Manual de referencia

Manual de referencia

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D

I G I S TA RT e t

Reference guide

4491 en - 2012.06 / c

Contents

1 Introduction

1.1

General

1.2

Benefits of soft starters

1.3

Typical Applications

1.4

Different motor starting methods

1.5

What is the minimum start current with a soft starter?

1.6

Are all three phase soft starters the same?

2 Soft Start and Soft Stop Methods

2.1

Soft Start Methods

2.2

Stop Methods

2.3

Jog

3 Applying Soft Starters/System Design

3.1

Do I need to use a main contactor?

3.2

What are bypass contactors?

3.3

What is an inside delta connection?

3.4

How do I replace a star/delta starter with a soft starter?

3.5

How do I use power factor correction with soft starters?

3.6

How do I ensure Type 1 circuit protection?

3.7

How do I ensure Type 2 circuit protection?

3.8

How do I select cable when installing a soft starter?

3.9

What is the maximum length of cable run between a soft starter and the motor?

3.10 How do two-speed motors work and can I use a soft starter to control them?

3.11 Can one soft starter control multiple motors separately for sequential starting?

3.12 Can one soft starter control multiple motors for parallel starting?

3.13 Can slip-ring motors be started with a soft starter?

3.14 Can soft starters reverse the motor direction?

3.15 How are soft starters installed in a IP54 type enclosure?

3.16 Can soft starters control an already rotating motor (flying load)?

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3.17 Brake

3.18 What is soft braking and how is it used?

4 Choosing Soft Starters

4.1

Application selection

4.2

Starter sizing

4.3

Utilisation Codes

4.4

Typical Motor FLCs

4.5

Using soft starters with large motors

5 D2 and D3 Digistart Soft Starter Selection

5.1

Three step process

5.2

Starter selection

5.3

Application selection

5.4

Starter sizing

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1. Introduction

1.1 General

Studies have shown that most of the motors employed in industrial applications use no form of control other than simple electromechanical switching. This results in increased machine wear as rapid acceleration causes damaging torque transients and high peak currents. Soft starters solve this problem through controlling the application of current during acceleration and deceleration.

In applications where motor speed can be varied, significant energy savings can be realised by using variable speed drives. However in fixed speed applications soft starters are still the most economic solution.

The purpose of this guide is to outline the principle benefits of using soft starters compared to other electro-mechanical start methods, and to discuss the advantages and disadvantages of the various soft start methods. This guide also covers some of the advanced functionality that can be found in today’s modern soft starters as well as the considerations when choosing and sizing soft starters.

1.2 Benefits of soft starters

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 includes areas such as:

► Soft stop

(which helps eliminate water hammer)

► Metering and monitoring

► Braking ► Operating history and event logs

► Motor and system protection ► Communication network

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1.3 Typical Applications

Soft starters can offer benefits for almost all motor starting applications. Typical advantages are highlighted below.

Table 1-1 Typical soft start applications

Pumps

► Minimised hydraulic shock in pipelines during start and stop.

► Reduced starting current.

► Minimised mechanical stress on motor shaft.

► Phase rotation protection prevents damage from reverse pump rotations.

Conveyor Belts

► Controlled soft start without mechanical shocks, e.g. bottles on a belt do not fall over during starting, minimised belt stretch, reduced counterbalance stress.

► Controlled stop without mechanical shock (soft stop).

► Optimum start performance even with varying starting loads (e.g. coal conveyors start loaded or unloaded).

► Extended mechanical lifetime.

► Maintenance-free.

Centrifuges

► Smooth application of torque prevents mechanical stress.

► Reduced starting times over star/delta starting.

Ski Lifts

► Jerk-free acceleration increases skier comfort and prevents swinging T-bars etc.

► Reduced starting current allows starting of large motors on a weak power supply.

► Smooth and gradual acceleration whether the ski lift is lightly or heavily loaded.

► Phase rotation protection prevents operation in reverse direction.

6

Compressors

► Reduced mechanical shock extends the life of the compressor, couplings and motor.

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

► Phase rotation protection prevents operation in reverse direction.

Fans

► Extended coupling life though reduced mechanical shock.

► Reduced start current enables large fans to be started when maximum power capacity is limited.

► Phase rotation protection prevents operation in reverse direction.

Mixers

► Gentle rotation during start-up reduces mechanical stress.

► Reduced starting current.

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1.4 Different motor starting methods

1.4.1 Star/Delta

A star/delta start configuration comprises a six terminal motor that is delta connected at the supply voltage. The star/delta starter employs three contactors to initially start the motor in a star connection, then after a period of time, to reconnect the motor to the supply in a delta connection. While in the star connection, the voltage across each winding is reduced by a factor of the square root of 3. This results in the current and torque being one third of the full DOL voltage current and torque whilst in star configuration. If there is insufficient torque available while connected in star, the motor will only accelerate to partial speed. When the timer operates (set normally from 5-10 seconds), the motor is disconnected from the supply and reconnected in delta resulting in full voltage start currents and torque.

Figure 1-1 Star/delta connection

1 2 3

1

Main contactor

2

Thermal overload

3

Motor (three-phase)

4

Delta contactor

5

Star contactor

4 5

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.

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1.4.2 Auto-transformer

Auto-transformer starters use an auto-transformer to reduce the voltage during the start period. The transformer has a range of output voltage taps that can be used to set the start voltage. The motor current is reduced by the start voltage reduction, and further reduced by the transformer action resulting in a line current less than the actual motor current. The initial start voltage is set by tap selection, and the start time is controlled by a timer. If the start voltage is too low, or the start time incorrectly set, the transition to full voltage will occur with the motor at less than full speed, resulting in a high current and torque step.

