Advantages of Soft Start Motor Control

2 2 ©  2011 Eaton Corporation. All rights reserved.

Advantages of Soft Start Motor Control


 This webinar will be available afterwards at designworldonline.com & email

 Q&A at the end of the presentation

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Before We Start


Moderator

Miles Budimir Senior Editor Design World

Design World

Presenter

Ram Tenneti Product Manager

Eaton Design World

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©  2011 Eaton Corporation. All rights reserved.

Advantages of Soft Start Motor Control

Hosted by Ram Tenneti Product Manager, Eaton Corporation


Agenda •  What is a soft starter?

•  Reduced voltage starting mechanisms

•  Inner workings of a soft starter

•  Soft starters for pumping applications

•  Soft starters in severe duty applications •  The value of soft starters •  Specification for various application

requirements


What is a soft starter?

•  A soft starter is a solid-state device used with AC electric motors to ramp up the voltage and torque on the motor during startup

•  This ramp up reduces mechanical stress on the motor and shaft, as well as the electro-dynamic stresses on the attached power cables and electrical distribution network

•  The bottom line: soft starters extend the lifespan of your system and reduce maintenance costs


Traditional reduced voltage starter types

•  Auto transformer •  Part winding •  Wye-Delta


Auto transformer starter

•  On start-up, line voltages are directed through transformers, which reduce the voltage

•  After an adjustable time, the transformers are removed from the circuit

•  Allow for simple closed transition from start to run

•  Minimal reduction in starting torque


Part winding starter

•  Constructed of two separate parallel stator windings per phase

•  One winding set energized on start, all windings energized during run

•  Time delay relay closes the additional run windings

•  Start windings draw 65% to 85% of the motor locked rotor current

•  Each winding set carries 50% of load during run


Wye-Delta starter configuration


Wye-Delta starter connected in Wye

•  Wye connection for START •  Typically use in applications

with high inertia and long acceleration periods (large centrifugal pumps, fans)

•  All stator windings are used during start-up

•  Less current draw at start-up


Wye-Delta starter connected in Delta

•  Delta Connection for RUN •  Close transition when

transferring between Wye and Delta requires inline resistors during transition (direct closed transitioning will cause a high inrush)

•  Open transition is most common

•  Full current draw


What is a soft starter, again?

•  Soft starter is a solid state device used with AC electric motors to ramp up the voltage and torque on the motor during startup

•  This ramp up reduces mechanical stress on the motor and shaft, as well as the electro-dynamic stresses on the attached power cables and electrical distribution network, thus extending the lifespan of the system


Solid-state starters

•  Electronically reduce the voltage output to the motor •  Typically silicone controlled rectifiers (SCR) are

used to reduce the voltage

•  Allows for greater control flexibility


Soft starter schematic diagram


Voltage ramp soft start

•  Smooth transition from initial voltage to full voltage


Inrush current comparison (300HP)


Why upgrade to soft starters?

•  Soft starter lowers inrush current compared to across-the-line and WYE-DELTA starting methods

•  Reduces stress on components (belts, chains, conveyors)

•  Reduces long-term maintenance costs •  Increases system uptime •  In pump applications, reduces water hammer effect by

utilizing pump control algorithm •  Reduces heat build up in enclosure because of

internal by-pass •  Reduces peak inrush current resulting in minimizing

penalty from the utility companies


Pump application challenges

•  High in-rush currents •  Squirling and snapping belts

•  Water-hammer


Understanding water hammer effect

•  Pressure surge caused by abrupt changes in the rate of flow because of pump starts and stops, opening/closing of valves or water column separation and closure

•  The abrupt changes can cause all or part of the flowing water column to undergo a momentum change

•  This change in momentum causes a shock wave that damages the system


Starting flow characteristics


Stopping flow characteristics


Soft starters for pump applications

•  Eliminates water hammer and check valve slam in hydraulic systems

•  Extended stopping time •  S-shaped torque curve to ramp up and ramp down the

flow


See the difference, watch the video

•  Eaton developed a short, 30-second video clip that shows the advantage of a soft starter in a pumping application


