High voltage contactor EMC circuit

Question

I am using a 12V relay to drive high voltage contactors. The contactor coil causes EMC when turned off. I am uncertain of which circuit I should use for reducing the EMC. Is there even any difference between option 1 and 2?

Secondly It was recommended that I should use a 24V zener diode. But I couldn't find any information on what current rating the zener diode and the normal diode should have. The operating current of the HV contactor coil is around 0.5A. Should the zener diode be able to handle the whole operating current? Is there a way to estimate it?

I had trouble finding a datasheet for the contactor it's name is AEV6505A from panasonic. So I based my info on a similar contactor I looked at the specs for the highest current contactor just to be safe.

EDIT! Would this zener diode work since it has a " Non Repetitive Surge Power Dissipation" of over 100W at 1ms. And the maximum wattage from the coil is only 0.5A*12V=6W?

EDIT 2! Thanks for all the answers!

^{simulate this circuit – Schematic created using CircuitLab}

Answer 1

High Voltage contactors need to switch as fast as mechanically possible to reducing the harmful effects of arc currents on the contact surfaces at extreme temperatures ~ 6000’K.

When a simple relay or inductor is clamped by a reverse diode, the same coil current travels thru the diode with the reverse voltage. When such clamping occurs the force on the coil persists and the decay time can be estimated by the L/R=T . Thus a low R conducting diode will force the relay to open slowly, exactly what you don’t want for a HV contactor.

Your figures A & B are identical because series elements are swappable.

However the addition of a Zener will dissipate more power in the diode, yet it will switch much faster. Because dI/dt=V/L the Zener voltage allows some drop in current due to the rise in voltage. Yet it is not very much voltage and power can be a problem for Zeners unless bulky.

Another solution is to allow much higher switching voltages by using an RC snubber to absorb the energy stored in the coil and increase the V=I*R transient across the switch within its allowable safe operating area (SOA). This gives the contactor or power relay the best possible solution for switching the contacts open and quenching the arc.

Then next possible solution to prevent damage is to use a large power snubber for flaming contactors to divert the arc energy to an external RC dummy load.

The specifics require you to define the actual VA being switched and inductive energy stored.