Figure 1-2 Auto-transformer connection

1 2

1

Run contactor

2

Thermal overload

3

Start contactor (A)

4

Start contactor (B)

5

Auto-transformer

3 5 4

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 are large and expensive.

► They are especially expensive if high start frequency is required.

► They cannot accommodate changing load conditions. eg. loaded or unloaded starts.

► They cannot provide soft stop.

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1.4.3 Primary resistance starters

For primary resistance starting, resistors are connected in series with each phase, between the isolation contactor and the motor. The voltage drop across the resistors results in a reduced voltage applied to the motor, thus reducing start current and torque.The reduced voltage start time is controlled by a preset timer. If the time is too short, the motor will not have achieved full speed before the resistors are bridged. Start voltage is determined by the resistors used. If the resistance is too high there will be insufficient torque to accelerate the motor to full speed.

Figure 1-3 Primary resistance connection

2

1

Line contactor

2

Run contactor

3

Thermal overload

4

Start resistors

1 4 3

Compared with primary resistance 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.

► They cannot accommodate changing load conditions (eg loaded or unloaded starts).

► They cannot provide soft stop.

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1.4.4 Variable speed drives

A variable speed drive (VSD) is a device that can control the speed of an electric motor by controlling the frequency and voltage of the electrical power supplied to it. When a drive starts a motor, it initially applies a low frequency and voltage to the motor thus allowing high inrush currents to be avoided.

As drives can be used to control the speed of the motor substantial energy savings are possible when the motor can be run at a reduced speed.

If the application cannot be run at part speed then a soft starter will be a more energy efficient solution compared to a drive, at least where a contactor is used to bypass the starter once the motor is at full speed. In such applications a soft starter will require less capital outlay compared to a drive.

1.5 What is the minimum start current with 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.

Figure 1-4 Successful soft start

1 0

700%

600%

500%

400%

300%

200%

100%

Full voltage current

Current limit

200%

Full voltage start torque

Acceleration torque

100%

Torque output at current limit

Load Torque curve

10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Speed (% Full speed) www.leroy-somer.com

Figure 1-5 Unsuccessful soft start

700% Full voltage current

600%

500%

400%

300%

200%

100%

Limite du courant

Stall

Torque output at current limit

Full voltage start torque

Acceleration torque

Load Torque curve

200%

100%

10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Speed (% Full speed)

1.6 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.

Single phase control

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.

Two phase control

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. It is Digistart D2 configuration.

Three phase control

These devices control all three phases, providing the optimum in soft start control. Three phase control should be used for severe starting situations. It is Digistart D3 configuration. www.leroy-somer.com

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2. Soft Start and Soft Stop Methods

2.1 Soft Start Methods

Soft starters offer a variety of methods to control motor starting. Each soft start method uses a different primary control parameter.

Table 2-1 Soft start methods

Soft Start Method

Timed Voltage Ramp

Parameter Controlled Performance Parameters Influenced

Voltage Start current, start torque, acceleration

Constant Current

Torque Control

Current

Torque

Start torque, acceleration

Start current, acceleration

Adaptive Acceleration Control Acceleration Start current, start torque

Best results are obtained by selecting the soft start method that directly controls the parameter of most importance for the application. Typically soft starters are used to limit motor start current or control load acceleration and/or deceleration.

2.1.1 Timed Voltage Ramp (TVR) Starting

Timed voltage ramp (TVR) was the earliest form of soft starting. TVR slows the application of voltage, which reduces the start current. This reduces start torque and slows the motor’s rate of acceleration.

The main benefits of voltage control are:

► Reduced start current and start torque.

► Elimination of mechanical and electrical transients.

TVR soft starting is not suitable for high inertia loads (such as fans), which require a high level of voltage to accelerate the load.

TVR soft starting is widely used in open loop (voltage controlling) soft starters. TVR soft starting is not commonly found in closed loop soft starters, which monitor and control current.

Figure 2-1 TVR soft start

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2

1

1

Initial start voltage

2

Full voltage

3

Initial start time

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Time www.leroy-somer.com

2.1.2 Current limit starting

With current limit starting, the soft starter delivers voltage to the motor until it reaches a specified current level, then pauses the voltage ramp. When the current drops, the voltage ramp continues. This keeps start current within the required limit, although the motor’s actual current level varies throughout the start.

This can be useful for generator set applications where the supply is limited.

2.1.3 Constant current

With constant current starting, the current is raised from zero to a specified level and keeps the current stable at that level until the motor has accelerated.

Constant current starting is ideal for applications where the start current must be kept below a particular level.

Figure 2-2 Constant current soft start

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700%

600%

500%

400%

300%

200%

100%

1

2

1

Initial current

2

Current limit

3

Full voltage current

10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Rotor speed (% full speed)

2.1.4 Current Ramp

Current ramp soft starting raises the current from a specified starting level (1) to a maximum limit (3), over an extended period of time (2).

Current ramp starting can be useful for applications where:

► The load can vary between starts (for example a conveyor which may start loaded or unloaded). Set the initial current to a level that will start the motor with a light load, and the current limit to a level that will start the motor with a heavy load.

► The load breaks away easily, but starting time needs to be extended (for example a centrifugal pump where pipeline pressure needs to build up slowly).

