1600 kW service, 3400 Amp conductors;

[electrofelon]

Back to the OP, the NG turbine is the correct method. The demand charges with Pacific Power are $15.50 per kW. That’s $28,000 per month in demand charges for ONE truck charger. The lease and gas costs of the oil rig turbine are about half of that.

True, demand charges can be very expensive. However, that is a very high demand charge and in many places it is lower. For example utilities in Washington state are about a third of that. Also many have no or a very low demand charge off peak. Finally, many utilities are starting to offer lower demand charges for EV charging based on the load Factor,

 

[electrofelon]

Are there CNG trucks available? I haven't heard much about that in the trucking industry.

 

[herding_cats]

Not a whole lot of CNG trucks out there but it will come. NG prices are tanking and the charging costs using natural gas (fuel only) are around .03 cents per mile. That’s how efficient gas turbines are.

The level 3 50kW charger we designed can charge a Tesla Model X fully in about an hour, at around .04 cents per mile NG cost.

Across all states (except Hawaii), natural gas costs are far lower than electrical costs. New Mexico has the cheapest natural gas at $2 per 1000 cubic foot. I’m in Missouri right now and it’s about $32 per 1000 cubic foot.

 

[winnie]

What is the expected utilization? Do they expect trucks to be charging at full rate 24x7, or do they want rapid charging capacity for 1 truck per day?

If the utilization is low, then the battery Tesla is suggesting might make a bunch of sense. Essentially it trickle charges at low power or at off peak times, and then sells power at high rate (and presumably a profit).

A single cycle gas turbine has about half the efficiency of a large central combined cycle plant.Smaller turbines are less efficient than large. Gas turbines are also very dirty when ramping. So I don't think a small gas turbine can really be equated to grid power produced by a natural gas power plant.

When you suggested 8 #500 per phase for 3400A, what sort of individual conductor ampacity and derating were you calculating? I don't see how you were getting 3400A.

Jon

 

[herding_cats]

The Tesla semi truck rectifier is rated for 1600 kW.

1600 x 1000 = 1,600,000 watts

Divided by 480 Vac

3,333 amps.

 

[herding_cats]

Without derating etc. Not much voltage drop. Short distance.

 

[herding_cats]

They want rapid charge at truck stops. 1600 kW charges the truck in 30 min.

 

[herding_cats]

Also the “gigawatt” battery from Tesla is $500k each.

 

[electrofelon]

They want rapid charge at truck stops. 1600 kW charges the truck in 30 min.

Another thought on the demand charges:. That demand charge may be insignificant if it is spread across a large number of charges. For example, just making WAG at 45 min cycles, 20 hours per day, that is 800 charges per month or only $35 per charge. Not sure how realistic that capacity factor is but seems very reasonable given some time if these things proliferate more.

 

[LarryFine]

The Tesla semi truck rectifier is rated for 1600 kW.

1600 x 1000 = 1,600,000 watts

Divided by 480 Vac

3,333 amps.

I think you omitted a 1.73 somewhere.

 

[herding_cats]

The demand charge is the issue here with grid connection. If you pull that kind of demand, even just 1 time, you are stuck with the demand charge for the next 11 months. We’re talking about 1 charger here. So because of the low volume of trucks, it’s impossibly expensive to charge a low volume of trucks.

 

[herding_cats]

I think you omitted a 1.73 somewhere.

I’m not talking about motor loads here. Teslas data sheet states the mega charger for the semi truck is rated at 480vac, 1600 kw.

 

[electrofelon]

The Tesla semi truck rectifier is rated for 1600 kW.

1600 x 1000 = 1,600,000 watts

Divided by 480 Vac

3,333 amps.

The only way you could make 8 500's work is by doing all three:
1. Using a 100% breaker
2. Using the conductors at their 90° ampacity which would involve transitioning to 75° ampacity at some point before the breaker.
3. No derating so no more than 3 isophase per pipe or regular divided sets with one set per pipe

This is somewhat basic stuff, do you not have a lot of experience with electrical construction? Is this something you would have an electrical contractor install?

 

[kwired]

Please explain how wind turbines stay in phase also.

The generator is a wound rotor machine, with one set of coils connected to grid that provides excitation for the other set, kind of hard to not be in phase with the grid with this method and is no different than some motor with high inertia load at a point when the load is running faster than the normal run speed. Excess energy involved at that point flows to the grid, a wind turbine just happens to have that excess energy being rather constantly supplied via the wind,

 

[herding_cats]

The only way you could make 8 500's work is by doing all three:
1. Using a 100% breaker
2. Using the conductors at their 90° ampacity which would involve transitioning to 75° ampacity at some point before the breaker.
3. No derating so no more than 3 isophase per pipe or regular divided sets with one set per pipe

This is somewhat basic stuff, do you not have a lot of experience with electrical construction? Is this something you would have an electrical contractor install?

That’s my question about single wire transformer rules. Because the pvc tubing is non conductive, you could put all of phase A, split between two 4” runs. I think 8 is not enough based on conduit fill. A response above sizes it in a response.

 

[kwired]

The Tesla semi truck rectifier is rated for 1600 kW.

1600 x 1000 = 1,600,000 watts

Divided by 480 Vac

3,333 amps.

That would be single phase amps, if you deriving this from three phase then there is that 1.73 factor involved as mentioned and 1600kW three phase @ 480 volts would be 1924 amps, split across all three lines.

 

[electrofelon]

That’s my question about single wire transformer rules. Because the pvc tubing is non conductive, you could put all of phase A, split between two 4” runs. I think 8 is not enough based on conduit fill. A response above sizes it in a response.

You can do ISO phase, but you are subject to derating which may kill it.

Due to the quick charging time, I take back the comment on it being a continuous load.

 

[herding_cats]

The data sheet said 1600 kw.

 

[electrofelon]

That would be single phase amps

How do you know that? I assume it is a three phase bridge rectifier.

 

[herding_cats]

Tesla has it in mind that the Cyber truck would use the semi truck charger also.

BTW I don’t work for Tesla or contracted by them. I’m working for a chain of truck stops that have 900 locations that are on the radar for Tesla charging stations for the semi truck.