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This section describes the test procedures and requirements for equipment used to interconnect DER facilities with EDTI's distribution system. These include type testing, commissioning testing and periodic testing. The procedures listed rely heavily on those described in appropriate Underwriters Laboratory (UL), Institute of Electrical and Electronic Engineers (IEEE) and International Electrotechnical Commission (IEC) documents, most notably:

  • UL 1741 Standard for Safety for Static Inverters and Charge Controllers for Use in Photovoltaic Power Systems.
  • IEEE 929 Recommended Practice for Utility Interface of Photovoltaic (PV) Systems.

7.1 General


The DERP shall notify EDTI in writing at least two weeks before the initial energizing and start-up testing of the DERP's DER equipment. EDTI may witness the testing of any equipment and protective systems associated with the interconnection.

The tests described here are intended to provide assurance that the DERP's equipment will not adversely affect EDTI's distribution system and that a DER facility will cease to provide power to EDTI's distribution system under abnormal conditions.

The following sections also describe the process for certifying equipment. Once a DER unit or device has been certified under this certification process, it may be considered suitable for use as part of a DER facility interconnected with EDTI's distribution system. Generally, EDTI will not require a DERP to repeat the design review or test the protective functions of equipment that has been certified. It should be noted the certification process is intended to facilitate the DER facility interconnections. Certification is not a prerequisite to interconnect a DER facility. The use of non-certified equipment may be acceptable to EDTI, subject to testing and approval by EDTI as discussed in section 7.2.

These test procedures only apply to the devices and packages associated with the protection of the interconnection between the DER system and EDTI's facilities. Interconnection protection is usually limited to voltage relays, frequency relays, synchronizing relays, reverse current or power relays, and anti-islanding schemes. The testing of relays or devices associated specifically with the protection or control of the DER equipment is recommended, but not required unless they affect the interconnection protection.

Testing of protection systems shall include procedures to functionally test all protective elements of the system up to and including tripping of the DER and/or point of common coupling. Testing will verify all protective set points and relay/breaker trip timing. The tests and testing procedures shall align with the requirements specified in IEEE 1547.

At the time of production, all interconnecting equipment and digital relays must meet or exceed the requirements of ANSI/IEEE C62.41-2002 or IEEE C37.90.1-2012. If C62.41-2002 is used, the surge types and parameters shall be applied, as applicable, to the equipment's intended installation location.

7.2 Certification Criteria


Equipment tested and approved (or listed) by an accredited, nationally recognized testing laboratory (NRTL) as having met the type-testing requirements described in this document is considered to be certified equipment for purposes of interconnection with EDTI's distribution system. Certification may apply to either a prepackaged system or an assembly of components that address the necessary functions. Type testing may be done in the manufacturer's factory, in a test laboratory or in the field. At the discretion of the testing laboratory, field certification may apply only to the particular installation tested. In such cases, some or all of the tests may need to be repeated at other installations.

For non-certified equipment, some or all of the tests described in this document may be required by EDTI for each DER facility installation. The manufacturer, or another laboratory acceptable to EDTI, may perform these tests, and the test results must be submitted for EDTI's review and approval. Approval by EDTI for equipment used in a particular application does not guarantee EDTI's approval for use in other applications.

When equipment is certified by a NRTL, the NRTL shall provide to the manufacturer, at a minimum, a certificate with the following information for each device:

  1. Administrative
    • The effective date of certification or applicable serial number (range or first in series), and/or other proof that certification is current.
    • Equipment model number(s) of the certified equipment.
    • The software version used in the equipment, if applicable.
    • Test procedures specified (including date or revision number).
    • Laboratory accreditation (by whom and to what standard).

  2. Technical (as appropriate)
    • Device ratings (kW, kVA, V, amps, etc.).
    • Maximum available fault current in amps.
    • In-rush current in amps.
    • Trip points, if factory set (trip value and timing).
    • Trip point and timing ranges for adjustable settings.
    • Nominal power factor or range if adjustable.
    • Indication whether the device or system is certified for non-export and the method used (reverse power or underpower).
    • Indication whether the device or system is certified as anti-islanding.

It is the responsibility of the equipment manufacturer to ensure that certification information is made publicly available by the manufacturer, the testing laboratory or a third party.

7.3 Type Testing

Type testing is performed or witnessed once, by an independent testing laboratory for a specific protection package. Once a package meets the type test criteria described in this section, the design is accepted by EDTI. The type test must also determine whether the protection settings meet the guidelines in this document. All interconnection equipment must include a type test procedure as part of the documentation. If any changes are made to the hardware, software, firmware or verification test procedures, the manufacturer must notify the independent testing laboratory to determine what, if any, parts of the type testing must be repeated. Failure of the manufacturer to notify the independent test laboratory of changes may result in the withdrawal of approval and the disconnection of units installed since the change was made.
7.3.1 Inverters

Static power inverters, at the time of production, must meet or exceed all of the type tests and requirements appropriate for a utility interactive inverter as specified in UL 1741 and IEEE 929. These requirements may also be applied to inverters used with electric energy sources other than photovoltaic systems. All inverters must be anti-islanding as defined by IEEE 929.

Inverter devices must also pass the following additional type tests to:

7.3.2 Synchronous Generators

Synchronous generator devices must pass the following type tests to:

7.3.3 Induction Generators

Induction generator devices must pass the following type tests to:

7.3.4 Anti-Islanding Test
​Interconnection protective devices must pass the anti-islanding test procedure described in section 8.4.1 and IEEE 929.
7.3.5 Export Limit Test
​Interconnection protective devices must pass an export limit test. An example of a test procedure is included in Appendix VI, 1. Export Limit Test Procedure.
7.3.6 In-Rush Current Test
​DER equipment that uses EDTI's distribution system to operate as a motor during start-up must be tested to determine the maximum current drawn during this start-up process. The resulting in-rush current is used to estimate the starting voltage drop. An example of a test procedure is included in Appendix VI, 2. In-Rush Current Test Procedure.
7.3.7 Synchronization Test
For synchronous generators and inverters capable of operating as a voltage source, a synchronization test must be performed to verify that the generator synchronizes within the specified voltage/frequency/phase angle requirements as described in section 3.2.2. An example of a test procedure is included in Appendix VI, 3. Synchronization Test Procedure.

