technical information - arc-fault circuit interrupter in

Technical Information

Arc-Fault Circuit Interrupter in the Sunny Tripower CORE1(STP 50-41)

AFCI-TI-en-10 | Version 1.0ENGLISH

Table of Contents SMA Solar Technology AG

Technical InformationAFCI-TI-en-102

Table of Contents1 Introduction................................................................................................................................... 3

2 Basic Information ......................................................................................................................... 3

3 Function......................................................................................................................................... 3

4 Activation ...................................................................................................................................... 3

5 Certification and Normative Requirements ............................................................................... 4

6 Hardware and Software Requirements..................................................................................... 5

7 Event Messages............................................................................................................................ 5

8 Frequently Asked Questions ....................................................................................................... 6

1 IntroductionSMA Solar Technology AG

Technical Information 3AFCI-TI-en-10

1 IntroductionPV systems that are built according to today's installation standards and with high-quality components are generallyvery safe. Nevertheless, in rare cases, faulty contact points in the PV array or the installation on the DC circuit cancause electric arcs, which can damage both the system and the building.When a PV inverter with an integrated arc-fault circuit interrupter (AFCI) is used, an electric arc in the PV array isdetected soon enough and extinguished by an interruption of the current.To give customers the highest level of safety, SMA Solar Technology AG has equipped the Sunny Tripower CORE1(STP 50-41) with an effective arc-fault circuit interrupter (AFCI).This Technical Information is for installers and system designers and describes the basic information as well as all thenecessary steps and prerequisites for using the new arc-fault circuit interrupter (AFCI).

2 Basic InformationIf an electric arc occurs in the DC installation of a PV system during feed-in operation, this causes a change in thecurrent and a typical interference spectrum. In this case, high-frequency portions are superimposed upon the normaloperating current. These two specified criteria are the basis for detecting an electric arc reliably.

3 FunctionWhen the arc-fault circuit interrupter (AFCI) of the inverter is activated, the current of all MPP trackers is monitoredduring grid feed-in. If a current phenomenon that is typical for electric arcs occurs (e.g. change in current, high-frequency portions), an electric arc is detected and the inverter immediately terminates the feed-in operation andreports this event. Stopping the feed-in operation interrupts the current flow on the DC circuit and extinguishes theelectric arc.

4 ActivationThe arc-fault-circuit interrupter (AFCI) can be activated by two operating modes:

• Automatic restart• Manual restart

To activate the arc-fault circuit interrupter (AFCI) in the desired operating mode, set a parameter in the Deviceparameter group. The setting can be made either on the user interface of the inverter or on a higher-levelcommunication device. The procedure for activating the various operating modes depends on the country data set ofthe device that was selected. For more information, see the operating manual of the inverter.

Automatic RestartWhen an electric arc is detected, the inverter interrupts the feed-in operation and reports the event. After a waitingperiod, the inverter starts automatically and resumes feed-in operation. If an electric arc occurs again, this procedure isrepeated.This operating mode avoids feed-in losses in the event of faulty activation, as the device automatically resumesoperation when the fault is no longer present. Nevertheless, it is recommended to have the PV array checked by aqualified person after a fault has been reported. This is especially the case if the error messages occur more frequently.

Manual RestartWhen an electric arc is detected, the inverter interrupts the feed-in operation and reports the event. The inverter goesinto inhibited operation. Resumption of feed-in operation does not take place automatically. It only occurs after thesystem operator has reset the operation inhibition. The exact procedure for resetting the operating inhibition after anarc fault has been detected is described in the operating manual of the inverter.

5 Certification and Normative Requirements SMA Solar Technology AG


5 Certification and Normative RequirementsArc-fault circuit interruption (AFCI) complies with the following industry standards:

UL 1699B Ed 1.1 STANDARD FOR SAFETY - Photovoltaic (PV) DC Arc-Fault Circuit ProtectionThe arc-fault circuit interruption (AFCI) has been copied completely and without modifications from theSunny Tripower CORE1 (STP xx-US-41), which is used for the US market. It therefore uses the UL 1699B Ed1.1certified method for arc fault detection.

Draft Standard IEC 63027 Ed1 (82/1636/CDV) - DC arc detection and interruption inphotovoltaic power systemsThe integrated arc-fault circuit interrupter (AFCI) already meets the requirements of Draft Standard IEC 63027 Ed1.Since complete test requirements are not yet available for this standard, compliance to the current state-of-the-art isindicated through a manufacturer's declaration. Please note that the compliance of the arc-fault circuit interrupter(AFCI) in the scope of IEC 62027 corresponds to the following "Arc Fault Protection Equipment (AFPE)" applicationclasses:

• F-I-AFPE-1-6-2• F-I-AFPE-2-3-2

These application classes must be observed during installation if this is carried out in the scope of IEC 63027 Ed1(82/1636/CDV).The IEC 63027 classification system describes the device type, the scope of coverage, and other important aspectsthat are relevant for testing and installation. This information must be provided by the manufacturer as a code. Theindividual features are separated by a dash. The following table provides an overview of how the classification isstructured:

1st positionScope of pro-tection

2nd positionImplementationmethod

3rd positionScope of func-tionality

4th positionMaximum num-ber of stringsper DC input

5th positionNumber of DCinputs per arcfault sensor(AFS)

6th positionNumber of inte-grated arc faultsensors (AFS)

F: The arc-faultmonitoring systemcovers the entirePV array up tothe DC inputs ofthe inverter.P: The entirePV array is cov-ered up to aCombiner Box.Not the main lineup to the inputterminals of theinverter.

