Introduction
Introduction To HFSR Reactor Soft Starter.
1) What is a Reactor Soft Starter?
Reactor Soft Starter is a device used to control or restrict the starting current of a 3Ø AC motor.
2) Why is Soft Starter required?
When a motor is started in Direct On Line (DOL) mode, usually its starting Current is 6 to 8 times its full load Current and the starting torque is far in excess of the load torque.
The sudden mechanical impact at start up on the load, followed by the rapid acceleration to full speed causes excessive wear & tear on:
- Belts and pulleys
- Gears and chains
- Couplings and bearings
- Cavitation in pumps, and more.
The electrical impact of large starting current can be severe enough to cause:
- Large voltage dips and damage to computers & other electronic equipment on the line.
- Supply voltage drops in case of weak supply and thus affect the entire operation or community.
- Pitting and burning of switching contacts due to high currents which are many times the motor full-load current.
- Increased line losses.
- Risk of exceeding sanctioned maximum demand.
These unwanted Mechanical & Electrical effects can result in substantial additional cost to the company due to:
- More frequent and unscheduled maintenance.
- Greater chance of unscheduled shutdowns – productivity loss
- Oversized mechanical and electrical components to cater for the power surge on start up.
- Short component life.
3) What are the advantages of Reactor Soft Starter?
Soft Starters save energy during starting by controlling the inrush current and provides a smooth and jerk-less start to eliminate the negative Mechanical and Electrical impact of a Direct On Line start.
Soft Starter also takes care of other failures such as –
- Phase loss
- Earth fault
- Phase imbalance etc.
- Over heating of motor due to frequent starting.
As a result, the life of the motor increases and also the maintenance of transmission parts and motor reduces.
The result is substantial financial benefits due to reduced maintenance, longer motor life, lower energy costs and reduced production down-time.
Current Vs. Time Graph for DOL and Soft Starter.
Methods
There are three basic methods for starting fixed speed 3 Ø AC motor
- Full Voltage or Direct On Line Starting [DOL]
- Reduced Voltage Starting [SOFT STARTER]
- Part Winding Starting [AUTOTRANSFORMER]
Soft Starter falls under the 2nd method.
It is a very simple and elegant device that reduces the motor’s Terminal Voltage at the time of starting to reduce starting current and to deliver starting torque that is sufficient to overcome the load torque.
Reduction in Starting Torque is proportional to the Square of the reduction in Terminal Voltage.
For example –
If the voltage is reduced to 50% of full voltage, the torque will be (.5) ² = .25, i.e. 25 % of
the full torque [while starting]
Hence, while designing a Soft Starter, the torque requirements must be the prime
factor on which other parameters should be taken into consideration.
There is no 'magic'. The relationship between the motor’s Terminal Voltage and Torque is governed by the laws of Physics and cannot be changed by human. Hence the torque-speed characteristics of the load and the motor are the primary factors that determine the design of a Soft Starter.
The design of the Series Reactor should be such that it will introduce impedance
in series with the motor winding, which will reduce the voltage at the motor terminals to the desired value.
The Series Reactor Starter is designed to introduce variable impedance in series with the motor windings which reduces the motor terminal voltage to the desired value for starting and then gradually increases it for a smooth and controlled start.
An important factor that should be considered while designing this series impedance
is that the impedance itself should not consume any energy; it should not generate heat, electrical and mechanical noise & vibrations.
Reactor Design
The Series Reactor can be designed by two methods.
- Coreless [ Air Core Reactors]
- Iron Core Reactors.
Over the years, a lot of research has been done on these two methods of core designing and time and again it
has been proven that Air core [core less] type Series Reactors are superior and are the right choice while designing the Series Reactor for Motor Starter.
