NFPA 110: Acceptance Testing

It is crucial to know that the installed system will perform as expected without waiting for the first time that the power goes out.  Therefore, acceptance testing is necessary to confirm that the system will perform as required.

Upon completion of the installation of the EPSS, the EPS shall be tested to ensure conformity to the requirements of the standard with respect to both power output and function. (7.13.1) These installation acceptance tests are applied to the new components of an EPSS, whether installed for a new or existing system. 

An on-site acceptance test shall be conducted as a final approval test for all EPSSs. (7.13.2) Only systems that have been tested and have exhibited the ability to function as designed have met the requirements of NFPA 110.  The test shall be conducted after completion of the installation with all EPSS accessory and support equipment in place and operating.

The authority having jurisdiction (AHJ) shall be given advance notification of the time of the acceptance test so that the authority can witness the test. (7.13.3) It is in the best interests of all parties that the AHJ be present during the test. After passing the tests, the equipment will be warranted and commissioned by the AHJ for use as an emergency power system.

The EPSS shall perform within the limits specified in NFPA 110. (7.13.4) These requirements are for acceptance testing of the initial EPSS at a new and unoccupied building and of a new EPSS at an existing facility. 

On-Site Installation Acceptance Test

7.13.4.1 - The on-site installation acceptance test shall be conducted in accordance with Sections 7.13.4.1.1 through 7.13.4.1.4 Note: The test is performed on the completely installed EPSS with the test load supplied through the load terminals of the transfer equipment. This requirement applies to the entire EPSS, whether supplied by a single or multiple emergency power supplies (generator sets). A cold start condition means typical ambient temperature with jacket water heaters functioning.

7.13.4.1.1 - In a new and unoccupied building or facility, with the prime mover in a cold start condition and the emergency load at operating level, a normal power failure shall be initiated by opening all switches or circuit breakers supplying the normal power to the building or facility.

7.13.4.1.2 - In an existing occupied building or facility, with the prime mover in a cold start condition and the emergency load at operating level, a normal power failure shall be simulated by operating at least one transfer switch test function or initiated by opening all switches or breakers supplying normal power to all ATSs that are part of the EPSS being commissioned by this initial acceptance test.

7.13.4.1.3 - When the EPSS consists of paralleled EPSs, the system control function for paralleling and load shedding shall be verified in accordance with system design documentation. Note: This requirement was added in 2016 to verify that the control functions and any load shedding necessary for the parallel system will operate as designed.

7.13.4.1.4 - The tests conducted in accordance with 7.13.4.1.1 and 7.13.4.1.2 shall be performed in accordance with (1) through (12). Note: The items listed below are not individual tests; the acceptance test is the total of the items conducted as one test.

1. When the EPSS consists of paralleled EPSs, the quantity of EPSs intended to be operated simultaneously shall be tested simultaneously with building load for the test period identified in 7.13.4.1.4(10).
2. The test load shall be all loads that are served by the EPSS. There is no minimum loading requirement for this portion of the test. Note: This test is commonly referred to as a Block Load Test.
3. The time delay on start shall be observed and recorded.
4. The cranking time until the prime mover starts and runs shall be observed and recorded.
5. The time taken to reach operating speed shall be observed and recorded.
6. The engine start function shall be confirmed by verifying operation of the initiating circuit of all transfer switches supplying EPSS loads.
7. The time taken to achieve a steady-state condition with all switches transferred to the emergency position shall be observed and recorded.
8. The voltage, frequency, and amperes shall be recorded.
9. Where applicable, the prime mover oil pressure and water temperature shall be recorded.
10. The load test with building load, or other loads that simulate the intended load as specified in Section 5.4 (e.g. ability to pick up and carry load), shall be continued for not less than 1.5 hours, and the run time shall be recorded. 
11. When normal power is restored to the building or facility, the time delay on retransfer to normal power for each switch with a minimum setting of 5 minutes shall be recorded.
12. The time delay on the prime mover cooldown period and shutdown shall be recorded.

7.13.4.2 - After completion of the test performed in 7.13.4.1 above, the prime mover (engine) shall be allowed to cool for not less than 5 minutes.

