Abstract- Each industrial grade product must pass through a compliance certification process before hitting the market. The certification can be mandatory, recommended, or a ‘feather in the cap’ type of recognition, depending on the geographic regions where the product is manufactured and sold. Recently, with a surge in safety and cyber security awareness, the number of required certifications has increased, and compliance rules are becoming strict. Thus, the certification process for products has become more challenging for manufacturers. Additionally, the required certifications and processes are not centralized on a single platform, forcing manufacturers to spend significant time gathering information. The certification process can also be costly, and applying for the same certification multiple times may impact the overall project budget. These challenges motivated me to write this blog to provide concise yet essential information on standards and certifications for Electric Vehicle Supply Equipment (EVSE) products, helping manufacturers access key details quickly and in one place.
This blog covers the mandatory, recommended, and add-on standards/certifications for EVSE products and the process for each certification based on our extensive experience on EVSE products. So, let us get started.
UL 2594 [Standard Testing for EVSE]:
This standard focuses on user safety and covers multiple tests accordingly. This is a mandatory certification process in most countries because EVSE deals with high electric power that can harm living beings. This evaluation covers electrical safety, mechanical safety, Electromagnetic Interference (EMI), stress, over/under temperature, and radio frequency interference to confirm user safety.
Process:
After applying for this certification online, the manufacturer sends the product to Underwriters Laboratories (UL) certified locations where the experts perform different safety tests. Electrical safety evaluation includes grounding, insulation, and over voltage/current test. To verify mechanical safety, the testing team hits a hard object on the device to confirm the EVSE body is strong enough. A statically charged pen is used for the static charge immunity validation, especially when the EVSE is in charging state. To validate the Radio Frequency (RF) immunity, bombards radio signals with different frequencies on the EVSE while charging and measures the charger’s emitted signal power. The EVSE must be capable of charging and not generate any non-recoverable faults during and after applying the RF signals. There are a different emission thresholds for industrial and residential grade products, so the EVSE must comply as per its specification. The RF test can only be performed with special lab equipment and environment. The Validation team pulls the charger cable thousands of times to confirm stress immunity. The Certification labs keep updating the test processes and adding new tests, so consider the above information for reference only and refer to the latest specifications and test process shared by the certifying lab or body.
UL 991 [Tests for safety-related controls employing solid-state devices]:
This standard outlines tests designed to evaluate the effects of environmental stress on the product. The product must comply with all tests that are part of this standard including over/under voltage, power supply interruption, humidity, thermal cycling, vibration, jarring, ramp voltage, electrostatic discharge, and electromagnetic susceptibility. This is a mandatory standard that must be followed in nearly all regions.
Process:
For under-voltage and over-voltage conditions, the EVSE must work normally for an extended period at the rated limits of the product specification, ensuring that the temperature does not rise exponentially. In the thermal cyclic test, the temperature repeatedly varies between extremely low and extremely high values over a short period, as specified in product requirements. The EVSE must be capable of charging both during and after the test. During the dust test, dust circulates in the test chamber for 5–10 minutes while the EVSE is in charging mode. The EVSE must continue charging even after the test concludes. For the humidity test, the EVSE is placed inside a chamber where the humidity is gradually increased to an extreme level, approximately 90 percent of the normal operating range. In the vibration test, a sinusoidal vibration is applied to the product. After the test, the EVSE must remain capable of charging. As the test process changes periodically, please use the above information for reference and get the latest test process from the certifying lab or body.
UL 2231-1/ UL2231-2 [Standards for Personal Protection system]:
These standards apply to the control circuits used for charging, rather than the entire product, and are intended to ensure that the users are protected from electric shock during operation. UL 2231-1 verifies that the control circuits are following the ANSI/NFPA 70, Article 625, National Electric Code (NEC). UL 2231- 2 confirms that the EVSE has full proof ground and isolation monitoring, which detects the fault and reacts immediately. These are mandatory standards for the EVSE to comply with in almost all regions.
Process:
UL 991 tests like humidity, impact, vibration, and harmonics distortion are part of these standards but they also cover Charge Circuit Interrupting Device (CCID), ground monitoring, voltage surge, voltage dips, voltage variation immunity, magnetic field immunity, capacitor switching transient test, and general protection verification.