General comparison between two methods.
| Parameter |
Coreless |
Iron Core |
Comments. |
| Copper |
High volume of copper is required to achieve desired impedance |
Less copper is required due to iron core. |
Some Manufactures prefer to use iron core in order to reduce the material cost. |
| Characteristics |
Perfectly linear |
Non linear |
A good design is always achieved with the help of Air Core Reactors. |
| Core Losses |
No Losses |
Iron Losses heating due to eddy currents & hysteresis losses |
Iron Core Reactor is much less efficient where as the Air Core Reactors are highly efficient |
| Weight and physical Dimensions |
Light weight,
But costly |
Bulky, heavy, Bigger in size
But economical. |
Various problems are linked with iron core Reactor, such as saturation of iron core, eddy currents and iron losses and heating. |
Harmonics |
Not present. Air Core Reactors are used as harmonics filters |
Present, due to saturation of iron core |
Iron core can prove to be dangerous for the other equipments on the same line |
Magnetic Flux is another important design parameter that affects the performance of a starter. Air Core Reactor coils are carefully placed in space to create a neutral point at the centre of the 3 reactors.
In Iron core Reactors, magnetic flux gets a path through the Iron core. This alternating flux causes eddy currents & hysteresis losses in the Iron core and and can cause core saturation when the core size is small. These losses get converted into the heating of the iron core and restrict the frequency of consecutive starts. Hence the ‘flux compensation‘ in the iron core Reactors has adverse effects for the motor starting application.
A carefully designed Iron Core, which has a much bigger size than that of Air Core Reactor, is always used for designing a transformer; hence iron core technology is meant for transformer design as it is best suited for this application.
We at Jayashree Electron, carefully design the Reactor coils placed 120 º in space.
The coils are vacuum impregnated and insulated with ‘H’ class insulation, with epoxy treatment for zero maintenance.
Typical arrangement of air core reactors, 120 º placement in space.
References
If we take a look at various famous Books for motor control, it is always seen that starting with a reduced voltage Soft Starter
is essentially an open loop process, where no feedback is required as all the parameters are predesigned
and calculated. As there is no feedback, it is obvious that there is no scope or NEED
for amplification of any parameter and also there is no need to complicate the simple process of series impedance.
If dynamic impedance control is to be provided, it would be done by providing an auxiliary winding/reactor which will generate magnetic flux
in the opposite direction or in the same direction of the main reactor to increase or reduce the effective series impedance in
real time of the soft starter.If the reactor is so designed, it has to be tap-less reactor with an
additional reactor control circuit along with power contactor which is same as that of bypass contactor with a current
control mechanism to change the flux of the control reactor in real-time.
If this method is used, a reactor can be designed with minimum information about the motor. It will not have any taps and it can be a
general solution for a range of motor sizes. However, it will be an extremely expensive solution with no real extra value delivered for the additional cost.
So a tapped reactor designed for a specific motor / load combination, which is adjustable on site, is always a smart & economical choice.
So whenever there are taps present to a reactor, it is essentially an open loop predesigned reactor for the specific motor.
Some of the reference Books are –
| 1) Electrical Control Systems in Industry – |
C.S. SISKIND (1963)
ISBN 07-0-577463 |
| 2) Alternating Current Machines – | M.G. Say (1936)
ISBN 0273 36197X |
| 3) Electric Motor Guide – | Edwin (1968) |
| 4) Handbook of Electric Power Calculations – | ISBN 007 136298 – 3 |
| And many more – | |
The scientific name of this method is Series Reactor Soft Starter.
1.0 Scope of IS Standards:
The motor soft starter design as per the IS 5553 [ part 3 ] working on the principle 'series Reactor for current limiting of 3 Phase motor '
This specification covers the requirement for LT/HT REACTOR soft starters from 415 V TO 11 KV. The product shall comply with the requirements of IS 13947 Part-4 for Low voltage switchgear and control gear.
