Auto-Transformer Starters

i would recommend the closed-transition (Korndorfer) Auto-transformer starter. i haven't seen a reactor starter in reality, only in text books. Here is a good paper on the ATS : ABB ATS.pdf

Have had a trawl around various site and so far not come up with a single advantage to a reactor starter. As kvsridhar says go with the Korndorffer starter.

Most sites seem to regard the reactor starter as a rip off.

The only advantages to reactor starters are lower cost / size and less complexity (one fewer contactor). The disadvantage is that you buy the reactor and if the torque it creates is insufficient, you are stuck with it, nothing is adjustable except the transition time. Whereas with an autotransformer you have 3 taps to select from, giving you some amount of flexibility in the field to adjust to conditions (but less so than Solid State). So some OEM machinery mfrs will still favor reactor starters because they can engineer the reactor specs to make absolutely sure it will start their machine, so they can use the cheapest option. But that is basically impractical for people using them in the field. That's why you rarely see reactor type starters sold out of catalogs. The only place I still see reactor type starters used in Low Voltage applications is Fire Pumps, because they are always engineered solutions.

Here is a paper on the subject, there is a nice little comparison chart at the very end.

They are still offered quite often in Medium Voltage controllers however, because the theory is that an MV application will likely be an engineered solution anyway.

The reactor starting is expensive for the starting of small motors and hence not used normally in industry. For starting high voltage high current motors it is economical and advantageous . It helps for smooth starting. Cummins power generation manual gives a good technical comparison on the subject.

thank u all

i have realized the difference well .

can u suggest me any website to guide me in designing of a series reactor .

thanks

what i mean is a simple calculations - to select the wire size - the dimension of the core the number of turns for a specific motor .