► The electricity supply is limited (for example a generator set), and a slower application of load will allow greater time for the supply to respond. www.leroy-somer.com

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Figure 2-3 Current ramp soft start

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700%

600%

500%

400%

300%

200%

100%

1

2

3

1

Initial current

2

Start ramp time

3

Current limit

4 Full voltage current

10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Rotor speed (% full speed)

2.1.5 Torque Control

Torque control is promoted as a method of providing a more linear speed ramp in soft starters. By providing a constant acceleration torque, torque control will allow the motor to speed up or slow down in a linear fashion.

Torque control monitors current and power factor, and adjusts the output power of the motor to make the torque difference between the motor and load as constant as possible.

Torque control is suitable for applications where:

► Load torque is constant (linear) throughout the start.

► Load torque is constant between starts.

2.1.6 Adaptive Control for Starting

Adaptive Acceleration Control is a new intelligent motor control technique. In an adaptive control soft start, the soft starter adjusts the current in order to start the motor within a specified time and using a selected acceleration profile.

Every application has a particular starting profile, based on characteristics of the load and the motor. Adaptive Acceleration Control offers three different starting profiles, to suit the requirements of different applications. Selecting a profile that matches the inherent profile of the application can help smooth out acceleration across the full start time. Selecting a dramatically different Adaptive Control profile can somewhat neutralise the inherent profile.

The soft starter monitors the motor’s performance during each start, to improve control for future soft starts.

Note:

Adaptive Control controls the motor’s speed profile, within the programmed time limit. This may result in a higher level of current than traditional control methods.

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Figure 2-4 Adaptive Control soft start

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60%

50%

40%

30%

20%

10%

0%

100%

90%

80%

70%

1

2

Time

3

1

Early acceleration

2

Constant acceleration

3

Late acceleration

4

Start time

How to Select the Adaptive Acceleration Control Start Profile

The best profile will depend on the exact details of each application. If you have particular operational requirements, discuss details of your application with your local supplier.

Some loads, such as submersible pumps, should not be run at slow speeds. An early acceleration profile will raise the speed quickly, then control acceleration through the rest of the start.

Table 2-2 Adaptive Control profiles for common applications

Application Parameter

Pump Centrifugal

Adaptive Start Profile

Adaptive Stop Profile

Pump Submersible

Fan Undamped

Conveyor

Adaptive Start Profile

Adaptive Stop Profile

Adaptive Start Profile

Start Mode

Current Limit

Adaptive Stop Profile

Suggested value

Early Acceleration

Late Deceleration

Early Acceleration

Late Deceleration

Constant Acceleration

Constant Current

400%

Constant Deceleration www.leroy-somer.com

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2.1.7 Kickstart

Kickstart provides a short boost of extra torque at the beginning of a start, and can be used in conjunction with current ramp or constant current starting.

Kickstart can be useful to help start loads that require high breakaway torque but then accelerate easily (for example flywheel loads such as presses).

Figure 2-5 Current ramp soft start with kickstart

700%

600%

500%

400%

300%

200%

100%

6

2

1

4

3

5

1

Kickstart level

2

Kickstart time

3

Initial current

4

Start ramp time

5

Current limit

6

Full voltage current

10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Rotor speed (% full speed)

2.2 Stop Methods

Soft starters offer a variety of methods for the control of motor stopping.

Table 2-3 Soft stop methods

Stop Method

Coast To Stop

TVR Soft Stop

Adaptive Control

STV Stop

Brake

Performance Result

Natural load run down

Extended run down time

Extended run down time according to selected deceleration profile

Extended run down time

Reduced run down time

Soft starters are often used in pumping applications to eliminate the damaging effects of fluid hammer. Adaptive Control should be the preferred stop method for these applications.

2.2.1 Coast to Stop

Coast to stop lets the motor slow at its natural rate, with no control from the soft starter. The time required to stop will depend on the type of load.

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2.2.2 Timed Voltage Ramp (TVR) Soft Stop

Timed voltage ramp reduces the voltage to the motor gradually over a defined time. The load may continue to run after the stop ramp is complete.

Timed voltage ramp stopping can be useful for applications where the stop time needs to be extended, or to avoid transients on generator set supplies.

Figure 2-6 TVR soft stop

100%

90%

80%

70%

60%

50%

40%

30%

20%

10%

0%

1

Time

1

Stop time

2.2.3 Adaptive Control for Stopping

In an adaptive control soft stop, the soft starter controls the current in order to stop the motor within a specified time and using a selected deceleration profile. Adaptive Deceleration

Control can be useful in extending the stopping time of low inertia loads.

Note:

Adaptive control does not actively slow the motor down and will not stop the motor faster than a coast to stop. To shorten the stopping time of high inertia loads, use brake.

Every application has a particular stopping profile, based on characteristics of the load and the motor. Adaptive Deceleration Control offers three different stopping profiles. Choose the adaptive control profile that best matches your application requirements.

Figure 2-7 Adaptive Deceleration Control soft stop

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30%

20%

10%

0%

100%

90%

80%

70%

60%

50%

40%

1

2

3

1

2

3

4

Early deceleration

Constant deceleration

Late deceleration

Stop time

Time

The advent of Adaptive Control has made solving the problem of fluid hammer easier as the most appropriate deceleration profile can be selected for the application.

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Table 2-4 Adaptive Deceleration Control soft stop profiles

Adaptive Stop Profile Application

Late Deceleration

High head systems where even a small decrease in motor/pump speed results in a rapid transition between forward flow and reverse flow.

