What is the maximum line current for an electric vehicle charger?

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SUMMARY

The maximum line current for electric vehicle chargers in a three-phase installation at 220 V and 7.04 kW is 32 amps per charger, totaling 96 amps for three chargers. However, adding a fourth charger (Q4) results in a current of 84 amps due to the unbalanced load created when two chargers operate on the same phase pair. This scenario complicates the analysis of the system, requiring an understanding of symmetrical components and the implications of delta versus wye connections. Proper sizing of circuit breakers is essential to prevent nuisance tripping and ensure safety in the installation.

PREREQUISITES
  • Understanding of three-phase electrical systems
  • Knowledge of symmetrical components in unbalanced systems
  • Familiarity with circuit breaker sizing and protection methods
  • Basic principles of electrical load calculations
NEXT STEPS
  • Research "symmetrical components in electrical engineering" for deeper insights into unbalanced systems
  • Learn about "circuit breaker sizing standards" specific to your region
  • Explore "three-phase load calculations" to understand current distribution
  • Investigate "delta vs. wye connections" and their impact on electrical systems
USEFUL FOR

Electrical engineers, electrical project managers, and professionals involved in the design and installation of electric vehicle charging systems will benefit from this discussion.

  • #31
Skinbleu said:
We can consider the charger as a purely resistive load, since the power factor is 1.
That is quite an accomplishment! So you are saying that the switching power supplies in your chargers have very effective (and complicated and expensive) Power Factor Correction input circuitry?
 
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  • #32
Skinbleu said:
I agree that the current must be sized 125% of full load current.
That comment clearly contradicts:

Skinbleu said:
To size breakers:

Ib<= In <= Iz

Where:
Ib - circuit current
In - breaker current
Iz - conductor current
 
  • #33
Averagesupernova said:
That comment clearly contradicts:
I said I agree, because I think it's the right thing to do. But the norm here is different, this 25% margin is not considered
 
  • #34
berkeman said:
That is quite an accomplishment! So you are saying that the switching power supplies in your chargers have very effective (and complicated and expensive) Power Factor Correction input circuitry?
The chargers only rectify the alternating current into direct current to recharge the vehicle's battery. In this process we don't have inductive or capacitive loads.
 
  • #35
Skinbleu said:
The chargers only rectify the alternating current into direct current to recharge the vehicle's battery. In this process we don't have inductive or capacitive loads.
Doesn't matter. Your Power Factor is terrible with just a rectifier (and I don't understand how you use just a rectifier for the charger circuit anyway; that's weird).

Do you know what Power Factor means? Do you know what the voltage and current waveforms look like for a simple rectifier circuit? Why do recifiers have a poor Power Factor?
 
  • #36
berkeman said:
Doesn't matter. Your Power Factor is terrible with just a rectifier (and I don't understand how you use just a rectifier for the charger circuit anyway; that's weird).

Do you know what Power Factor means? Do you know what the voltage and current waveforms look like for a simple rectifier circuit? Why do recifiers have a poor Power Factor?
This more in-depth technical information only the charger manufacturer has, we buy the charger from a factory in Europe. I will show you some information that I have.
 

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  • #37
I don't see anything about Power Factor in the datasheet pages (maybe I missed it?), but it looks like it can run off of all 3 phases too. Wouldn't that be a more balanced way to run the multiple chargers?
 
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  • #38
After reading the data sheets you supplied, I note the following:
  1. Two different models are available: SIngle phase, and Three phase
  2. The Maximum Charging Power can be adjusted at installation time
  3. Overcurrent Protection can be 16A to 40A, probably depends on setting of Maximum Charging Power
  4. Maximum Line Current is 32A

Given 3 & 4 above, the Circuit Breaker should be 125% of Maximum Line Current.

Note also: The breaker short term withstand current should be 6 000A.
I do not know for sure but, that sounds like a heavier breaker than is usual in home or office use.


Cheers,
Tom
 

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