters for different duty cycles. CSX, CSXi, selection, duty cycle
• What are the CSX Series operational ratings before maintenance may be required?
The operational ratings are:
Models 007~055: 1,000,000 operations
Models 075~110: 100,000 operations CSX, CSXi, maintenance, MTBF, operational rating
• What is the current consumption of the CSX Series control supply?
The steady state consumption of the control supply is 100 mA maximum, for both C1 and C2 models.
However, the short time inrush current at control supply switch-on can be as high as 10 A for C1 models, and 2 A for C2 models. CSX, CSXi, current consumption, control supply
• What is the impedance of the control inputs? Are any special precautions necessary during installation?
The impedance on terminals 01, 02 is approximately 150 kΩ @ 300 VAC and 5.6 kΩ @ 24 VAC/VDC. CSX, CSXi, installation, impedance, control inputs
Why is it necessary to apply control voltage before mains voltage at first power-up?
The soft starter may arrive at site with the internal bypass relays closed. When control voltage is applied, the bypass relays are commanded to open. If mains voltage is applied without control voltage, this step is missed and the motor may start direct on-line without warning. CSX, CSXi, installation, control voltage, bypass relays
• Why is the starting current higher on the middle phase than on the other two phases?
During a soft start, the CSX controls the two outside phases (L1-T1 and L3-T3), but the middle phase (L2-T2) is uncontrolled. The current on the uncontrolled phase is higher than on the other two phases (usually by 20%-25%), but is still lower than for an uncontrolled start. CSX, CSXi, current control
• Will the motor start DOL if the start ramp of a CSX open loop soft starter is set to full voltage?
No, the CSX will still provide a limited soft start. The voltage is ramped up from 0 to 100% in approximately 0.25 seconds. CSX, DOL, TVR, voltage ramp, soft start
What is the minimum size of motor that can be controlled using a CSX open loop soft starter?
There is no minimum motor size when using a CSX open loop soft starter. CSX, motor size
What is the minimum size of motor that can be controlled using a CSXi closed loop soft starter?
Motors connected to a CSXi soft starter must have a full load current rating ≥ 50% of the CSXi nameplate rating. All the motor protections are based on this setting.
It is possible to operate a CSXi with a small kW motor, for testing purposes. In this case, the motor will effectively start direct on-line, and the CSXi will not protect the motor. The starter will not trip, because there is no undercurrent protection on the CSXi. CSXi, motor size
• What type of motor protection does the CSXi have?
The CSXi has built-in motor overload protection of the electronic thermal model type. The soft starter continuously monitors motor current and calculates the motor temperature from this information.
The rate of rise of the calculated motor temperature is determined by the Motor Trip Class setting. The lower this setting, the faster the rate of rise of calculated motor temperature. A Motor Overload trip will occur when the calculated temperature reaches 105%. This protection is similar to a motor trip class setting on a standard thermal overload relay.
An external motor protection device is not required when using a CSXi soft starter. CSXi is certified to conform to the IEC 60947-4-2 standard for electronic soft starters. The reliability of the motor protection feature is part of this standard. CSXi, motor protection, IEC 60947
• Is the CSXi suitable for flying start application?
Yes. There is a built-in two second delay between the end of one stop and the beginning of the next start. This allows the motor flux to decay, preventing the soft starter tripping on Power Circuit fault due to detection of motor back EMF when the start signal is applied. The major effect of a flying start is on the actual time the CSXi current limits. The ramp-up time will be reduced and depends on the motor's speed when the start signal is re-applied. CSXi, flying start, start delay, restart
• When should I use a main contactor?
Local regulations may require you to install a main contactor or circuit breaker, to completely disconnect the soft starter from mains voltage in the event of a trip. circuit configuration, system design, line contactor, main contactor
• When would I use semiconductor fuses?
Either when specified for an installation, or when Type 2 coordination is required.
The CSX Series is internally bypassed, so the SCRs are in use only during starting and soft stopping. circuit configuration, system design, fuse, semiconductor fuse, CSX, CSXi
• How do I size the fuses of the motor branch circuit when using a CSX Series soft starter?
For current limit settings ≤ 350% and start times ≤ 15 seconds, the nominal rating of standard line supply fuses should be 1.75 x Motor FLC. If motor rated fuses are being used, their nominal rating should be 1.5 x Motor FLC.
For current limit settings > 350% and start times > 15 seconds, the nominal rating of standard line supply fuses should be 2 x Motor FLC. If motor rated fuses are being used, their nominal rating should be 1.75 x Motor FLC. circuit configuration, system design, CSX, CSXi, fuse
What are IP ratings?
IEC 60529 specifies protection ratings for enclosures. These ratings describe the level of protection against dust and liquids entering the enclosure.
IP ratings consist of two numbers. The first number describes the protection against solid objects and the second number descibes the level of protection agains entry of liquids.
IP Solids Liquids
0 No protection No protection
1 Protected against solid objects greater than 50 mm (eg accidental touching by hand). Protected against vertically falling drops of water (eg condensation)
2 Protected against solid objects greater than 12 mm (eg fingers). Protected against direct sprays of water up to 15° from vertical.
3 Protected against solid objects greater than 2.5 mm (eg tools or wires). Protected against sprays of water up to 60° from vertical.
4 Protected against solid objects greater than 1 mm (eg tools and small wires). Limited protection against water sprayed from all directions (limited ingress permitted).
5 Limited protection against dust (some ingress but no harmful deposit). Limited protection against low pressure jets of water from all directions (limited ingress permitted).
6 Complete protection against dust. Protected against strong jets of water (limited ingress permitted).
7 Protected against the effects of immersion in water between 15 cm and 100 cm.
8 Protected against extended immersion in water under pressure.
• IP ratings, NEMA, physical protection
What are NEMA ratings?
• NEMA 250 is a product standard that addresses many aspects of enclosure design and performance.
Protection against solid objects Approx IP equivalent
1 Indoor, protection from contact. IP23
2 Indoor, limited protection from dirt and water. IP30
3 Outdoor, some protection from rain, sleet, windblown dust and ice. IP64
3R Outdoor, some protection from rain, sleet and ice. IP32
4 Indoor or outdoor, some protection from windblown dust, rain, splashing water, hose-directed water and ice. IP66
4X Indoor or outdoor, some protection from corrosion, windblown dust, rain, splashing water, hose-directed water and ice. IP66
6 Indoor or outdoor, some protection from ice, hose-directed water, entry of water when submerged at limited depth. IP67
12 Indoor, protection from dust, falling dirt and dripping non-corrosive liquids. IP55
13 Indoor, protection from dust, spraying water, oil and non-corrosive liquids. IP65
IP ratings, NEMA, physical protection
What are AC53 Utilisation Codes and what do they tell me about the soft starter’s current rating?
The AC53a Utilisation Code defines the current rating and standard operating conditions for a non-bypassed soft starter.
The soft starter’s current rating determines the maximum motor size it can be used with. The soft starter's 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).
The soft starter’s current rating is only valid when used within the conditions specified in the AC53a code - the soft starter may have a higher or lower current rating in different operating conditions.