Any material and component not specifically stated in this specification but necessary for trouble free smooth operation of the equipment and the accessories listed below in clause 2.0
2.0 OTHER RELEVANT STANDARDS:
Sl No. |
IS No. |
Specifications |
1 |
IS 12661 (Part-1):1998 |
Specifications For High Voltage Motor starters |
2 |
IS 5553 [ part 3 ] /IEC 289 |
Reactor Specifications – current Limiting reactors for 3 Ph motors |
3 |
IS 2705(Part 1,2 and 3):1992 |
Current transformers- Specifications(General Requirements, Measuring and Protective Current transformers) |
4 |
IS 3427:1997 |
AC METAL Enclosed Switchgear and Control gear for rated voltage above 1 KV and up to & including 52KV |
5 |
IS 13118 |
General Requirements for circuit breakers for voltage exceeding 1000 V AC |
6 |
IS 13947 part-5/Sec 1 |
Requirements for Control circuit devices and switching elements |
7 |
IS 12021(Part 0/Sec 0):1987 |
Specification for control transformers for switchgear and control gear for voltages not exceeding 1000 Volt ac |
8 |
IS 13974 |
AC Contactors not exceeding 1000 V AC |
9 |
IS 1901 |
Indicator Lamps |
10 |
IS 1766 |
Time Switch |
11 |
IS 2147 |
Degree of protection provided by Industrial enclosure |
12 |
IS 3043 |
Code of practice for earthling |
13 |
IS 13947(Part 1/Sec 0):1993
|
Low-voltage switchgear and control gear: Part 1 General rules (superseding |
14 |
IS Code of practice for electrical wiring |
LV Switchgear and control gear: Part 2 Circuit breakers (superseding IS 2516 & its parts) |
15 |
IS 13947(Part 3/Sec 0):1993
/ IEC 60947-3(1990) |
Low-voltage switchgear and control gear: Part 3 Switches, disconnectors, switch-disconnectors and fuse combination unit |
Beware of manufactures who misguide customers by selling the same product [Series Reactor - iron / air core]
with different fancy names and a fancy price tag.
The beauty of the Series Reactor Soft Starter is in the optimal design of the Reactor coil as per the motor and load requirement to make a perfect match.
Design Your Soft Starter
With Reactor coil, the current of a motor can be controlled up to an extent, where the Motor torque is slightly greater than the
load torque for the motor to accelerate. If one wishes to restrict the burden on the generator or line side,
a Capacitor Bank may prove to be useful to relax the momentary demand of the motor during starting. These capacitors can be later utilized
to control the power factor of the systems.
To design your Soft Starter, please enter the following parameters.
Enter as much possible data / information in the above blocks, so that we will be able to supply you with following information.
| 1) Motor starting current with Soft Starter |
| 2) Total starting time. |
| 3) Soft Starter curves superimposed on motor curves. |
| 4) Number of taps for various onsite settings. |
| 5) Capacitor Bank Value. |
| 6) Panel Dimensions. |
Our advance software can predict and plot the various cases and can make you visualize how your motor will perform with different load condition for different starting Ramp up time and current limits.
General Arrangement Scheme of Neutral Side Soft Starter.
Std. Specs
| Supply : 415V / 3300V / 6600V / 11000V AC |
| Control Voltage : 110V DC / 240V AC, 50 Hz Auxillary Supply |
| Duty Cycle : Maximum 4 Equi-spaced starts per hour. OR Maximum 2 cold starts & 2 hot start per hour |
| Method of cooling : Natural air cooled |
| Working Temperature : 55°C maximum |
| Altitude : Max 1000 meters from sea level |
| Space Heater : Powered on auxillary supply |
Enclosure : 2/3 mm sheet steel floor mounting cubicle with bottom / side cable entry in IP-32/41/55 grade of protection suitable for indoor installation.