Full Load Test

7.13.4.3 - A load shall be applied for a 2-hour, full load test. The building load shall be permitted to serve as part or all of the load, supplemented by a load bank of sufficient size to provide a load equal to 100 percent of the nameplate kW rating of the EPS, less applicable derating factors for site conditions. Note: This test is commonly referred to as a Step Load Test.

7.13.4.3.1 - This full-load test shall be initiated after the test specified in 7.13.4.1.4 by any method that starts the prime mover and, upon reaching rated rpm, picks up not less than 30 percent of the nameplate kW rating for the first 30 minutes, not less than 50 percent of the nameplate kW rating for the next 30 minutes, and 100 percent of the nameplate kW rating for the next 60 minutes, less applicable derating factors for site conditions. Note: There is a difference between prime and standby ratings and there can be a significant difference when calculating 30% of nameplate. It is important to verify the rating before the test.

7.13.4.3.2 - A unity power factor shall be permitted for on-site testing, provided that rated load tests at the rated power factor have been performed by the manufacturer of the EPS prior to shipment. Note: If the factory test was not specified or performed at the rated power factor (typically 0.8), the on-site test may require reactive load bank testing to comply. It is important to specify rated load tests in the design documents and order optional factory testing, if necessary.

7.13.4.3.3 - Where the EPS is a paralleled multi-unit EPS, each unit shall be permitted to be tested individually at its rating. Note: Running the entire system at one time is acceptable, but it is permitted to test each EPS individually.

7.13.4.3.4 - The data specified in 7.13.4.1.4(4) (i.e. Cranking Time), 7.13.4.1.4(5) (i.e. Time to Reach Operating Speed), and 7.13.4.1.4(7) (i.e. Time to Full Load Acceptance) shall be recorded at first load acceptance of the test period identified in 7.13.4.1.4(10) (i.e. Type 10 = 10 sec.).

7.13.4.3.5 - The data specified in 7.13.4.1.4(8) (i.e. Voltage, Frequency, and Amperage) and 7.13.4.1.4(9) (i.e. Oil Pressure and Water Temperature) shall be recorded at first load acceptance and every 15 minutes thereafter until the completion of the test period identified in 7.13.4.1.4(10) (i.e. Typically 2 hours).

Cycle Crank Test

7.13.4.4 - Any method recommended by the manufacturer for the cycle crank test shall be utilized to prevent the prime mover (engine) from running.

7.13.4.4.1 - The control switch shall be set at “run” to cause the prime mover to crank.

7.13.4.4.2 - The complete crank/rest cycle specified in 5.6.4.2 and Table 5.6.4.2 (i.e. Cycle Crank (3 cycles) = 75 sec. and Continuous Crank = 45 sec.) shall be observed.

7.13.4.4.3 - The battery charge rate shall be recorded at 5-minute intervals for the first 15 minutes or until charge rate stabilization.

Safety Indications and Shutdowns Test

7.13.4.5 - All safeties specified in 5.6.5 (i.e. Control Functions) and 5.6.6 (i.e. Remote Controls and Alarms) shall be tested on site as recommended by the manufacturer. Exception: It shall be permitted for the manufacturer to test and document overcrank, high engine temperature, low lube oil pressure and overspeed safeties prior to shipment.

Factory Acceptance Testing

7.13.4.6 - Items (1) through (4) shall be made available to the authority having jurisdiction (AHJ) at the time of the acceptance test:

1. Evidence of the prototype test as specified in 5.2.1.2 (for Level 1 systems) 
2. A certified analysis as specified in 5.6.10.2 (i.e. torsional vibration compatibility
3. A letter of compliance as specified in 5.6.10.5 (i.e. NFPA 110 compliance certification)
4. A manufacturer’s certification of a rated load test at rated power factor with the ambient temperature, altitude, and fuel grade recorded

Rolls-Royce mtu generator sets undergo factory acceptance testing that includes prototype testing and load testing at unity power factor (Max Load at 1.0 PF) and rated power factor (Max Load at .08 PF) as part of their Performance Assurance Certification.  See Factory Acceptance Testing for more information about the manufacturer’s test procedures.