Electronic – Four-contact push-button switch; what’s the pictured switch called

I have single phase submersible pump, around 400 foot underground in a Bore-well and its controlled by the controller shown below.

The green button is a push-button switch which if pushed and held for 5 seconds, starts the pump.

I would like to know what the switch is called, it has 4 contacts shown below (top right).

Here is the complete album of the controller:

http://imgur.com/a/U01qs

I am planning to replicate the switch function using Arduino and high load relay.

The button reads MAX 600V.