Auxillary Contractor

The terms would be "auxiliary" and "contactor"; distinctions are not absolutely precise, but at least roughly, a "main" or "power" contactor would switch a large load such a a motor or heater, whereas an "auxiliary" contactor would switch a small load such as the coil of "main" or "power" contactor. An auxiliary contactor may also be called a "relay."

First justify, whether it is contactor or contractor?

It's not auxillary contractor or auxiliary contactor but auxiliary contacts. They are supporting contacts. Usually of a lesser amperage rating then the primary contacts which switch the load. They are for control circuit switching.

Then again any contactor could be called an auxiliary contactor by an OEM if in the curcuit design it is being used to support another contactor in switching a load. Usually done when control circuit current excedes the ratings of most relays.

Contactor vs "contractor" issue; most likely the OP was posting from an iPad or iPhone, which does not recognize the word "contactor" and automatically changes it. In order to make it come out right, you have to stop typing and tell it to ignore the autocorrect BEFORE you hit the first key of the following word or period. Its a pain in the rear but unfortunately Apple did not see fit to provide their Safari browser with the ability to add uncommon words to their dictionary. Drives me nuts. So please ease off on the condemnations, it's hard to avoid even if you are aware of it.

Get the spellings right as AP#1 has said. To add to what AP#1 has said, the aux. contactors usually switch on highly inductive contactor coils, so they have to pass a test for AC15 utilisation category as per IEC 60947-5. The DC duty is even more severe (100ms time constant!!!). So the aux contactors are sometimes designed for low bounce...here is an example...the bifurcated contact practically eliminates bounce.

There are some special aux. contactors which are designed for PLC interfacing where a bounce is not acceptable. There are some which have gold-plated contacts for 'dry circuit' continuity....

Sometimes an economizer circuit is also installed to reduce the power required to keep a contactor closed; an auxiliary contact reduces coil current after the contactor closes. A somewhat greater amount of power is required to initially close a contactor than is required to keep it closed. Such a circuit can save a substantial amount of power and allow the energized coil to stay cooler. Economizer circuits are nearly always applied on direct-current contactor coils and on large alternating current contactor coils. I would also recommend the bifurcated type...

Often when describing simple circuits for contactors, they refer to the aux contacts which latches the start circuit. It is, as described by others, an extra set of contacts that switch with the contactor.

The auxiliary contractor is usually the normal contractor's brother in law.

i see that there is some small confusion in the minds of some posters regarding auxiliary contacts and auxiliary contactors.

Both exist. Power contactors which switch on motors and other loads have usually 3 or 4 main contacts, and several auxiliary contacts depending on their design, space available, and application. These will be Normally open (for signalling and coil-holding duty), Normally closed (mainly for interlocking duty), Late-break NC (for economy resistor cutout duty), momentary NO (for capacitor switching duty) and so on.

There are also stand alone Auxiliary contactors (more correctly called 'Contactor Relays') which are nothing but small contactors used for switching mainly coils of big power contactors, whose inrush currents cannot be handled by pushbuttons or PLCs.

The terminals are numbered differently from power contactors....

This is a 4-pole Contactor relay with 4 NO contacts, rated 6A 415V AC15. The same basic product, with different markings, serves as a power contactor of 9A 415V AC3....

If it is "contractor", auxiliary contractor may be a sub-contractor doing any of the plumbing,electrical,AC,telephone,fire,music,CCTV etc to the main(normal)contractor.