Purpose of Contactor in HPC500 Controller

[Kinematik]

Hi, I am working in an electrical scooter and therefore I purchased a GoldenMotor 10kW BLDC motor together with a controller VEC500.

I have already connected all the parts and it worked flawlessly first time in my tests.

However I also received a SAYOO MZJ-400A DC CONTACTOR in the delivery, and I am trying to understand the purpose of this 72Vdc contactor, so far I did not use it, because I really don´t understand why I need it.

Do I need really this contactor, or its purpose is only to provide extra security?
You can find the Sayoo contactor datasheet here: http://www.sayoon.com/uploadfile/PDF12/MZJ-400A_E_SAYOON.PDF

[Bikemad]

Hi Kinematik andto the forum.

A contactor is basically a heavy duty relay that is used for switching higher voltages and currents, and this basically minimises the possibility of burning out (or welding together) the contacts, as can often happen with low voltage/low current switches when they are overloaded.

The heavy duty contacts within the contactor will also ensure the circuit is completely disconnected when required as the contacts can withstand high current switching without becoming welded together by the arc that is formed when the switch contacts open and close.

If your existing battery switch is suitable for switching (and disconnecting) high currents (and high voltages) then you may not need to use a contactor.

But if you decide to install the contactor, just make sure that the voltage rating of the contactor's windings is suitable for the voltage being used to energise those windings. 

Alan