Constant Deceleration

Early Deceleration

Low to medium head, high flow applications where the fluid has high momentum.

Open pump systems where fluid must drain back through the pump without driving the pump in reverse.

Note:

Pump stopping: The hydraulic characteristics of pump systems vary considerably. This variation means the ideal deceleration profile and stop time will vary from application to application. The table provides guidelines on selecting between Adaptive Control deceleration profiles, but we recommend testing the three profiles to identify the best profile for the application.

How to Select the Adaptive Deceleration Control Stop Profile

The best profile will depend on the exact details of each application. If you have particular operational requirements, discuss details of your application with your local supplier.

Note:

Adaptive Control controls the motor’s speed profile, within the programmed time limit. This may result in a higher level of current than traditional control methods.

2.3 Jog

Jog runs the motor at reduced speed, to allow alignment of the load or to assist servicing.

The motor can be jogged in either forward or reverse direction.

The maximum available torque depends on the soft starter. Check the soft starter User

Guide for details.

Figure 2-8 Jog operation

100%

90%

80%

70%

60%

50%

40%

30%

20%

10%

0%

1

2

3

1

Motor FLT

2

Jog forward maximum torque

3

Jog feverse maximum torque

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3. Applying Soft Starters/System Design

3.1 Do I need to use a main contactor?

While soft starters can be installed with or without a main contactor, we strongly recommend their use for the following reasons:

► It may be required to meet local electrical regulations.

► It 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.

Main contactors should be AC3 rated for the motor FLC.

Figure 3-1 Installation of a starter with internal bypass and main contactor

KM1 F1

1/L1

3/L2

5/L3

E

2/T1

4/T2

6/T3

COM1

RLO1

KM1

KM1

Main contactor

F1

Semiconductor fuses

(optional) www.leroy-somer.com

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3.2 What are bypass contactors?

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. SCRs dissipate approximately 4.5 watts per running ampere if not bypassed.

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.

Non-bypassed models have dedicated bypass terminals, which allow the soft starter to continue providing protection and monitoring functions even when bypassed via an external bypass contactor. The bypass contactor must be connected to the bypass terminals and controlled by the soft starter’s run output (terminals COM2, RLO2).

Figure 3-2 Installation with external bypass contactor (starter without internal bypass)

KM2

KM1

Main contactor

KM2

Bypass contactor

F1

Semiconductor fuses

(optional)

KM1

1/L1

L1B

3/L2

L2B

5/L3

L3B

E

2/T1

F1

4/T2

6/T3

2 0

COM1

RLO1

COM2

KM1

RLO2

KM2 www.leroy-somer.com

3.3 What is an inside delta connection?

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.

Figure 3-3 Inside delta installation, internally bypassed

KM1

F1

1/L1

3/L2

4/L3

L3B

E

2/T1

4/T2

6/T3

COM1

RLO1

KM1

U1(1)

V1(2)

W1(3)

U2(4)

V2(5)

W2(6)

KM1

F1

Main contactor

Semiconductor fuses

(optional) www.leroy-somer.com

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Figure 3-4 Inside delta installation, externally bypassed

KM2

KM1

1/L1

L1B

3/L2

L2B

5/L3

L3B

E

2/T1

4/T2

6/T3

F1

U1(1)

V1(2)

W1(3)

U2(4)

V2(5)

W2(6)

COM1

RLO1

COM2

KM1

KM1

Main contactor

KM2

Bypass contactor

F1

Semiconductor fuses

(optional) RLO2

KM2

3.4 How do I replace a star/delta starter with a soft starter?

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.

3.5 How do I use power factor correction with soft starters?

Individual power factor correction capacitors can be used with soft starters, provided 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

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3.6 How do I ensure Type 1 circuit protection?

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.

Table 3-1 Type 1 circuit protection

Starter type Protection Type

Compact soft starter

Advanced soft starter

Fuse (non time delayed)

Fuse (time delayed)

MCCB*

Fuse (non time delayed)

Fuse (time delayed)

MCCB*

* Consult the manufacturer’s specifications

Fuse Rating (% Motor FLC)

< 350% FLC

15 seconds

175%

> 350% FLC

15 seconds

200%

150% 175%

150- 200%

150%

125%

150- 200%

Maximum fuse ratings for Type 1 motor protection are specified in UL and IEC standards.

Fuse

Fuse (non time delayed)

Fuse (time delayed)

Rating (% Motor FLC)

300%

175%

3.7 How do I ensure Type 2 circuit protection?

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 I 2 t< the I 2 t 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 User Guide for semiconductor fuse recommendations.

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2 3

3.8 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. Typically:

► Supply cable rating

> nominal fuse/MCCB rating

> motor FLC x 1.2

► 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 (including grouping, ambient temperature and single or parallel cabling). Always follow the manufacturer’s instructions.

3.9 What is the maximum 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 long cable runs. Consult the soft starter manufacturer for advice; you will need to provide details about mains voltage, mains frequency and the soft starter model.

3.10 How do two-speed motors 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. The complete connection diagram is available in section 10 of Digistart D3 user guide, ref.4259.

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

PAM (Pole Amplitude Modulated) motors alter the speed by effectively changing the stator frequency using external winding configuration. Soft starters are not suitable for use with this type of two-speed motor.

2 4 www.leroy-somer.com

3.11 Can one soft starter control multiple motors separately 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, each motor must have a separate main contactor, bypass contactor and overload protection

The soft starter must be suitably rated for the total start duty.