The AC53b Utilisation Code defines the current rating and standard operating conditions for a bypassed soft starter (internally bypassed, or installed with an external bypass contactor).
The soft starter’s current rating determines the maximum motor size it can be used with. The soft starter's 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 off (not passing current) between starts.
The soft starter’s current rating is only valid when used within the conditions specified in the AC53b code - the soft starter may have a higher or lower current rating in different operating conditions.
AC53, AC53a, AC53b, current rating
Main contactors: when and how should they be used?
Soft starters can be installed with or without a main contactor.
A main contactor:
- may be required to meet local electrical regulations.
- provides physical isolation when the starter is not in use and in the event of a soft starter trip.
Even in the off state SCRs do not offer a high degree of isolation due to leakage through the SCR and protection networks.
- protects the soft starter SCRs from severe overvoltage situations (eg lightning strikes).
SCRs are most susceptible to overvoltage damage when in the off state. A main contactor disconnects the SCRs from the supply when the motor is not running, preventing possible damage.
Main contactors should be AC3 rated for the motor FLC.
AuCom 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 output.
circuit configuration, system design, line contactor, main contactor
Bypass contactors: when and how should they be used?
Bypass contactors bridge out a soft starter’s SCRs when the motor is running at full speed. This eliminates heat dissipation from the SCRs during run state.
Some soft starters include built-in bypass contactors, others require an external bypass contactor.