Heavy duty applications – reduced voltage soft start

•  RVSS used to improve Wye/Delta Start Characteristics •  Centrifuge:

•  10 minutes or more with Wye/Delta systems. •  4 - 5 minutes with RVSS. •  RVSS more tolerant of starts attempted with remaining process

in the centrifuge (Additional mass = longer acceleration time). •  RVSS provides full motor protection during start-run operations. •  Peak current ≈ 3.5 FLA, no spikes during contactor movement as

with Wye-Delta systems. •  Aggregate/Conveyor – Kick Start

•  Kick start to overcome friction •  Switch over to soft starter mode after couple of seconds


Success stories

•  Location: Pit mine •  Issue: Constant waterhammer effect -

experienced check valve slam as soon as the pump turned off

•  Challenge: A 285 HP pump discharging to very long piping system

•  Solution: Special softstarter with pump algorithm to reduce waterhammer effect was installed

•  Results: •  Reduced downtime •  Extended pump and asset life


Protection features in soft starters

•  Phase sequence •  Phase rev fault •  Motor rated volt •  Low volt trip •  Low volt level •  Low volt trip Dly •  Hi volt trip •  Hi volt level •  Hi volt trip Dly •  Jam fault •  Stall fault •  Temp sense fault

•  V imbal trip Dly •  V imbal trip Lev •  Phase loss fault •  Phase loss % trip •  Phase loss trip Dly •  Low I trip % FLA •  Phase Imb fault •  I Imbal trip lev •  I Imbal trip Dly •  SCR short fault •  Ground Fault


Full voltage retrofits

•  Soft starters typically fit in any MCC/enclosure installation you have today •  Box replacement not needed •  Built-in shorting (bypass) contactor minimizes

wiring •  Reuse all the same components you have today •  Quick installation saves electrician’s time and

down time


Soft starter solutions for various applications

Low Voltage Soft Starters Up to 1000Amps Up to 690 volts

Up to 800HP

DS7 DS6

S611

S811

S801

Up to 25 HP 0 to 480 V 1Q 2011

Up to 350 HP 0 to 600 V

Up to 150 HP 0 to 480 V

30 - 800 HP 0 to 690 V

30 - 800 HP 0 to 690 V


Soft starters for industrial applications Key considerations   Smaller in Size   Built-in run bypass contactor   Built-in overload protection   Adjustable ramp times   Adjustable kick start control   Physically fits in place of most

NEMA and IEC starters   Digital Interface   Pump control   Communication Capability

Product Range  Amps: 37 – 1000A  Voltage: Up to 690V  Power: 25 – 800HP


Soft starters for commercial applications Key considerations   Integrated bypass   Integrated electronic overload

protection   120V control  Power monitoring   Intuitive user interface  Serviceability (control board,

contactors)  Pump control option  ModBus Native  Plug and Play adapters for Profibus/

Devicenet/Ethernet IP  Available in NEMA 1/12/3R/4/4X

enclosures

Product Range  Current: 52 to 414A  Voltage: Up to 600V  Power: 40 to 350HP


Key soft start specifications

•  Compact size •  Integrated by-pass contactor •  Electronic overload protection •  Increased capacity of product when used in

inside the delta mode •  Feature-rich products with extensive

monitoring and protective features •  Pump algorithm to minimize/eliminate water

hammer effect


For more information

•  Multiple tools are available on Eaton’s website including application notes, podcasts, FAQs, quick start guide, manuals, catalogs etc. •  Visit Eaton’s soft starter

product page at: www.eaton.com/softstarters


Questions?

Design World Miles Budimir Email: [email protected] Phone: 440.234.4531 Twitter: @DW_Motion

Eaton Corp. Ram Tenneti Email: [email protected] Phone: 734.730.9513


Thank You  This webinar will be available at

designworldonline.com & email

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Date post:	24-May-2015
Category:	Technology
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Advantages of Soft Start Motor Control

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