3.12 Can one soft starter control multiple motors for parallel starting?

Yes. The circuit configuration and soft starter selection depends on the application.

Each motor must have its own overload protection.

If the motors are the same size and are mechanically coupled, a constant current soft starter can be used.

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.

The combined motor FLCs must not exceed the soft starter FLC.

3.13 Can slip-ring motors 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.

R (per phase) = 0.2 x

V

R

√3 x I

R

Rotor resistance (R) can be sized using the following formula:

20% x motor kW

Power (per phase) =

3

Where V

R

= open circuit rotor voltage

I

R

= full load rotor current www.leroy-somer.com

2 5

Figure 3-5 Slip-ring motor

KM2

F1

1

1/L1

3/L2

5/L3

E

2/T1

R1

4/T2

6/T3

2

KM1

COM3

RLC3

RLO3

3

KM1

1

2

3

Three-phase supply

Slip-ring induction motor

Relay outputs

KM1 Changeover contactor

KM2 Main Contactor

F1 Semiconductor fuses (optional)

R1 Rotor resistance (external)

2 6 www.leroy-somer.com

3.14 Can soft starters reverse the 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 (as Digistart D3) 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.

Figure 3-6 Installation with forward and reversing contactors

FWD

Soft Starter

REV

3.15 How are soft starters installed in a IP54 type 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 and switchgear). The enclosure should be protected from direct sunlight to prevent external heating.

To minimise heating, soft starters are best installed in bypassed configuration.

3.16 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 rotating in the forward direction, 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. Allow for the extended start time when rating the soft starter.

No special wiring or soft starter setup is required.

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2 7

3.17 Brake

When brake is selected, the soft starter uses DC injection to slow the motor.

Soft starter braking:

► Does not require the use of a DC brake contactor.

► Controls all three phases so that the braking currents and associated heating are evenly distributed through the motor.

Braking has two stages:

1. Pre-brake: provides an intermediate level of braking to slow motor speed to a point

where full brake can be operated successfully (approximately 70% speed).

2. Full brake: brake provides maximum braking torque but is ineffective at speeds greater than approximately 70%.

CAUTION

If the brake torque is set too high, the motor will stop before the end of the brake

time and the motor will suffer unnecessary heating which could result in damage.

Careful configuration is required to ensure safe operation of the starter and motor.

When using DC brake, the mains supply must be connected to the soft starter

(input terminals L1, L2, L3) in positive phase sequence.

3.18 What is soft braking and how is it used?

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 or output 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.

The complete connection diagram is available in section 10 of Digistart D3 user guide, ref.4259.

2 8 www.leroy-somer.com

4. Choosing Soft Starters

4.1 Application selection

Different applications typically require different levels of start current.

The level of start current affects how many starts the soft starter can complete per hour.

Some soft starters may not offer high enough start current for extreme applications.

Table 4-1 Typical start current requirements

Application

Agitator

Atomiser

Bottle Washer

x

Centrifuge

Chipper

Compressor - Reciprocal (loaded)

Compressor - Reciprocal (unloaded)

Compressor - Screw (loaded)

Compressor - Screw (unloaded)

Conveyor - Belt

Conveyor - Roller

Conveyor - Screw

Crusher - Cone

Crusher - Jaw

Crusher - Rotary

Crusher - Vertical Impact

Debarker

Dryer

Dust Collector

Edger

Fan - Axial (damped)

Fan - Axial (un-damped)

Fan - Centrifugal (damped)

Fan - Centrifugal (un-damped)

x x x x x x x x x x x x x x x x x x x x x x x

Application

Fan - High Pressure

Grinder

Hydraulic Power Pack

Mill

Mill - Ball

Mill - Hammer

Mill - Roller

Mixer

Pelletiser

Planer

Press

Pump - Bore

x

Pump - Centrifugal

Pump - Positive Displacement

Pump - Slurry

Re-pulper

Rotary Table

Sander

Saw - Bandsaw

Saw - Circular

Separator

Shredder

Slicer

x

Tumbler

x x x x x x x x x x x x x x x x x x x x x x

www.leroy-somer.com

2 9

4.2 Starter sizing

The soft starter must be the correct size for the motor and the application. Select a soft starter that has a current rating at least equal to the motor’s full load current (nameplate or technical guide) rating, at the start duty.

4.3 Utilisation Codes

4.3.1 AC53a utilisation code

The AC53a Utilisation Code (from IEC 947-4-2) 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 utilisation code. The soft starter may have a higher or lower current rating in different operating conditions.

Figure 4-1 AC53a utilisation code

351A : AC-53a 3.5

15 : 50 6

Starts per hour

On-load duty cycle (%)

Start time (s)

Start current (multiple of motor full load current)

Starter current rating (A)

Starter current rating: The full load current rating of the soft starter given the parameters detailed in the remaining sections of the utilisation code.

Start current: The maximum available start current.

Start time: The maximum allowable start time.

On-load duty cycle (%): The maximum percentage of each operating cycle that the soft starter can operate.

Starts per hour: The maximum allowable number of starts per hour.

3 0 www.leroy-somer.com

Figure 4-2 AC53a duty cycle

2 5 6

350%

4

100%

1

Operating cycle =

7

3

Time

Start time + Running time

Start time + Running time + Off time

1

Start current

2

Start time

3

On-load time

4

Starts per hour

5

Running time

6

Off time

7

Motor FLC www.leroy-somer.com

3 1

4.3.2 AC53b Utilisation Code

The AC53b utilisation code (from IEC 947-4-2) 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 utilisation code. The soft starter may have a higher or lower current rating in different operating conditions.