Bypass contactors:
- allow soft starters to be installed in sealed enclosures
- eliminate the cost of forced-air cabinet ventilation
- save energy by eliminating SCR losses during run
Bypass contactors should be AC1 rated for the motor FLC. The AC1 rating is adequate because the bypass contactor does not carry start current or switch fault current.
AuCom's CSX & CSXi soft starters have built-in bypass relays.
• IMS2 soft starters provide relay outputs to control an externally connected bypass contactor. Dedicated bypass terminals mean motor protection still operates even when the soft starter is bypassed. circuit configuration, system design, bypass contactor
Inside delta connection: what is it and why would I use it?
Inside delta connection (also called six-wire connection) places the soft starter SCRs in series with each motor winding. This means that the soft starter carries only phase current, not line current. This allows the soft starter to control a motor of larger than normal full load current.

When using an inside delta connection, a main contactor or shunt trip MCCB must also be used to disconnect the motor and soft starter from the supply in the event of a trip.
Inside delta connection:
- simplifies replacement of star/delta starters because the existing wiring can be used.
- may reduce installation cost. Soft starter cost will be reduced but there are additional cabling and main contactor costs. The cost equation must be considered on an individual basis.
Only motors that allow each end of all three motor windings to be connected separately can be controlled using the inside delta connection method.
Not all soft starters can be connected in inside delta.
AuCom's CSX & CSXi soft starters cannot be installed using inside delta connection.
• AuCom's IMS2 soft starters can be installed using an inside delta connection. circuit configuration, system design, motor connection, inside delta, wye delta, six-wire
Power factor correction: can it be used with soft starters?
Individual power factor correction capacitors can be used with soft starters, provided that they are installed on the input side of the soft starter and switched in using a dedicated contactor when the motor is running at full speed. The contactor should be AC6 rated for the motor full load current.
Connecting power factor correction capacitors to the output of a soft starter will cause equipment failure due to severe overvoltage. This overvoltage is created by resonance between the inductance of the motor and the power factor capacitance.

PFC capacitors can be sized using the following formula:
kVA (Cap) = √3 x Vline x 0.8 x motor no load current
• circuit configuration, system design, power factor correction
How do I achieve Type 1 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. There is no requirement that the soft starter must remain operational after the fault.
Type 1 protection is provided by HRC fuses or a MCCB that form part of the motor branch circuit.

• As a minimum, the protection method must be able to sustain the required motor start current. Typical selection criteria are listed below.
Rating (% Motor FLC)
Start Current
Starter Type Protection < 350% FLC
15 seconds > 350% FLC
15 seconds
CSX(i) Fuse (non-time delayed) 175% 200%
Fuse (time delayed) 150% 175%
MCCB* 150% - 200%
150%
125%
150% - 200%
IMS2 Fuse (non-time delayed)
Fuse (time delayed)
MCCB*
* Consult the manufacturer’s specification
Maximum fuse ratings for Type 1 motor protection are specified in UL and IEC standards
Rating (% Motor FLC)
Fuse (non-time delayed) 300%
Fuse (time delayed) 175%
circuit configuration, system design, protection, Type 1 coordination, fuses, circuit breaker, MCCB
How do I achieve Type 2 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.
Type 2 protection is achieved by using semiconductor fuses. These fuses must be able to carry motor start current and have a total clearing I2t < the I2t of the soft starter SCRs.
Semiconductor fuses for Type 2 circuit protection are additional to HRC fuses or MCCBs that form part of the motor branch circuit protection.