For CCID immediate and non-immediate tests, different levels of leakage current—ranging from 5mA to 60mA—must be applied to verify that the EVSE correctly detects the CCID fault and opens the relays within the defined time limits. I can cover how we performed some of the above-listed tests as part of the pre-certification process but as the test process changes, it is recommended to contact the UL for the latest test steps.
UL 1998 [Standard for Software in Programmable Components]:
This certification is more related to software and focuses on the EVSE contactors’ behavior in case of different faults and unexpected scenarios. This standard evaluates whether the EVSE software reliably detects all defined faults and promptly opens the contactors. Some buyers expect EVSE products to comply with this standard.
Process:
The manufacturer must apply online and share the necessary documents [test results, impact analysis of each merge request, the firmware source code]. Sometimes the UL asks for devices and validates the safety functionality in their lab. The UL team reviews the submitted documents offline and, during code review meetings, asks questions regarding changes that may impact safety-related functionality. Sometimes, the UL team requests hardware to evaluate basic EVSE faults [like CCID detection, welded contact, and more] and measures the time it takes to open the contactors in fault conditions. To comply with the standard, the EVSE must open its contactors within the threshold time defined by UL for each specific fault.
UL/IEC 60730 [Standard for Functional Safety]:
This standard focuses on increasing the safety of appliances with embedded control software and hardware. The manufacturer must find and eliminate risks of hazards caused by potential malfunctions. This certificate provides confidence to the user for the product and their safety. For EVSE products, this certification process mainly analyzes whether the charging current is increasing in case of hardware or software failure. Certain buyers require EVSE products to adhere to this standard as part of their compliance expectations.
Process:
After applying online for this certification, a UL representative is assigned to the product. After the introductory call, the manufacturer must provide basic product functionality documents, and the UL team guides what to analyze for hardware and software. As part of the process, the manufacturer refers to the complete schematic and documents the open and short behavior of each connection and GPIO pin that directly or indirectly controls the charging current. For software, the manufacturer follows the list provided by UL, which recommends analyzing scenarios such as interrupt stuck-at faults, register stuck-at conditions, stuck bits in non-volatile and volatile memory, spurious interrupts, timing issues, and internal communication bus faults. In periodic calls, the manufacturer team must explain and resolve UL queries. UL may also ask for EMI and Electromagnetic Compatibility (EMC) results that prove that the pilot Pulse Width Modulation (PWM) is not going to be affected because of electromagnetic interference. In case of any safety issues observed during the analysis, the manufacturer must fix them.
NTEP [National Type Evaluation Program] Certification:
The National Council on Weight and Measures (NCWM) of USA runs the National Type Evaluation Program (NTEP) to determine whether the device meets the criteria to sell to end users. This certification provides confidence to users that a device is manufactured in accordance with United States standards as adopted by NCWM. All devices sold in the United States for “legal for trade” purpose must have this evaluation completed; thus, it is also applicable to the EV charger that measures the consumed energy and generates bills. Currently, most states in the USA do not allow EVSE to be sold without NTEP or California Type Evaluation Program (CTEP) certification.
Process:
The manufacturer can apply for the NTEP certification online through the NCWM website. Like other certification entities, NTEP has special rates for members. Entire certification process is clearly mentioned on the website. An NTEP representative may visit the manufacturer’s lab on the first day of evaluation, followed by the next visit after 21 days. During these days, the manufacturer must conduct charging sessions 8 hours per day. On the last day of evaluation, the NTEP representative validates the energy data on the backend against the Tesco meter. The targeted EVSE reported energy must be within 1% of the actual energy consumption to pass this process.
If an evaluation process is delayed due to failure, the manufacturer has ninety days to resubmit the corrected device. If not, the evaluation is placed on hold. Upon a fourth failure, the NTEP administrator may close the application.
Energy Star Certification:
It is a very well-known certification as most people check the energy star rating before purchasing even a small electric device, and this certification has become more important for high-power devices.
At the time when I am writing this blog, the Energy Star certification is mandatory for AC chargers but optional for DC chargers in the USA.
