Vacuum Contactor Coil 1

[charz]

The attached picture is control circuit of a solenoid latching vacuum contactor. It has an electronic unit to control the coils.

1) What is the purpose of this electronic unit?
2) Why the 52b contact is connected to the coils as I understand it is solenoid latching coil. Once the power goes OFF, the coil would be deenergized.
3) Why there are two coils in parallel? Is one coil not enough?

 

[GroovyGuy]

The 52b contact is required to de-energize the economizer coil (ie Coil-1) once the contactor has pulled itself in. The economizer coil is provided to supply additional closing power to the contactor. Once the contactor is puled in, the economizer coil is no longer required (ie Coil-2 will be able to provide sufficient holding power).

"I have not failed. I've just found 10,000 ways that won't work." Thomas Alva Edison (1847-1931)