Figure 4-3 AC53b utilisation code

351A : AC-53a 3.5

15 : 50 6

Starts per hour

On-load duty cycle (%)

Start time (s)

Start current (multiple of motor full load current)

Starter current rating (A)

Starter current rating: The full load current rating of the soft starter given the parameters detailed in the remaining sections of the utilisation code.

Start current: The maximum available start current.

Start time: The maximum allowable start time.

Off time: The minimum allowable time between the end of one start and the beginning of the next start.

Figure 4-4 AC53b duty cycle

350%

100%

1

2 3

4

1

Start current

2

3

4

Start time

Off time. It includes the time during which the starter is running with bypassed

SCRs (not passing current)

Motor FLC

Time

3 2 www.leroy-somer.com

4.4 Typical Motor FLCs

If you don’t have accurate information on your motor’s start current characteristics, the table below can help you estimate the likely full load current for a particular motor size. This information can help when choosing a soft starter, but will not provide an optimised solution because the characteristics of different motors can vary considerably.

Table 4-2 Typical motor FLCs kW

300

315

335

355

250

257

280

295

160

185

200

220

132

140

147

150

22

25

30

37

7.5

11

15

18.5

45

55

75

90

110

600

650

700

750

800

850

900

950

1000

450

475

500

560

375

400

425

445

Motor Power

HP

410

430

450

480

340

350

380

400

220

250

270

300

180

190

200

205

30

35

40

50

10

15

20

25

60

75

100

125

150

800

870

940

1000

1070

1140

1250

1275

1340

610

645

680

760

500

545

580

600

220-230 V

800

826

900

948

980

990

1100

1150

520

595

626

700

425

450

472

483

75

85

103

126

27

39

52

64

150

182

240

295

356

1875

2031

2187

2343

2499

2656

2812

2968

3124

1180

1250

1330

1400

1410

1490

1570

1750

Current rating at different voltages

380-400 V

565

584

620

636

460

475

510

546

300

342

370

408

245

260

273

280

44

52

60

72

15.5

22

30

37

85

105

138

170

205

1085

1176

1266

1357

1447

1537

1628

1718

1809

670

710

760

790

800

850

900

1000

440 V

481

505

518

549

401

412

450

473

256

295

321

353

215

227

236

246

13.7

20.1

26.5

32.8

39

45.3

51.5

64

76

90

125

146

178

937

1015

1093

1172

1250

1328

1406

1484

1562

690

730

780

860

575

611

650

680

500 V

420

445

472

500

360

365

400

416

220

263

281

310

187

200

207

210

12

18.4

23

28.5

33

39.4

45

55

65

80

105

129

156

825

894

962

1031

1100

1168

1237

1306

1375

608

645

680

760

527

540

574

595

660-690 V

325

337

355

370

274

280

305

320

170

200

215

235

140

145

152

159

8.9

14

17.3

21.3

25.4

30.3

34.6

42

49

61

82

98

118

625

677

729

781

833

885

937

989

1041

460

485

515

570

395

410

445

455 www.leroy-somer.com

3 3

4.5 Using soft starters with large motors

There are several factors to consider when planning to use a soft starter with a large motor

(> 300 kW).

► Larger motors have copper rotor bars, not aluminium. This reduces effective starting

torque and can increase rotor inertia.

► Increased rotor inertia may require a longer start time.

► The start current may need to be greater than for a smaller motor, by 50% to 100% of motor FLC.

► Starts per hours are generally limited by the motor’s duty cycle rating.

3 4 www.leroy-somer.com

5. D2 and D3 Digistart Soft Starter Selection

5.1 Three step process

To select the best soft starter for your application, you can use the tables below or use the

Digistart Size soft starter selection software.

1. Identify the features required. This will help you choose the best starter to suit your application.

2. Identify your application. This will tell you the start current required.

3. Calculate which starter model matches your requirement.

5.2 Starter selection

You need to select a starter that offers the features you require for the application. This may include:

► the best start method for the application

► input and output options to interface with external equipment

► serial communication control

► specific protections

5.2.1 Key features

Table 5-1 Digistart features

Feature Digistart D2 Digistart D3

Selectable soft starting profiles

Adaptive Acceleration Control

Kickstart

Constant current

Current ramp

Selectable soft stopping profiles

Adaptive Deceleration Control

Timed voltage ramp soft stop

Brake

Extensive input and output options

Remote control inputs

Relay outputs

Analog output

Built-in PT100 RTD input

Easy-to-read display with comprehensive feedback

Removable keypad Optional Remote Keypad

Multi-language feedback

Date and time stamped event logging

Operational counters

Performance monitoring

x x x x x x x x x x

2 x fixed 3 x fixed, 2 x programmable

1 x fixed, 1 x programmable 1 x fixed, 3 x programmable current

1 x programmable

1 x fixed

x x x

number of starts, hours run, kWh current, voltage, power factor, kWh www.leroy-somer.com

3 5

Feature continued Digistart D2

Models for all connection requirements

Current range

Mains voltage

Control voltage

Internal bypassed

Motor connection

Optional features for advanced applications

Input/output expansion

DeviceNet, Modbus or Profibus communication interfaces

RTD / PT100

Fully customisable protection - See overleaf

18 A to 200 A (nominal)

200 Vac to 440 Vac or

200 Vac to 575 Vac

110 to 240 Vac

380 to 440 Vac

All models

In-line

x x

Digistart D3

23 A to 1600 A (nominal)

200 VAC to 440 Vac or

380 VAC to 690 Vac

110 to 210 Vac

220 to 440 Vac

Up to 1000 A

In-line or inside delta

x x x

5.2.2 Protections

Soft starters can offer a wide range of protections for the load, motor and system. This can eliminate external motor protection devices and reduce panel space, cost and installation time.

