Project Name – Line 1
Project Name – Line 2 / Project Code #xxx-xxxxx
Month Day, Year
EYP, Inc – Proj No. xxxxxxx.xx

SECTION 26 2250 - LOW-VOLTAGE (HARMONIC MITIGATING) TRANSFORMERS

PART 1 - GENERAL

1.1  RELATED DOCUMENTS

  1. Drawings and general provisions of the Contract, including General and Supplementary Conditions and Division01 Specification Sections, apply to this Section.

1.2  SUMMARY

  1. This Section includes the following types of dry-type transformers rated 600V and less, with capacities up to 1000 kVA:
  2. Distribution transformers.
  3. Harmonic mitigating.

1.3  DEFINITIONS

  1. HMT: Harmonic mitigating transformers.
  2. Linear Load: A load (i.e., a motor, incandescent lamp, resistor) that does not influence the shape of the original sinusoidal current waveform but may change the relative timing (phase angle) between the sinusoidal voltage and current waveform.
  3. Nonlinear Load: A load (i.e. rectifier, arc, motor drive, switch-mode power supply, fluorescent lamp) that influences the shape of the current waveform resulting in a condition in which total harmonic distortion of current (THDI) is greater than total harmonic distortion of voltage (THDV). Because the current supplying a nonlinear load is interrupted by a switching action, the current contains frequency components (harmonics) that are multiples of the fundamental frequency.
  4. Total Harmonic Distortion of Current (THDi): A measure of the harmonic current distortion present in a system or sub-system defined as the ratio of the sum of all harmonic current frequency components to the fundamental current frequency component.
  5. Total Harmonic Distortion of Voltage (THDv): A measure of the harmonic voltage distortion present in a system or sub-system defined as the ratio of the sum of all harmonic voltage frequency components to the fundamental voltage frequency component.

1.4  MANDATORY BID PROCEDURES

  1. Based on the recommendations of The American Society of Heating, Refrigeration and Air-Conditioning Engineers (ASHRAE), The American Institute of Architects (AIA), Illuminating Engineering Society of North America (IESNA), U.S. Green Building Council (USGBC) and the U.S. Department of Energy (US DOE); the bid price for each low voltage, dry-type transformer specified for this project must be identified (priced) separately within the electrical bid and shall not be included in the bid pricing for other electrical distribution equipment, i.e. panel boards, switchgear, etc., that falls under Division 26 of the Standard AIA Specification Structure. If specified transformers are not separately identified in the bid pricing then the entire bid will be disqualified.
  2. Proposal Form: [Refer to Division 00, Section 000300 “Proposal Form”.] Submit completed proposal form at time of bid with transformers priced separately from all other electrical distribution equipment, i.e. panelboards, switchgear, circuit breakers, etc. in such a manner that the transformers and/or other items in the bid may be purchased separately.

1.5  ACTION SUBMITTALS

  1. Product Data: Submit the following information for review and approval by the engineer of record prior to delivery and installation of each transformer that is to be supplied for this project.
  2. Nameplate kVA rating.
  3. Nominal Voltage rating, primary and secondary.
  4. Winding configuration, primary and secondary.
  5. Core and coil materials.
  6. Taps, quantity and configuration.
  7. Dimensions.
  8. Weight.
  9. Accessories.
  10. Performance Characteristics:
  11. Frequency.
  12. Impedance.
  13. Insulation class.
  14. Temperature rise.
  15. Sound level.
  16. BIL rating.
  17. Inrush data.
  18. Accessories.
  19. Loss and efficiency data.
  20. Shop Drawings: Detail equipment assemblies and indicate dimensions, weights, loads, required clearances, method of field assembly, components, and location and size of each field connection.
  21. Wiring Diagrams: Power, signal, and control wiring.

1.6  INFORMATIONAL SUBMITTALS

  1. Manufacturer Seismic Qualification Certification: Submit certification that transformers, accessories, and components will withstand seismic forces defined in Section260548 "Vibration and Seismic Controls for Electrical Systems." Include the following:
  2. Basis for Certification: Indicate whether withstand certification is based on actual test of assembled components or on calculation.
  3. The term "withstand" means "the unit will remain in place without separation of any parts from the device when subjected to the seismic forces specified and the unit will be fully operational after the seismic event."
  4. Dimensioned Outline Drawings of Equipment Unit: Identify center of gravity and locate and describe mounting and anchorage provisions.
  5. Detailed description of equipment anchorage devices on which the certification is based and their installation requirements.
  6. Source quality-control test reports.
  7. Field quality-control test reports.