Capacity:
LT Reactor type soft starters :- 100 /Month
MV Reactor type soft starters :- 75 /Month
HT Reactor type soft starters :- 60 /Month
Standard applications of this type of soft starters are:-
| Small / Large Capacity Pumps |
| Low / High Inertia Fans |
| Compressors- (Reciprocating, Screw, Rotary) |
| Crushers |
| Grinders |
| Conveyors |
| Pulp, Paper & Packing |
| Agitators |
| Press |
| Mixers |
| Download Catalog |
| Ask for More technical literature and information. |
| Enter your field of interest and comments and submit to us, we will come back to you ASAP ! |
Download Software Demo
Ask for:
For further detailed documentation and information about motor starting methods and Air Core
Reactor application / Soft Starter information,
please contact Mr. Mihir Dabke at
mihir@jayashree.co.in or call on +91 20 30681343.
Demo Curve plotted by the Jayashree Electron software for soft starter design.
Why Jayashree?
Why Buy JAYASHREE Soft Starters?
Today JAYASHREE is the oldest name in India known for Soft Starters.
The concept of 'Series Reactor Soft Starter' was introduced to the industry for the first time in the world by JAYASHREE in 1978 and the development of the Technology is traced back to 1974.
JAYASHREE'S philosophy has always been to develop a product that will meet the necessary National and International industrial standards, meet the customer requirements and to produce an everlasting product to ensure complete satisfaction and peace of mind for the user.
The success story of JAYASHREE Soft Starters goes back to 1978, when the first 6.6 KV. Reactor Soft starter (Air core Technology) was installed achieving current reduction of more than 50%.
Till date, since the last 30 years, this Soft Starter is running successfully without and trouble or maintenance,
JAYASHREE has technical collaboration with M/S.FAIRFORD ELECTRONICS, [U.K.] since 1990, for electronic Soft Starters, who has the patent for the electronic Soft Starter Technology.
Today JAYASHREE is the 'One Stop Solution' for all your Soft Starter and energy saving needs.
JAYASHREE is the only company to have 'Series Reactor' as well as 'Electronic' type Soft Starters designed and manufactured under one roof.
JAYASHREE not only provides the complete Soft Starter solution, but also has the expertise and facility to design and manufacture power factor controllers, capacitor panels, synchronization panels, slip ring motor constant current controllers, energy saving starters RS 485, Remote control, Motor protection relay, Vacuum circuit Breakers.
In short 'a one step solution for all your starter needs!'
Be comfortable with us!
When ever you deal with JAYASHREE, you will never experience an unwanted marketing bla bla. We at JAYASHREE know that your time is very important, and you are very important to us!
So no non sense! We are committed to deliver a genuine and state of art product.
Our focus is always to design and manufacture a standard and technically correct product. We never misguide the customer by making things sound complicated / complex and confusing!
We always deliver what we claim!
Ex.:- we call our Soft Starter as HFSR (Harmonics free series reactor) But, whenever we interact with our customer, we always refer to our product with its technical name (i.e. Series Reactor Soft Starter) and not HFSR
The true features of JAYASHREE!
- All the designs of Soft Starter are always, as per IS/IEC standards.
- All the designs and manufacturing process follow a strict systems based on ISO 9001:2008 [ Germanischer Lloyd certified]
- All the components and devices used in our product are also carefully selected as per IS standards [ See annexure I]
- All the panels are always CNC fabricated to meet the professional look, design and state of art quality.
- Complete transparency with Customers.
- Availability of complete technical data.
- Sharing of methodology, explaining all the design aspect of product.
- Availability of all the details of all the components used in the systems.
We at JAYASHREE do not just sell the product……… We share the trust, confidence and we build ever lasting relation!
We believe in sharing the knowledge and not just showing it!
- Truly professional approach and methodology for design function. Completely automated software controlled design giving full Information about all the motor starting parameters to customer.
- A full fledged testing lab for the entire range of Soft Starters.
- Individual monitoring and testing at every step of Soft Starter designing and manufacturing.
- Thousands of installations running successfully all over India and overseas.
- All the approvals and certificates are available.
So that’s why JAYASHREE!! Once you are dealing with Jayashree, just sit back and relax!!
The most reliable way to smooth start your motor …
is ….
Jayashree Soft starter!!