7.4 Commissioning Testing


A commissioning test of the DERP's DERs and interconnection facilities will be performed before interconnection. As part of the commissioning process, the DERP shall provide EDTI with all test reports and the relay calibration reports for the DERs and interconnection switchgear.

The commissioning test, where required, will be performed onsite to verify protective settings and functionality as per EDTI relay test procedures. Upon initial parallel operation of a DER facility, or any time interconnection hardware or software is changed and may affect the functions listed below, a commissioning test must be performed by qualified personnel. Qualified personnel include professional engineers and certified technicians or licensed electricians with experience and training in testing protective equipment. The commissioning test must be performed in accordance with the manufacturer's recommended test procedure to prove that facilities adhere to the requirements of this document. EDTI has the right to witness commissioning tests as described below, or to require written certification by the installer describing which tests were performed and their results. Any exemptions from performing a commissioning test must be agreed upon in writing by EDTI.

Functions to be tested during commissioning, particularly with respect to non-certified equipment, may consist of the following:

  1. Overvoltage and undervoltage.
  2. Overfrequency and underfrequency.
  3. Anti-islanding function (if applicable).
  4. Export limit function (if applicable).
  5. Inability to energize dead line.
  6. Time delay on restart after utility source is stable.
  7. Utility system fault detection (if used).
  8. Synchronizing controls (if applicable).
  9. Other interconnection protective functions that may be required as part of the Interconnection Operating and Maintenance Agreement.

Other checks and tests required include:

  1. Verification of final protective settings.
  2. Trip test.
  3. On-load test.
7.4.1 Certified Equipment

DER facilities that are judged to have little or no potential impact on EDTI's distribution system need only incorporate certified equipment that, at a minimum, has passed its type tests. For such DER facilities, it is necessary to perform only the following tests:

  1. Protection settings that have been changed after factory testing will require field verification. Tests will be performed using secondary injection, applied waveforms, a simulated utility or, if none of the preceding tests are possible and the unit provides discrete readouts of the settings, a settings adjustment test to show that the device trips at the measured (actual) utility voltage or frequency.
  2. The anti-islanding function, if provided, will be checked by operating a load-break disconnect switch or circuit breaker to verify that the interconnection equipment ceases to energize its output terminals and does not restart until after the required time delay after the switch is closed.
  3. The export limit function will be tested using secondary injection techniques. Alternatively, this function may be tested by adjusting the generating facility output and local loads to verify that the applicable export limit criterion (such as reverse power or minimum power) is met.

An interconnection review study is conducted when a DERP submits a DER interconnection application. The study may impose additional components or additional testing.

7.4.2 Non-Certified Equipment
​Non-certified equipment shall be subject to the appropriate tests specified by EDTI. With EDTI's approval, these tests may be performed in the factory, in the field as part of commissioning or both. EDTI, at its discretion, may also approve a reduced set of tests for a particular application or if, for example, EDTI determines that it has sufficient familiarity with the equipment.
7.4.3 Verification of Settings
​If protective function settings have been adjusted as part of the commissioning process, then following the completion of such testing, the DERP shall confirm that all devices are set to EDTI-approved settings. This step shall be documented in the relay operation order certified by a professional engineer.
7.4.4 Trip Tests

Interconnection protective devices (e.g., reverse power relays) that have not previously been tested as part of the interconnection system with their associated interrupting devices (e.g., contactor or circuit breaker) shall be trip tested during commissioning. The trip test shall be adequate to prove that the associated interrupting devices open when the protective devices operate.

Interlocking circuits between protective devices and between interrupting devices shall be similarly tested unless they are part of a system that has been tested and approved during manufacture.

7.4.5 On-Load Tests

Interconnection protective devices that have not previously been tested as part of the interconnection system with their associated instrument transformers or that are wired in the field shall be given an on-load test during commissioning. This test will verify proper wiring, polarity, sensing signals, CT/PT ratios and operation of the measuring circuits. The on-load test shall be made with the power system energized and carrying a known level of voltage and current. The magnitude and phase angle of each alternating-current (AC) voltage and AC current connected to the protective device will be measured and the results compared to expected values.

For protective devices with built-in metering functions that report current and voltage magnitudes and phase angles, or magnitudes of current, voltage, and real and reactive power, the metered values can be compared to the expected values. Otherwise, calibrated portable ammeters, voltmeters and phase-angle meters shall be used.

7.4.6 Switchgear and Metering
EDTI reserves the right to witness the testing of installed switchgear and metering. The DERP shall notify EDTI at least 10 working days before any testing.

7.5 Periodic Testing


The periodic testing, calibration and maintenance of DERs and interconnection facilities shall be carried out in accordance with a maintenance schedule agreement between the DERP and EDTI. This includes the protective relaying, controls and automations. The DERP shall maintain periodic test reports or a log for inspection by EDTI. At agreed intervals, the DERP shall submit to EDTI for review the maintenance, test and calibration reports as a condition of continuing the interconnection agreement. EDTI may elect to check the settings and operation of the DERP's protective relaying under the maintenance schedule agreement, as it deems appropriate.

Any system that depends upon a battery for trip power shall be checked and logged once per month for proper voltage, or monitored continuously.