1.7  CLOSEOUT SUBMITTALS

  1. Operation and Maintenance Data: For transformers to include in emergency, operation, and maintenance manuals.

1.8  QUALITY ASSURANCE

  1. Manufacturer Qualifications:
  2. Transformer manufacturers proposing to submit a bid for harmonic mitigating transformers shall have a minimum of twenty years' experience in the design and manufacture of harmonic mitigating transformers. Manufacturing experience in the design and manufacture of general purpose transformers does not qualify.
  3. Manufacturer shall be ISO 9001 certified.
  4. Source Limitations: Obtain each transformer type through one source from a single manufacturer. Pricing for transformers must be provided separate from other distribution system equipment and must be clearly listed on the bid form based on manufacturer.
  5. Electrical Components, Devices, and Accessories: Listed and labeled as defined in NFPA70, Article100, by a testing agency acceptable to authorities having jurisdiction, and marked for intended use.
  6. Comply with IEEEC57.12.91, "Test Code for Dry-Type Distribution and Power Transformers."

1.9  COORDINATION

  1. Coordinate size and location of concrete bases with actual transformer provided. Cast anchor-bolt inserts into bases. Concrete, reinforcement, and formwork requirements are specified with concrete.
  2. Coordinate installation of wall-mounting and structure-hanging supports with actual transformer provided.

1.10  WARRANTY

  1. Manufacturer's Warranty: Manufacturer warrants that the product(s) delivered conforms to the specifications and is free from defects in material and workmanship for the Warranty Period(s) indicated below, pro-rated from the date of Substantial Completion, provided that the product(s) have not been misused, abused, altered, neglected, improperly installed or damaged.
  2. Warranty Period: Manufacturer agrees to repair or replace products that fail in materials or workmanship within specified warranty period.
  3. Terms and Conditions
  4. Harmonic Mitigating – High Efficiency Transformers: Twenty (20) years pro-rated, with standard limited liability clauses provided that the manufacturer participates in and approves of the product application indicated on the Drawings.
  5. Limit of Liability:
  6. Manufacturer’s overall liability is limited to the cost of the product or defective part.

PART 2 - PRODUCTS

2.1  GENERAL TRANSFORMER REQUIREMENTS

  1. Description: Factory-assembled and -tested, air-cooled units for 60-Hz service.
  2. Cores:
  3. Three-phase, common core construction with one leg per phase.
  4. Grain-oriented, non-aging silicon steel.
  5. Anti-vibration pads shall be installed between the core and the enclosure.
  6. All transformers112.5 kVA and above shall utilize a miter-cut core to achieve ultra-low, no-load losses and the core shall be constructed with no more than three laminations per vertical or horizontal group.
  7. Coils: Continuous windings without splices except for taps.
  8. Internal Coil Connections: Brazed type.
  9. Coil Material: [Copper] or [Aluminum].
  10. Voltage Class: 1.2 kV.
  11. BIL Rating: 10 kV
  12. Magnetic Field: 0.1 Gauss at a maximum of 18 inches.
  13. Losses and Efficiency:
  14. Linear load losses and efficiency:
  15. Linear losses and efficiency shall be determined in accordance with U.S. Department of Energy (DOE) Code of Federal Regulations (CFR) requirements as defined in Energy, 10 CFR. §431, Subpart K, Appendix A (2015) using the "Open Circuit and Short Circuit Test Method". Manufacturers shall provide proof of compliance Type Tests for each transformer type and kVA rating. Type Tests are required with each submission.
  16. Linear loss curves (0 percent to 100 percent full load) shall be provided for each transformer type and kVA rating. Linear losses at 0 percent, 15 percent, 25 percent, 35 percent, 50 percent, 75 percent and 100 percent of full load shall be easily identified on each transformer loss curve AND shall be identified separately in table or other form to the nearest thousandth of a kilowatt (kW).
  17. Linear efficiency curves (0 percent to 100 percent full load) shall be provided for each transformer type and kVA rating. Linear efficiency ratings at 0 percent, 15 percent, 25 percent, 35 percent, 50 percent, 75 percent, and 100 percent of full load shall be easily identified on each transformer efficiency curve and shall be identified separately in table or other form to the nearest one hundredth of one percent.
  18. Nonlinear load losses and efficiency:
  19. Currently, there are no recognized standards for “measuring” transformer losses and determining transformer efficiencies under nonlinear load conditions. Therefore, nonlinear losses and efficiencies must be calculated in accordance with IEEE Std. C57.110-2004, “IEEE Recommended Practice for Establishing Transformer Capability When Supplying Non-sinusoidal Load Currents”. Manufacturers shall provide proof of compliance calculations for each transformer type and kVA rating. Calculations are required with each submission.

