SECTION 16461

DRY TYPE TRANSFORMERS

PART 1 GENERAL

SECTION INCLUDES

Dry type two winding transformers.

Dry type autotransformers.

Dry type buck and boost transformers.

Dry type isolation transformers.

Transformer Distribution Center.

RELATED SECTIONS

Section 16111 - Conduit: Flexible conduit connections.

Section 16170 - Grounding and Bonding.

Section 16190 - Supporting Devices.

REFERENCES

NEMA ST 1 - Specialty Transformers

NEMA ST 20 - Dry Type Transformers for General Applications.

NFPA 70 - National Electrical Code.

SUBMITTALS

Submit under provisions of Section [01300] [_____].

Product Data: Provide outline and support point dimensions of enclosures and accessories, unit weight, voltage, KVA, and impedance ratings and characteristics, tap configurations, insulation system type, and rated temperature rise.

Test Reports: Indicate loss data, efficiency at 25, 50, 75 and 100 percent rated load, and sound level.

Manufacturer's Instructions:	Indicate application conditions and limitations of use stipulated by Product testing agency specified under Regulatory Requirements. Include instructions for storage, handling, protection, examination, preparation, installation, and starting of Product.

Manufacturer's Certificate: Certify that Products meet or exceed specified requirements.

QUALITY ASSURANCE

Perform Work in accordance with NECA Standard of Installation.

Maintain [one copy] [[____] copies] of [each] document on site.

QUALIFICATIONS

Manufacturer: Company specializing in manufacturing Products specified in this Section with minimum [three] [_____] years [documented] experience.

REGULATORY REQUIREMENTS

Conform to requirements of NFPA 70.

Furnish products listed and classified by [UL] [testing firm acceptable to authority having jurisdiction] as suitable for purpose specified and shown.

DELIVERY, STORAGE, AND HANDLING

Store, protect, and handle products to site under provisions of Section [01600] [______].

Deliver transformers individually wrapped for protection and mounted on shipping skids.

Accept transformers on site. Inspect for damage.

Store in a clean, dry space.	Maintain factory wrapping or provide an additional heavy canvas or heavy plastic cover to protect units from dirt, water, construction debris, and traffic.

Handle in accordance with manufacturer's written instructions. Lift only with lugs provided for the purpose. Handle carefully to avoid damage to transformer internal components, enclosure, and finish.

PART 2 PRODUCTS

TWO-WINDING TRANSFORMERS

Manufacturers:

[________________________________] Model [_________].

[________________________________] Model [_________].

[________________________________] Model [_________].

Substitutions: Under provisions of Section [01600] [_____].

Description:	NEMA ST 20, factory-assembled, air cooled dry type transformers [, ratings as indicated.]

Insulation system and average winding temperature rise for rated KVA as follows:

1-15 KVA: Class 185 with [80] [115] degrees C rise.

16-500 KVA: Class 220 with [80] [115] [150] degrees C rise.

Case temperature: Do not exceed [35] [_____] degrees C rise above ambient at warmest point.

Winding Taps:

Transformers Less than 15 KVA: Two 5 percent below rated voltage, full capacity taps on primary winding.

Transformers 15 KVA and Larger: NEMA ST 20.

Sound Levels: [NEMA ST 20.] [Maximum sound levels are as follows:

1-5 KVA: [__] dB.

6-25 KVA: [__] dB.

26-150 KVA: [__] dB.

151-225 KVA: [__] dB.

226-300 KVA: [__] dB.

301-500 KVA: [__] dB.

Basic Impulse Level: [10 KV.] [10 KV for transformers less than 300 KVA, 30 KV for transformers 300 KVA and larger.]

Ground core and coil assembly to enclosure by means of a visible flexible copper grounding strap.

Mounting: Suitable for [wall] [, floor] [, or] [trapeze] mounting, except transformers larger than 75 KVA, suitable for [floor] [or] [trapeze] mounting.

Coil Conductors: Continuous windings with terminations brazed or welded.

Enclosure: NEMA ST 20; [Type 1.] [Type 3R [ventilated] [non-ventilated].] Provide lifting eyes or brackets.

Isolate core and coil from enclosure using vibration-absorbing mounts.

Nameplate: Include transformer connection data [and overload capacity based on rated allowable temperature rise.]

AUTOTRANSFORMERS

Manufacturers:

[________________________________] Model [_________].

[________________________________] Model [_________].

[________________________________] Model [_________].

Substitutions: Under provisions of Section [01600] [_____].

Description:	NEMA ST 20, factory-assembled, air cooled dry type autotransformers [, ratings as indicated.]

Insulation system and average winding temperature rise for rated KVA as follows:

10-15 KVA:	Class 185 with 115 degrees C rise.

16-500 KVA: Class 220 with 150 degrees C rise.

Case temperature: Do not exceed [35] [_____] degrees C rise above ambient at warmest point.

Winding Taps:

Transformers Less than 15 KVA: Two 5 percent below rated voltage, full capacity taps on primary winding.

Transformers 15 KVA and Larger: NEMA ST 20.

