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

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Discussion Overview

The discussion revolves around the maximum line current for electric vehicle chargers in a three-phase installation. Participants explore the implications of adding multiple chargers to a system, the nature of the loads (single-phase vs. three-phase), and the challenges of managing unbalanced loads in electrical circuits.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant describes a setup with three chargers operating at 32 amps each, raising questions about the current increase to 84 amps when a fourth charger is added.
  • Another participant clarifies that the system consists of three single-phase loads on a three-phase line, suggesting that adding a fourth charger causes two chargers to share the same phase, potentially leading to unbalanced loads.
  • Concerns are raised about the implications of creating an unbalanced three-phase system, which complicates measurement and analysis.
  • Some participants suggest using trigonometry or vector addition to analyze the current distribution, while others express confusion about the nature of the loads and the circuit design.
  • There is a discussion about the sizing of breakers in the distribution panel and whether the current exceeds recommended limits, with differing opinions on local regulations affecting these standards.
  • A participant mentions that they found a simpler solution to the problem, although the specifics of this solution are not detailed.

Areas of Agreement / Disagreement

Participants express varying levels of understanding and agreement regarding the nature of the loads and the implications of unbalanced systems. There is no consensus on the best approach to analyze the current distribution or the appropriateness of the circuit design.

Contextual Notes

Participants highlight the complexity of analyzing unbalanced three-phase systems and the importance of understanding local regulations regarding breaker sizing. Some assumptions about the nature of the loads and the circuit configuration remain unresolved.

  • #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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