Table 5-2 Digistart protection options

Trip Name

Excess start time

Motor overload (thermal model)

Motor thermistor

Current imbalance

Supply Frequency

Phase sequence

Instantaneous overcurrent

Heatsink overtemperature

Incorrect motor connection

Input trip

FLC too high (FLC out of range)

Starter communication (between module and soft starter)

Network communication (between module and network)

Internal fault

Ground fault (requires RTD/PT100 and Ground Fault card)

Phase loss

Phase shorted

Digistart D2

x x x x x x x x

Digistart D3

x x x x x x x x x x x x x x x x x

3 6 www.leroy-somer.com

Trip Name continued

Motor 2 overload (thermal model)

Time-overcurrent (Bypass overload)

RTD/PT100 overtemperature

Thermistor circuit

Overpower

Underpower

Digistart D2

x

Digistart D3

x x x x x x

5.3 Application selection

Different applications typically require different levels of start current.

The level of start current affects how many starts the soft starter can complete per hour.

Some soft starters may not offer high enough start current for extreme applications. Refer to table 4-1 Typical Start Current Requirements on page 29.

5.4 Starter sizing

The soft starter must be the correct size for the motor and the application.

Select a soft starter that has a current rating at least equal to the motor’s full load current

(nameplate) rating, at the start duty.

5.4.1 Digistart current ratings

Table 5-3 Digistart D2 current ratings

D2-1x-018

D2-1x-042

D2-1x-060

D2-1x-085

D2-1x-100

D2-1x-140

D2-1x-170

D2-1x-200

40 °C

18 A

42 A

60 A

AC53b 4-6:354

< 1000 metres

50 °C

17 A

40 A

55 A

40 °C

85 A

100 A

140 A

170 A

200 A

AC53b 4-6:594

< 1000 metres

50 °C

78 A

100 A

133 A

157 A

186 A

40 °C

17 A

36 A

49 A

AC53b 20:340

< 1000 metres

50 °C

15 A

33 A

45 A

40 °C

73 A

96 A

120 A

142 A

165 A

AC53b 4-20:580

< 1000 metres

50 °C

67 A

87 A

110 A

130 A

152 A www.leroy-somer.com

3 7

Table 5-4 Digistart D3 current ratings - in-line connection, bypassed operation

Model

D3-1x-0023-B

D3-1x-0043-B

D3-1x-0053-B

D3-1x-0076-B

D3-1x-0097-B

D3-1x-0105-B

D3-1x-0145-B

D3-1x-0170-B

D3-1x-0200-B

D3-1x-0220-B

D3-1x-0255-B

D3-1x-0350-B

D3-1x-0425-B

D3-1x-0500-B

D3-1x-0700-B

D3-1x-0820-B

D3-1x-0920-B

D3-1x-1000-B

D3-1x-0255-N

D3-1x-0360-N

D3-1x-0430-N

D3-1x-0650-N

D3-1x-0790-N

D3-1x-0930-N

D3-16-1200-N

D3-16-1410-N

D3-16-1600-N

Note:

AC53b 3.0-10:350

40°C <1000 metres

23 A

43 A

53 A

AC53b 3.0-10:590

40°C <1000 metres

76 A

97 A

105 A

145 A

170 A

200 A

220 A

255 A

350 A

425 A

500 A

700 A

820 A

920 A

1000 A

255 A

360 A

430 A

650 A

790 A

930 A

1200 A

1410 A

1600 A

AC53b 3.5-15:345

40°C <1000 metres

20 A

37 A

53 A

AC53b 3.5-15:585

40°C <1000 metres

64 A

82 A

105 A

123 A

145 A

189 A

210 A

231 A

306 A

371 A

445 A

592 A

705 A

804 A

936 A

231 A

360 A

430 A

650 A

790 A

930 A

1200 A

1410 A

1600 A

AC53b 4.0-20:340

40°C <1000 metres

17 A

31 A

46 A

AC53b 4.0-20:580

40°C <1000 metres

55 A

69 A

95 A

106 A

121 A

160 A

178 A

201 A

266 A

321 A

383 A

512 A

606 A

684 A

796 A

201 A

310 A

368 A

561 A

714 A

829 A

1200 A

1319 A

1600 A

“B” models integrate internal bypass contactors in standard.For models D3-1x-0255-N to D3-16-1600-N these ratings are valid only when externally bypassed using a suitable contactor.