• Refer to the soft starter's Product Guide for semiconductor fuse recommendations. circuit configuration, system design, protection, Type 2 coordination, fuses, circuit breaker, MCCB
Cable selection: how do I select cable when installing a soft starter?
Cable selection criteria vary according to the nature of 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. 6 Wire (Inside Delta) Motor Circuit Cable Rating
> motor FLC x 0.7
Note: Cable current ratings may need to be derated to account for installation factors (grouping, ambient temperature, single or parallel cabling etc). Always follow the manufacturer's instructions. circuit configuration, system design, cable size
What is the maximum allowable length of cable run between a soft starter and the motor?
The maximum distance between the starter and motor is determined by the voltage drop and the cable capacitance.
Voltage drop at the motor terminals must not exceed the limit specified in local electrical regulations when the motor is running fully loaded. Cabling should be sized accordingly.
• Cable capacitance can be a factor for cable runs that are longer than 500 metres. Consult the soft starter manufacturer for advice - you will need to provide details about mains voltage, mains frequency and the soft starter model. circuit configuration, system design, protection, cable length, distance
Can I replace a star/delta starter with a soft starter?
Yes.
If the soft starter is capable of inside delta connection, simply connect it in place of the star/delta starter.

If the soft starter is not capable of inside delta connection, connect the delta connection to the output side of the soft starter.

IMS2 soft starters can be installed using an inside delta connection.
• CSX & CSXi soft starters cannot be installed in inside delta. circuit configuration, system design, motor connection, inside delta, wye delta, six-wire, star/delta
Slip-ring motors: can they be started with a soft starter?
Yes, provided that the torque available from the motor under the new configuration is sufficient to accelerate the load. This may be difficult to determine and a trial may be required.
Soft starting is not suitable for applications where:
- the slip-ring motor was installed to deliver speed control.
- the load requires extreme start torque.
To develop starting torque, some resistance must remain in the rotor circuit during motor starting. This resistance must be bridged out using a contactor (AC2 rated for rotor current) once the motor is running close to full speed.

Rotor resistance (R) can be sized using the following formula:
R (per phase) = 0.2 x

Where VR = open circuit rotor voltage
IR = full load rotor current
Power (per phase) = 20% x motor kW
3 circuit configuration, system design, motor connection, slip-ring motor
Two-speed motors: how do they work and can I use a soft starter to control them?
Soft starters can be applied to the two most common types of two-speed motor. In both cases, separate motor protection must be provided for low and high speed operation.
Dahlander motors are special purpose motors often applied to two-speed compressor or fan applications. The motor windings are externally configured using contactors for high speed (dual star) and low speed (delta) operation.

Dual-winding motors have two separate pole configurations (e.g. 4 pole / 8 pole) on a common shaft. Each pole configuration (speed) is selected using an external AC3 rated contactor.

AuCom's CSX soft starters are designed for use with external motor protection devices and are ideal for two-speed motor applications. CSXi soft starters (with built in motor protection) are less suitable.
IMS2 soft starters are ideal for two-speed motor applications. Dual motor settings allowing separate start profile settings for each speed. circuit configuration, system design, motor connection, two-speed motor, dual speed motor, dahlander motor
Can I use one soft starter to separately control mutiple motors for sequential starting?
Yes, one soft starter can control two motors in sequence. However, the control and wiring is complex and expensive and any saving in soft starter cost is often outweighed by additional component and labour costs.
In order to use a soft starter in a sequential starting situation,
1. Each motor must have a separate:
- main contactor
- bypass contactor
- overload protection
2. The soft starter must be suitably rated for the total start duty.
circuit configuration, system design, motor connection, multiple motors
Can I use one soft starter to control multiple motors for parallel starting?
Yes. The circuit configuration and soft starter selection depends on the application.
1. Each motor must have its own overload protection.

2. If the motors are the same size and are mechanically coupled, a constant current soft starter can be used.
3. If the motors are different sizes and/or the loads are not mechanically interlocked, a soft starter with a timed voltage ramp (TVR) start profile should be used.
4. The combined motor FLCs must not exceed the soft starter FLC.
IMS2 starters provide constant current starting and can be used to parallel start motors which are the same size and mechanically coupled.
CSX starters provide TVR starting and are designed for use with external motor protection devices. CSX starters are ideal for starting motors in situation (3) circuit configuration, system design, motor connection, multiple motors
Soft braking: what is it and when would I use it?
Soft braking is one of two techniques used by soft starters to shorten motor stopping time. The other technique is DC braking.
Soft braking uses reversing contactors on the input of the soft starter. When the soft starter receives a stop command, it operates the reversing contactors and the motor is effectively soft started in the reverse direction. This applies a braking torque to the load.