1)  IEEE Std. C57.110-2004 enables any transformer manufacturer to utilize the known linear losses and efficiencies of their transformers, which must be obtained using the “Open Circuit and Short Circuit Test Method”, defined in Energy, 10 CFR. §431, Subpart K, Appendix A (2015), to calculate the nonlinear losses and efficiencies of those same transformers under any “specific” nonlinear load condition. For the purposes of this specification, a “specific” nonlinear load condition shall be characterized by the transformer’s load level (as a percentage of nameplate kVA rating), load K-Factor and FHL (Harmonic Loss Factor), load harmonic spectrum including harmonic magnitudes and load %THDi.

2)  Nonlinear load testing programs that incorporate the use of capacitors, inductors, resistors, rectifiers, switch-mode power supplies or other electronic loads in an effort to simulate perceived, real world nonlinear load conditions in a controlled manufacturing environment are not acceptable since (i.) these testing programs are unique to each manufacturer, (ii.) non-duplicable due to source impedance variations at each manufacturer’s facility and (iii.) highly inaccurate due to significant and unavoidable loss measurement and calculated efficiency errors that exist when using the "Power-In - Power-Out Method". As documented by ANSI/IEEE, when using the "Power-In - Power-Out Method" to determine input and output power characteristics, the loss measurement error may exceed plus or minus 51.6 percent and calculated efficiency error may exceed plus or minus 1.34 percent, even when using synchronized, revenue class CTs, VTs and Wattmeters.

3)  Additionally, nonlinear load testing programs receive no professional, technical or governmental oversight since there are no recognized nonlinear testing standards that can be used for reference. This inevitably gives manufacturers the liberty to develop their own unique testing protocols which cannot be compared and evaluated equally against other manufacturers’ who may have completely different testing protocols.

  1. Nonlinear loss curves (0 percent to 100 percent full load) shall be provided for each transformer type and kVA rating based on a “specific” nonlinear load condition characterized by having a 35% of nameplate kVA load, UL 1561 load K-Factor of K13, load harmonic spectrum equal to [1st-1.0, 3rd-0.150, 5th-0.320, 7th-0.250, 9th-0.080, 11th-0.150, 13th-0.125, 15th-0.040] and %THDi of 48.32%. Nonlinear losses at 0 percent, 15 percent, 25 percent, 35 percent, 50 percent, 75 percent and 100 percent of full load shall be easily identified on each transformer loss curve AND shall be identified separately in table or other form to the nearest thousandth of a kilowatt (kW).
  2. Nonlinear efficiency curves (0 percent to 100 percent full load) shall be provided for each transformer type and kVA rating based on the same “specific” nonlinear load condition used to calculate nonlinear losses (refer paragraph b. above). Nonlinear efficiency ratings at 0 percent, 15 percent, 25 percent, 35 percent, 50 percent, 75 percent and 100 percent of full load shall be easily identified on each transformer efficiency curve AND shall be identified separately in table or other form to the nearest one hundredth of one percent.

2.2  DISTRIBUTION TRANSFORMERS

  1. Harmonic Mitigating, Isolation Transformers for Medium K-Factor Loads (K-Factor Greater Than 4.0 and Less Than or Equal to 13.0 and THDi Greater Than 20 percent and Less Than or Equal to 40 Percent):
  2. Basis-of-Design Product: Subject to compliance with requirements, provide Power Quality International LLC, Type DV (ZS), with losses equal to or less than required by Energy, CFR 10 §431.196(a)(2) (2015) or comparable product.
  3. Harmonic mitigating transformers shall be fabricated according to the following:
  4. CSA C9-M.
  5. CSA22.2 No. 47.
  6. CSA C802.2.
  7. UL-1561
  8. ANSI C57.110
  9. NEMA ST-20
  10. Description:
  11. Single input, single output.
  12. Energy Efficiency: Low voltage, dry-type, harmonic mitigating, distribution transformers shall be high efficiency (PQI ZS efficiency option or equivalent) and therefore must meet or exceed all of the following loss and energy efficiency requirements:

1)  High Efficiency (ZS):

a)  Losses less than or equal to Energy, CFR 10 §431.196(a)(2) (2015) under 35 percent linear load conditions.

b)  Maximum losses and minimum efficiency under linear load conditions per Table 1 - ZS Linear, High Efficiency.

Table 1 - ZS Linear, High Efficiency
Max and Min Values for Losses and Efficiency for “High Efficiency” Transformers
Meeting Energy, CFR 10 §431.196(a)(2) (2015) Efficiency Levels Under Linear Loading /
kVA / No Load / 35% Load / Full Load /
Loss
(kW) / Eff.
(%) / Loss
(kW) / Eff.
(%) / Loss
(kW) / Eff.
(%) /
15 / 0.0566 / 0.0000 / 0.1132 / 0.9789 / 0.5185 / 0.9666
30 / 0.0946 / 0.0000 / 0.1892 / 0.9823 / 0.8668 / 0.9719
45 / 0.1280 / 0.0000 / 0.2561 / 0.9840 / 1.1733 / 0.9746
75 / 0.1864 / 0.0000 / 0.3727 / 0.9860 / 1.7077 / 0.9777
112.5 / 0.2512 / 0.0000 / 0.5025 / 0.9874 / 2.3021 / 0.9799
150 / 0.3027 / 0.0000 / 0.6054 / 0.9886 / 2.7737 / 0.9818
225 / 0.4218 / 0.0000 / 0.8437 / 0.9894 / 3.8655 / 0.9831
300 / 0.5196 / 0.0000 / 1.0392 / 0.9902 / 4.7612 / 0.9844
500 / 0.7590 / 0.0000 / 1.5181 / 0.9914 / 6.9552 / 0.9863

c)  Nonlinear losses and efficiency shall be based on the following:

i.  UL 1561 load K-Factor: K13

ii.  Harmonic Spectrum:

1st (1.0), 3rd (0.150), 5th (0.320), 7th (0.250), 9th (0.080), 11th (0.150), 13th (0.125), 15th (0.040).

iii.  THDi: 48.32%

d)  Maximum losses and minimum efficiency per Table 2 - ZS Nonlinear, High Efficiency, based on the nonlinear load conditions stated in paragraphs c) i., ii. and iii. above.

Table 2 - ZS Nonlinear, High Efficiency
Max and Min Values for Losses and Efficiency for High Efficiency Transformers
Under K13 Nonlinear Loading [THDi: 48.32% , Harmonic Spectrum: 1st (1.0), 3rd (0.150), 5th (0.320), 7th (0.250), 9th (0.080), 11th (0.150), 13th (0.125), 15th (0.040)] /
kVA / No Load / 35% Load / Full Load /
Loss
(kW) / Eff.
(%) / Loss
(kW) / Eff.
(%) / Loss
(kW) / Eff.
(%) /
15 / 0.0566 / 0.0000 / 0.1253 / 0.9767 / 0.6954 / 0.9557
30 / 0.0946 / 0.0000 / 0.2149 / 0.9799 / 1.2400 / 0.9603
45 / 0.1280 / 0.0000 / 0.2968 / 0.9815 / 1.7656 / 0.9622
75 / 0.1864 / 0.0000 / 0.4346 / 0.9837 / 2.6076 / 0.9664
112.5 / 0.2512 / 0.0000 / 0.5965 / 0.9851 / 3.6692 / 0.9684
150 / 0.3027 / 0.0000 / 0.7229 / 0.9864 / 4.4828 / 0.9710
225 / 0.4218 / 0.0000 / 1.0153 / 0.9873 / 6.3621 / 0.9725
300 / 0.5196 / 0.0000 / 1.2944 / 0.9878 / 8.4728 / 0.9725
500 / 0.7590 / 0.0000 / 1.9122 / 0.9892 / 12.6872 / 0.9753
  1. Configuration:

1)  kVA Rating: As indicated on drawings..