AC53b 4.5-30:330

40°C <1000 metres

15 A

26 A

37 A

AC53b 4.5-30:570

40°C <1000 metres

309 A

455 A

579 A

661 A

1071 A

1114 A

1353 A

276 A

326 A

438 A

516 A

571 A

664 A

176 A

263 A

47 A

58 A

78 A

90 A

97 A

134 A

148 A

176 A

230 A

3 8 www.leroy-somer.com

Table 5-5 Digistart D3 current ratings - inside delta connection, bypassed operation

Model

D3-1x-0023-B

D3-1x-0043-B

D3-1x-0053-B

D3-1x-0076-B

D3-1x-0097-B

D3-1x-0105-B

D3-1x-0145-B

D3-1x-0170-B

D3-1x-0200-B

D3-1x-0220-B

D3-1x-0255-B

D3-1x-0350-B

D3-1x-0425-B

D3-1x-0500-B

D3-1x-0700-B

D3-1x-0820-B

D3-1x-0920-B

D3-1x-1000-B

D3-1x-0255-N

D3-1x-0360-N

D3-1x-0430-N

D3-1x-0650-N

D3-1x-0790-N

D3-1x-0930-N

D3-16-1200-N

D3-16-1410-N

D3-16-1600-N

Note:

AC53b 3.0-10:350

40°C <1000 metres

34 A

64 A

79 A

AC53b 3.0-10:590

40°C <1000 metres

114 A

145 A

157 A

217 A

255 A

300 A

330 A

382 A

525 A

638 A

750 A

1050 A

1230 A

1380 A

1500 A

382 A

540 A

645 A

975 A

1185 A

1395 A

1800 A

2115 A

2400 A

AC53b 3.5-15:345

40°C <1000 metres

30 A

59 A

79 A

AC53b 3.5-15:585

40°C <1000 metres

96 A

123 A

157 A

184 A

217 A

283 A

315 A

346 A

459 A

557 A

668 A

889 A

1058 A

1206 A

1404 A

346 A

540 A

645 A

975 A

1185 A

1395 A

1800 A

2115 A

2400 A

AC53b 4.0-20:340

40°C <1000 metres

26 A

51 A

69 A

AC53b 4.0-20:580

40°C <1000 metres

83 A

104 A

143 A

159 A

181 A

241 A

268 A

302 A

399 A

482 A

575 A

768 A

910 A

1026 A

1194 A

302 A

465 A

552 A

842 A

1071 A

1244 A

1800 A

1979 A

2400 A

“B” models integrate internal bypass contactors in standard.For models D3-1x-0255-N to D3-16-1600-N these ratings are valid only when externally bypassed using a suitable contactor.

AC53b 4.5-30:330

40°C <1000 metres

22 A

44 A

55 A

AC53b 4.5-30:570

40°C <1000 metres

464 A

683 A

868 A

992 A

1606 A

1671 A

2030 A

414 A

490 A

658 A

774 A

857 A

997 A

264 A

395 A

70 A

87 A

117 A

136 A

146 A

200 A

223 A

264 A

345 A www.leroy-somer.com

3 9

Table 5-6 Digistart D3 current ratings - in-line connection, non-bypassed operation

Model

D3-1x-0255-N

D3-1x-0360-N

D3-1x-0430-N

D3-1x-0650-N

D3-1x-0790-N

D3-1x-0930-N

D3-16-1200-N

D3-16-1410-N

D3-16-1600-N

AC53a 3-10:50-6

40°C <1000 metres

255 A

360 A

430 A

650 A

790 A

930 A

1200 A

1410 A

1600 A

AC53a 3.5-15:50-6

40°C <1000 metres

222 A

351 A

413 A

629 A

790 A

930 A

1200 A

1355 A

1600 A

AC53a 4-20:50-6

40°C <1000 metres

195 A

303 A

355 A

532 A

694 A

800 A

1135 A

1187 A

1433 A

AC53a 4.5-30:50-6

40°C <1000 metres

171 A

259 A

301 A

437 A

567 A

644 A

983 A

1023 A

1227 A

Table 5-7 Digistart D3 current ratings - inside delta connection, non-bypassed operation

Model

D3-1x-0255-N

D3-1x-0360-N

D3-1x-0430-N

D3-1x-0650-N

D3-1x-0790-N

D3-1x-0930-N

D3-16-1200-N

D3-16-1410-N

D3-16-1600-N

AC53a 3-10:50-6

40°C <1000 metres

382 A

540 A

645 A

975 A

1185 A

1395 A

1800 A

2115 A

2400 A

AC53a 3.5-15:50-6

40°C <1000 metres

334 A

527 A

620 A

943 A

1185 A

1395 A

1800 A

2033 A

2400 A

AC53a 4-20:50-6

40°C <1000 metres

293 A

455 A

533 A

798 A

1041 A

1200 A

1702 A

1780 A

2149 A

AC53a 4.5-30:50-6

40°C <1000 metres

257 A

388 A

451 A

656 A

850 A

966 A

1474 A

1535 A

1840 A

4 0 www.leroy-somer.com

5.4.2 Selection example

► application: centrifugal pump

► full load current: 213 A

► starts and stops: required to start and stop twice daily (evenly through the day)

► other features required: water hammer control is required

The best soft stop method to control water hammer is Adaptive Control.

Typical start current for a centrifugal pump is 350%.

For 350% operation, the soft starter is rated AC53b 3.5-15:585 in bypass mode.

The smallest model which is rated >213A is D3-1x-0255-B for in-line connection or D3-1x-

0170-B for 6 wire connection.

However, with the low start frequency, it may be worth checking the sizing with the Digistart

Size software tool to see if a lower rated soft starter could be used.

Factors that may affect the sizing are:

► environmental conditions (altitude or ambient temperature)

► the installation bypassed or non-bypassed,

► the connection in-line or inside delta.

www.leroy-somer.com

4 1

4 2 www.leroy-somer.com

www.leroy-somer.com

4 3

MOTEURS LEROY-SOMER 16915 ANGOULÊME CEDEX 9 - FRANCE

338 567 258 RCS ANGOULÊME

Simplified Joint Stock Company with capital of 65,800,512 €

www.leroy-somer.com

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