Compared to DC braking, soft braking:
- causes less motor heating
- provides more braking torque for a given current
Soft braking is better for extremely high inertia loads. brake, braking, soft stop, soft braking, DC brake
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, forward and reverse operation can be achieved by using a forward and reverse contactor arrangement.

Some soft starters also provide a part speed function that runs the motor at slow speed in either forward or reverse, without a reversing contactor. However, reverse operation is limited to short periods at a fixed slow speed. slow speed, jog, reversing
How do I select the right soft starter for extreme conditions?
The published ratings for soft starters assume a particular operating environment. If the soft starter needs to operate outside the assumed conditions, the rating must be revised according to the manufacturer's instructions.
Typical factors include:
- Start current
- Start time
- Start frequency (number of starts per hour)
- Duty cycle
- Ambient temperature
- Altitude
For AuCom soft starters:
- Refer to the Product Guide or User Manual for ratings.
- Use WinSTART to model performance requirements not covered by the published rating tables.
Ratings for AuCom soft starters are published in the soft starter's Product Guide. You can also use WinSTART to model requirements outside the published ratings. selection, duty ratings, extreme conditions, operating environment
What do I need to consider when I install a soft starter in a sealed enclosure?
Soft starters can be installed in sealed enclosures provided the ambient temperature within the enclosure will not exceed the soft starter's rated temperature.
Heat generated within the enclosure must be dissipated, either through the enclosure's walls or by ventilation. When calculating the heat generated in the enclosure, all heat sources must be considered (eg soft starter, fuses, cabling, switchgear etc). The enclosure should be protected form direct sunlight to prevent external heating.
To minimise heating, most soft starters are installed in bypassed configuration.
AuCom’s WinSTART program includes a function to help design enclosure ventilation. ventilation, installation, duty ratings, temperature
Harmonics: are they an issue for soft start applications?
Harmonics are voltages and currents that create unwanted heating in motors, cables and other equipment. Harmonics can also disrupt operation of electronic equipment.
Harmonic generation by soft starters is insignificant and only occurs during starting or soft stopping. IEC 60947-4-2 (8.3.2.1.1) states “harmonic emissions are of short duration during starting, and there are no significant emissions in the FULL-ON state.
No special actions or filtering are required.
All AuCom soft starters comply with the EMC directive on radiofrequency emissions and immunity. harmonics, EMC, EMI, interference, FCC
What is the minimum start current I can expect if I use a soft starter?
Soft starters can limit start current to any desired level. However, the minimum level of start current for a successful start depends on the motor and load.
To start successfully, the motor must produce more acceleration torque than the load requires, throughout the start.
Reducing the start current also reduces the torque produced by the motor. The start current can only be lowered to the point where the torque output remains just greater than the load torque requirement.
The likely start current can be estimated from experience, but more precise predictions require analysis of motor and load speed/torque curves.
soft start, start current, reduced current, constant current
Can soft starters control an already rotating motor (flying load)?
Yes, soft starters can start motors that are already rotating.
In general, the faster the motor is still rotating, the shorter the start time will be.
If the motor is rotating in the reverse direction, it will be slowed to a standstill and then accelerate forwards.
No special wiring or soft starter setup is required. flying start, start delay, restart
What is "motor thermal capacity"?
A motor’s thermal capacity is the maximum time a motor can run at locked rotor current from cold. Thermal capacity is also referred to as "maximum locked rotor time" or "maximum DOL start time". This information is usually available from the motor datasheet. motor protection, thermal model, thermal capacity, MSTC, motor start time constant, maximum start time, motor overload
How is AuCom's's motor thermal model different from other forms of overload protection?
AuCom's motor thermal model offers precise motor protection normally only available from high-end motor protection relays.
- Protection is based on the motor's actual thermal capacity.
- Motor temperature is continually modeled.
- The thermal model accounts for different heating and cooling rates when the motor is in different operating states (starting, running or stopped).
- Both iron and copper losses are modeled.
The accuracy of the motor thermal model means the motor can be used to its maximum potential without nuisance tripping.
Thermal overload relays are imprecise because:
- The mass of the bimetal strips in the thermal overload is fixed and cannot be altered to match motor characteristics.