Process:
To earn the Energy Star label for products, the manufacturers are required to sign a formal agreement with the Environmental Protection Agency (EPA) and the products must be third-party certified against strict performance requirements. Third-party certification ensures products have been evaluated and reviewed prior to being labeled.
Energy Star specification and the test process are available on the Energy Star official website. The manufacturer must validate the energy consumption using the certified energy meters like Yokogawa as explained in the specification, to get compliance certification.
OCA [Open Charge Alliance] Certification:
OCA certification process validates the compliance of the Open Charge Point Protocol (OCPP) implementation, assurance of interoperability, and flexibility. The vendors can select which OCPP feature they want to certify [like core, smart charging, and firmware management], and according to that, the product is evaluated. OCA has one software tool that can perform almost all tests, and is validated during the conformance process, so vendors can use that tool to pre-check their implementation.
Process:
The vendors can select the lab where they want to perform a conformance test and get the appointment. After that, the manufacturer must provide written product information, certification modules to be certified, and response timeouts claimed. The conformance process is derived according to the information provided in this form. The vendor team should be present during the compliance test process and resolve lab queries. After completion of the conformance evaluation, the lab shares data with OCA and then OCA issues a certificate. The best part of this certification is that the manufacturer can pre-validate their implementation using the OCA tool, and thus there is less chance of last-minute surprises.
UL 9741 [Standard for EV Power Export Equipment for Bidirectional]:
EVSE can also support the bidirectional power transfer feature, wherein it enables the flow of current from the EV back to the grid. Using this feature, the user can supply electricity to a home from the EV in case of grid power outage. This standard evaluates whether the bidirectional system of the EVSE is effectively communicating with the EV and maintains proper electrical isolation.
Process:
Please refer to this link for more information and reach out to UL for the detailed and updated test process.
FCC [Federal Communications Commission] Certification:
This is the most common mandatory certification for all the radio frequency emitting devices. FCC is an independent USA government agency overseen by Congress that ensures that electronic devices meet the regulatory standard. This certificate provides confidence to the user that the certified device works within the defined frequency range and power, and that it does not affect any other electronic devices.
Process:
The FCC team provides a list of tests to be performed, and someone from the manufacturer team is required to visit the FCC certified lab for their product evaluation. This certification process evaluates whether the device emits more than the expected value and does not cross the frequency band boundaries. This is the most common certification for all IOT devices, so we will not discuss this in detail.
Modbus Conformance Certification:
If the EVSE has Modbus functionality, then the manufacturer can also apply for this certification. Modbus is used for load management in the EVSE application, thus in this case the EVSE Modbus functionality must work efficiently, otherwise the users may end up with breaker tripping. Modbus.org evaluates and verifies this certificate.
Process:
The manufacturer shares the product with the latest features and Modbus map with the filled application form. This application form asks for product details, functionality to evaluate [TCP/RTU], Modbus register addresses, supported Modbus functions, firmware upgrade process, and so on. Once the product reaches the Modbus lab, it is allocated to one person who validates each register and failed cases. In case of any failure, they provide a chance to share updated firmware, and a re-evaluation is performed.
BACnet Conformance Certification:
If the EVSE product has BACnet functionality within, then this is one of the feathers that can be added to your cap. Just like Modbus conformance certification process explained above, the manufacturer sends the device with the latest firmware and documents. The entire BACnet functionality is evaluated in a BACnet certified lab.
Conclusion:
There are other UL/IEC standards/certifications available that are specific to EV and EVSE products that the manufacturers can use to create a unique identity. For the list of more applicable standards, please refer to this link. Apart from these UL/IEC standards there is a need to apply for OWAPS top 10 and penetration test to confirm cyber security immunity. OSS clearance is also required to confirm that the product is using third party tools under a valid license. That said, the manufacturer must consider all applicable standards/certification/tests at the initial phase to avoid last minute blockers.
eInfochips has strong competency in the design and development of AC/DC EV chargers. Our expertise in Embedded Industrial IoT device development, Hardware Design on different platforms, and Cyber Security has helped us to create meaningful value for customers across industry verticals including industrial metering devices, electric vehicle chargers, wearable devices, and medical equipment. To know more about our EVSE solutions and services, please contact us through our website www.einfochips.com.