Sound Levels: [NEMA ST 20.] [Maximum sound levels are as follows:

1-5 KVA: [__] dB.

6-25 KVA: [__] dB.

26-150 KVA: [__] dB.

151-225 KVA: [__] dB.

226-300 KVA: [__] dB.

301-500 KVA: [__] dB.

Use three-legged core construction.

Ground core and coil assembly to enclosure by means of a visible flexible copper grounding strap.

Mounting: Suitable for [wall] [, floor] [, or] [trapeze] mounting, except transformers larger than 75 KVA, suitable for [floor] [or] [trapeze] mounting.

Coil Conductors: Continuous windings with terminations brazed or welded.

Enclosure: NEMA ST 20; [Type 1.] [Type 3R [ventilated] [non-ventilated].] Provide lifting eyes or brackets.

Isolate core and coil from enclosure using vibration-absorbing mounts.

Nameplate: Include transformer connection data.

BUCK AND BOOST TRANSFORMERS

Manufacturers:

[________________________________] Model [_________].

[________________________________] Model [_________].

[________________________________] Model [_________].

Substitutions: Under provisions of Section [01600] [_____].

Description:	NEMA ST 1, factory-assembled, dry type two winding buck and boost transformers [, ratings as indicated.]

Insulation system and average winding temperature rise for rated KVA as follows:

0.25-2 KVA: Class 185 with 80 degrees C rise.

3-7.5 KVA:	Class 220 with [80] [115] degrees C rise.

Mounting: Wall.

Coil Conductors: Continuous windings.

Lugs: Suitable for terminating conductors sized for full load ampacity of transformer unit when operating in buck- and-boost configuration shown.

Enclosure: NEMA ST 1, Type 1.

Isolate core and coil from enclosure using vibration-absorbing mounts.

Nameplate: Include transformer connection data.

ISOLATION TRANSFORMERS

Manufacturers:

[________________________________] Model [_________].

[________________________________] Model [_________].

[________________________________] Model [_________].

Substitutions: Under provisions of Section [01600] [_____].

Description:	NEMA ST 20, factory-assembled, air cooled dry type shielded isolation transformers [, ratings as indicated.]

Insulation system and average winding temperature rise for rated KVA as follows:

10-15 KVA:	Class 185 with 115 degrees C rise.

16-500 KVA: Class 220 with 150 degrees C rise.

Case temperature: Do not exceed [50] [_____] degrees C rise above ambient at warmest point.

Winding Taps:

Transformers Less than 15 KVA: Two 5 percent below rated voltage, full capacity taps on primary winding.

Transformers 15 KVA and Larger: NEMA ST 20.

Sound Levels: [NEMA ST 20.] [Maximum sound levels are as follows:

1-5 KVA: [__] dB.

6-25 KVA: [__] dB.

26-150 KVA: [__] dB.

151-225 KVA: [__] dB.

226-300 KVA: [__] dB.

301-500 KVA: [__] dB.

Basic Impulse Level: [10 KV.] [10 KV for transformers less than 300 KVA, 30 KV for transformers 300 KVA and larger.]

Ground core and coil assembly to enclosure by means of a visible flexible copper grounding strap.

Provide electrostatic winding shield with separate

insulated grounding connection.

Mounting: Suitable for [wall] [, floor] [, or] [trapeze] mounting, except transformers larger than 75 KVA, suitable for [floor] [or] [trapeze] mounting.

Coil Conductors: Continuous windings with terminations brazed or welded.

Enclosure: NEMA ST 20, [Type 1.] [Type 3R [ventilated] [non-ventilated].] Provide lifting eyes or brackets.

Isolate core and coil from enclosure using vibration-absorbing mounts.

Nameplate: Include transformer connection data.

TRANSFORMER DISTRIBUTION UNITS

Manufacturers:

[________________________________] Model [_________].

[________________________________] Model [_________].

[________________________________] Model [_________].

Substitutions: Under provisions of Section [01600.] [_____.]

Description:	NEMA ST20, transformer distribution unit with integral primary, secondary, and branch circuit breakers.

SOURCE QUALITY CONTROL

Provide testing of transformers under provisions of Section [01400.] [______.]

Provide production testing of each unit in accordance with NEMA ST20.

PART 3 EXECUTION

EXAMINATION

Verify condition under provisions of Section [01039] [_____].

Verify that surfaces are suitable for installing transformer supports.

PREPARATION

Provide concrete pad under provisions of Section [03300.] [_____.]

INSTALLATION

Install Products in accordance with manufacturer's instructions.

Set transformer plumb and level.

Use flexible conduit, under the provisions of Section 16111, 2 ft (0.6 M) minimum length, for connections to transformer case. Make conduit connections to side panel of enclosure.

Mount transformers on vibration isolating pads suitable for isolating the transformer noise from the building structure.

Provide seismic restraints.

Provide grounding and bonding in accordance with Section 16170.

FIELD QUALITY CONTROL

Field [inspection and] testing will be performed under provisions of Section [01400] [_____].

Check for damage and tight connections prior to energizing transformer.

Measure primary and secondary voltages and make appropriate tap adjustments.

END OF SECTION