- They do not account for iron loss.
- They do not allow for different cooling rates at different stages of motor operation.
- The bimetal strips are affected by their ambient temperature, which is typically different to the motor’s ambient temperature.
- Adjustment is imprecise.
Inverse time-current and I2T electronic overloads offer limited protection because:
- The trip curves do not closely match motor heating.
- Inverse time-current protection does not account for motor temperature before the overload.
- They do not typically allow for differing cooling rates at different stages of motor operation.
- They do not account for iron loss.
- Adjustment is limited. motor protection, thermal model, thermal capacity, MSTC, motor start time constant, maximum start time, motor overload, time overcurrent, I2T
What are the key benefits of soft start?
Soft start enhances motor start performance in many ways including:
- smooth acceleration without the torque transients associated with electro-mechanical reduced voltage starters.
- voltage or current is applied gradually, without the voltage and current transients associated with electro-mechanical reduced voltage starters.
- lower start currents and/or shorter start times because constant current control gives higher torque as motor speed increases.
- easy adjustment of start performance to suit the specific motor and load.
- precise control over the current limit.
- consistent performance even with frequent starts.
- reliable performance even if load characteristics vary between starts (eg loaded or unloaded starts).
In addition to superior starting performance, soft starters also provide a range of features not available from other reduced voltage starters. This features include areas such as:
- soft stop (which helps eliminate water hammer)
- braking
- motor and system protection
- metering and monitoring
- operating history and event logs
- communication network integration
The extra features built into soft starters can reduce the overall installed cost of the equipment and reduce the long-term maintenance requirement. soft start, reduced voltage starting, features, benefits
How does soft start compare with star/delta starting?
Compared with star/delta starters, soft starters are much more flexible and provide a smooth start with no risk of transients.
Star/delta starters offer limited performance because:
- start torque cannot be adjusted to accommodate motor and load characteristics.
- there is an open transition between star and delta connection that results in damaging torque and current transients.
- they cannot accommodate varying load conditions (eg loaded or unloaded starts).
- they do not provide soft stop.
The main advantages of star/delta starters are:
- they may be cheaper than a soft starter.
- when used to start an extremely light load, they may limit the start current to a lower level than a soft starter. However, severe current and torque transients may still occur. soft start, comparison, star/delta
How does soft start compare to auto-transformer starting?
Compared with auto-transformer starters, soft starters are much more flexible and provide a much smoother start.
Auto-transformer starters offer limited performance because:
- they offer only limited ability to adjust start torque to accommodate motor and load characteristics.
- there are still current and torque transients associated with steps between voltages.
- they large and expensive.
- they are especially expensive if high start frequency is required.
- unable to accommodate changing load conditions. e.g. loaded or unloaded starts.
- unable to provide soft stop. soft start, comparison, auto-transformer
How does soft start compare to primary resistance starting?
Compared with primary resistence starters, soft starters are more flexible and reliable.
Primary resistance starters offer limited performance because:
- start torque cannot be fine-tuned to match motor and load characteristics.
- current and torque transients occur at each voltage step.
- they are large and expensive.
- liquid resistance versions require frequent maintenance.
- start performance changes as the resistance heats up. So multiple or restart situation are not well controlled.
- unable to accommodate changing load conditions. e.g. loaded or unloaded starts.
- they cannot provide soft stop. soft start, comparison, primary resistance, liquid resistance
Are all three phase soft starters the same?
No. There are different styles of soft starter which control the motor in different ways and offer different features.

These devices reduce torque shock at start but do not reduce start current. Also known as torque controllers, these devices must be used in conjunction with a direct on-line starter.

These devices eliminate torque transients and reduce motor start current. The uncontrolled phase has slightly higher current than the two controlled phases during motor starting. They are suitable for all but severe loads.

These devices control all three phases, providing the optimum in soft start control. Three phase control should be used for severe starting situations. soft start, advanced soft starter, digital soft starter, compact soft starter, torque controller, soft start controller