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Anonymous Poster #1

Surge Protective Devices for EV Charging Stations, DC Loads

06/04/2021 2:15 AM

Hi all,

I work for a company for installing EV Fast chargers (internship)

Current scenario - we are planning to install 100kW EV chargers in a gas Station / Petrol Bunks / CNG Stations in India.

We are tapping 100kW supply from a Utility Transformer.

The transformer is at distance of 100meters from the location.

It has Lightning arrestors on the top of the pole.

From the transformer it comes to a utility metering Panel which is controlled by the utility.

From there it goes to a Main Station Panel.

From the Station Panel to goes to the Charger Distribution panel in which AC to DC conversion happens- 100kW.

From the charger Distribution panel it goes to the individual charging guns of 15kW DC.

Lightning Risk assessment done and it was deduced a SPD would be needed. (not done by me).

The station panel is located at 20 meters from the charger panel.

The charging gun is location at distance of 15m from the charger panel.

Now the Questions:

Type -1 SPD considered for the station Panel, is this okay?

Type-2 SPD considered in the Charger Panel because of the distance between charger panel and the Station panel. is this okay?

Type-3 SPD not considered at the Charging gun even though it is 15 meters away from the Charger Panel. the reason being, the charging gun is DC and is Electrically separated from the charger Panel by means of Rectifiers. Is this okay to not provide a SPD for the Guns? if not okay, any logical explanation would be helpful

Any thoughts on this is appreciated.

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#1

Re: Surge Protective Devices for EV Charging Stations, DC Loads

06/04/2021 1:10 PM

In my opinion, I would not consider rectifiers as electrical isolation.

Follow the electrons.

If those electrons can travel from your source to your 'guns', then it is not isolated.

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#2

Re: Surge Protective Devices for EV Charging Stations, DC Loads

06/04/2021 1:11 PM

My understanding of surge protectors is that they are to protect the equipment, and I might add that they are generally only good for a one time shot, additionally they are not 100% effective...this means they need to be checked and tested and possibly replaced on a regular basis...So for me this is a judgement call, is this area prone to lightning, will we be committed to proper maintenance and so on....so a risk assessment vs investment required, should answer the question...

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#3
In reply to #2

Re: Surge Protective Devices for EV Charging Stations, DC Loads

06/16/2021 1:20 PM

But it's only matter of time we see somewhere what a beefy unclamped ligtning surge would do to a large charging Li battery. Not talking for this OP system of course. I think it should be pretty spectacular. I get nightmares with... ElectroCavaliers not starting. (LOL). S.M.

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#4
In reply to #3

Re: Surge Protective Devices for EV Charging Stations, DC Loads

06/16/2021 3:00 PM
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