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| What kind of variable load does an EV car present to the EVSE? |
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| coppice:
--- Quote from: fcb on January 07, 2020, 01:44:36 pm ---If you are metering energy use inorder to charge £$ for the service, you are about to enter a whole world of s***. --- End quote --- Not really. WELMEC, OIML, and ANSI set the standards for most legal metrology around the globe, including charging for electrical energy. The specs are straightforward, and not difficult to comply with. They include the harmonic content you need to deal with, although many utilities require the meters they buy to go beyond those requirements. There are a number of electrical energy measurement chips designed specifically to meet these standards. |
| fcb:
There are no half-measures when it comes to metering for revenue purposes. It is either fully tested and compliant or not. Building a metering system is not hard, paying for the testing is. Just try getting a price out of test house. |
| ejeffrey:
--- Quote from: coppice on January 07, 2020, 10:58:35 pm --- --- Quote from: fcb on January 07, 2020, 01:44:36 pm ---If you are metering energy use inorder to charge £$ for the service, you are about to enter a whole world of s***. --- End quote --- Not really. WELMEC, OIML, and ANSI set the standards for most legal metrology around the globe, including charging for electrical energy. The specs are straightforward, and not difficult to comply with. They include the harmonic content you need to deal with, although many utilities require the meters they buy to go beyond those requirements. There are a number of electrical energy measurement chips designed specifically to meet these standards. --- End quote --- Not only what fcb said about testing and verification, but if you are actually deploying these (rather than just manufacturing them) you have to worry about the laws that govern utilities. As usual, the US has taken many approaches here. So for instance in some states only utility companies can sell electricity. Therefore public EV chargers cannot charge metered power unless they are owned by a utility company. On the other hand California recently ruled that chargers are de-facto selling electricity and therefore it must be metered -- charging per minute will no longer be allowed. At the same time California also ruled that the charger must have an easily visible real-time readout of the rate and total kWhr (basically like a gas pump) and that relying on the screen in a customers vehicle or cell phone is not sufficient. |
| coppice:
--- Quote from: ejeffrey on January 08, 2020, 12:40:02 am --- --- Quote from: coppice on January 07, 2020, 10:58:35 pm --- --- Quote from: fcb on January 07, 2020, 01:44:36 pm ---If you are metering energy use inorder to charge £$ for the service, you are about to enter a whole world of s***. --- End quote --- Not really. WELMEC, OIML, and ANSI set the standards for most legal metrology around the globe, including charging for electrical energy. The specs are straightforward, and not difficult to comply with. They include the harmonic content you need to deal with, although many utilities require the meters they buy to go beyond those requirements. There are a number of electrical energy measurement chips designed specifically to meet these standards. --- End quote --- Not only what fcb said about testing and verification, but if you are actually deploying these (rather than just manufacturing them) you have to worry about the laws that govern utilities. As usual, the US has taken many approaches here. So for instance in some states only utility companies can sell electricity. Therefore public EV chargers cannot charge metered power unless they are owned by a utility company. On the other hand California recently ruled that chargers are de-facto selling electricity and therefore it must be metered -- charging per minute will no longer be allowed. At the same time California also ruled that the charger must have an easily visible real-time readout of the rate and total kWhr (basically like a gas pump) and that relying on the screen in a customers vehicle or cell phone is not sufficient. --- End quote --- The testing for a meter isn't really that much worse than most other products. Testing anything gets expensive when you add up EMI/EMC testing. safety testing, and any functionality tests. Testing a meter is a lot cheaper than testing, say, a radio device. I thought the original poster was trying to develop a product. If they are trying to deploy a service things may get a lot more complex. In some places landlords can sub-meter their tenants. The regulations for that could well be applicable to metering charging stations, but these things are going to vary with time and location. If California is banning timed charges, is that going to impact the charging networks which charge large per minute penalties for not freeing up the charging station soon after the charging operation is complete? |
| rstofer:
If you just want to meter the circuit serving a charger, buy a revenue meter. They are already approved for the application, their tolerances are known and they will likely match what the local utility is using. This is just the first one I came across https://www.gordonelectricsupply.com/p/Milbank-Cl200-D-200A-Watt-Hour-Meter/5952665 Applications will vary. |
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