I: Integrated solu-tion (e.g. in the in-verter)S: Stand-alonedeviceD: The functional-ity is achieved bya combination ofseveral devices.

AFPE: Completesolution. Both thedetection and thedisconnectionand interruptionof the electric arcare integrated.AFD: The productcan only detectthe electric arc,but cannot di-rectly disconnectand interrupt it.

Number of stringsthat may be con-nected per DC in-put in the particu-lar constellation.

Number of DC in-puts assigned toan arc fault sen-sor (AFS).

Total number ofarc fault sensors(AFS) per device.

6 Hardware and Software RequirementsSMA Solar Technology AG


The following figure shows the permitted connection options for the particular application classes.

String

AFS1

AFS2

A

B

C

D

E

F

AFS1

AFS2

Input STP 50-41F-I-AFPE-1-6-2

StringInput STP 50-41

F-I-AFPE-2-3-2

A

B

C

D

E

F

In the case of application class F-I-AFPE-2-3-2, an additional restriction applies. If only one DC input is assigned perMPP tracker and the arc-fault current interrupter (AFCI) is used at the same time, the maximum 16 A input current of theDC input must not be exceeded. In general, no more than 2 DC strings may be connected in the system in parallel.

6 Hardware and Software RequirementsThe following table contains an overview of the inverters equipped with the arc-fault protective function. SMA SolarTechnology AG will provide information about implementation in further devices in due time.

Inverter Type of device Firmware version

Sunny Tripower CORE1 STP 50-41 As of production start

Sunny Tripower CORE1-US STP 33-US-41STP 50-US-41STP 62-US-41

As of production startThe "Automatic restart" function isavailable after a software update toversion 3.12.2x.R

7 Event MessagesThe following event messages may occur:

Event number Message, cause and corrective measures

4301

Serial electric arc in string |s0| detected by AFCI moduleThe inverter has interrupted the grid feed-in because an electric arc has been detected.Corrective measures:

• Check the PV modules as well as the cabling in the affected string for damage.• If manual restart has been set, the operation inhibition due to the electric arc must be

reset in order to continue feed-in operation.

8 Frequently Asked Questions SMA Solar Technology AG


Event number Message, cause and corrective measures

4302

Serial electric arc in string |s0| detected by an AFCI module of the 2nd stringgroupAn electric arc in string D, E or F has been detected.Corrective measures:

• Check the PV modules as well as the cabling in the affected string for damage.• If manual restart has been set, the operation inhibition due to the electric arc must be

reset in order to continue feed-in operation.

8208

Interference level too highAn error occurred during the initialization of the AFCI. It is not guaranteed that the AFCI willfunction correctly. The device does not feed in.Corrective measures:

• Contact the Service.

8209

Signal level too lowAn error occurred during the initialization of the arc-fault circuit interrupter (AFCI). It is notguaranteed that the arc-fault circuit interrupter (AFCI) will function correctly. The device doesnot feed in.Corrective measures:

• Contact the Service.

8 Frequently Asked Questions

What is the correct operating mode for the arc-fault circuit interrupter?The correct setting corresponds to the guidelines and standards valid in the country in which it is used. Within thescope of UL 1699B Ed1.1 as well as IEC 63027, both operating modes can be activated. If possible, we recommendsetting the operating mode for n automatic restart. There are currently exceptions in Canada.

Is the arc-fault circuit interrupter activated or deactivated when delivered?That depends on the country of operation. In the case of inverters approved for the American market (STP xx-US-41),the arc-fault circuit interrupter is activated. In the case of inverters not approved for the American market (STP 50-41),the arc-fault circuit interrupter is currently deactivated.

Do I need to activate the arc-fault circuit interrupter?This basically depends on the regulations in the country in which it is used. The design of the system can also berelevant here (e.g. whether it is a roof-mounted system or an open-field system). Furthermore, there may be specialrequirements for the PV system that prescribe an arc-fault circuit interrupter.

8 Frequently Asked QuestionsSMA Solar Technology AG


An insurance company requires an arc-fault circuit interrupter for a PV system, can I use the onementioned in section (see Section 6, page 5)?Due to the manufacturer's declaration of the particular type of inverter equipped with the arc-fault circuit interrupter,please obtain approval from the insurance company. The person who installs the system is then responsible foractivating the function.

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