SECTION III SPECIFICATIONS Three Phase Pad Mount Transformers (Dead Front Configuration) A.
General Electrical and Mechanical Features: 1. New, not remanufactured. 2. Three-phase, 60 HZ 3. Mineral-oil filled, self-cooled, pad-mounted type distribution transformer, kVA rating as shown on bid form, primary voltage 12.47 kV volts DELTA, and with secondary voltage as shown on bid form. Transformer shall be suitable for connection to a 12.47 kV WYE, multigrounded distribution system. 4. Secondary voltage as indicated on bid form. 5. Impedance as per below: 75kVA to 500kVA – 2.5% to 3.5% 750kVA and above – as per ANSI C57.12.26 (5.3% to 6.2%) 6. The transformer shall meet all applicable requirements of ANSI C57.12.26 except as otherwise specified herein. 7. The maximum temperature rise above ambient at 100% KVA load shall not exceed 65 degrees C.
B.
The primary connection shall be dead front and shall consist of six (6) 600A, fully rated, non-loadbreak bushings. For each incoming circuit, bushings shall be horizontally or diagonally-mounted side by side. Bushings shall be labeled as H1A, H2A, H3A (left) and H1B, H2B, H3B (right). 600A bushings shall be equipped with brass or tinned copper studs only – aluminum is not acceptable.
C.
Three internal 600A load break switches, hot-stick operable from the front of the transformer, to be located as shown in Figure 1. The switches shall be configured as follows: 1. Line Switch A a. Open (Off) – The internal 12.5kV buswork is not energized from Source A. b. Closed (On) – The internal 12.5kV buswork is energized from Source A. 2. Line Switch B a. Open (Off) – The internal 12.5kV buswork is not energized form Source B. b. Closed (On) – The internal 12.5kV buswork is energized from Source B. 3. Transformer Switch a. Open (Off) – The transformer is not energized from the internal 12.5kV buswork.
Revised 7/29/11
b.
Closed (On) – The transformer is energized from the internal 12.5kV buswork. The operators for the internal 600A load break switches shall be mounted in the primary compartment of the transformer. The internal 600A load break switches shall be mounted in such a way as to provide full access for hot-stick operation with a full complement of conductors on all of the available primary bushings. D.
Cable accessory parking stands shall be located adjacent to the bushing wells with a minimum of 6.5 inches from the center line of the bushing to the center line of the parking stand.
E.
The transformer windings shall be protected by three (3) dual sensing Bay-O-Net type fuses located in the primary compartment. All Bay-O-Net fuseholders shall be provided with plastic spill pans. The transformer shall include three spare fuses of operation at 12.47kV.
F.
The transformer shall be equipped with an automatic pressure relief device, pressure gauge, oil level gauge and an oil temperature gauge with resettable drag needles.
G.
WYE connected secondaries shall have the secondary neutral brought out in the secondary compartment through a fully insulated bushing (“XO”) and equipped with a removable full ampacity ground strap.
H.
The four (4) low voltage bushings shall be fitted with appropriately sized spade type terminals. Secondary bushing spades shall be designed in a staggered arrangement with a minimum of 5 ½” horizontal clearance between spades and 3 ¾” clearance from any sidewall. The transformer must meet the requirements of ANSI 57.12.22-1989, Fig. 3 for low voltage terminal arrangements and minimum dimensions.
I.
The transformer shall be equipped with a minimum of two (2) two-hole NEMA ground pads located in the lower portion of the compartments, one in the primary compartment and one in the secondary compartment. Ground pads shall be ½ inch 13NC tapped holes, 7/16” deep. Ground pads shall be capped before painting.
J.
The transformer shall be fitted with a one-inch upper filter press and filling plug or cap and a one-inch drain valve with built-in sampling device. Such drain valves shall be located at the bottom of the low voltage compartment.
K.
Transformer Termination Compartment Construction Requirements:
Revised 7/29/11
1. 2. 3. 4. 5.
6.
7.
8. 9. 10.
The transformer shall be of compartmental type construction with completely separate compartments for both the primary and the secondary. The primary and secondary compartments shall be side by side, with the secondary compartment on the right side when facing the transformer front compartment. The primary and secondary compartments shall be completely enclosed with removable front sills and doors. Doors are to be removable only in the fully-open position. The high voltage compartment door shall be of the interlock type and shall be secured by a ½ in. stainless steel pentahead bolt held in the center frame which is accessible only after the low voltage door is opened. The low voltage compartment door shall include a handle with a two (2) point locking arrangement equipped with provisions for pad-locking. The secondary compartment door handle to include a spring loaded captive stainless steel pentahead bolt which will require loosening of the bolt to permit operation of the handle. An instruction nameplate shall be located on the inside of the low voltage compartment and will clearly indicate the following: a. The connection diagram. b. The location of the protective devices. c. All other pertinent information related to the unit. Footprint of transformer shall not exceed the following maximum dimensions: a. 78 inches wide, including radiators. b. 70 inches deep, including radiators. Stainless steel is to be used for all metal in contact with the foundation (sill, side panels, and false bottom of tank area). All exposed hardware shall be stainless steel. Manufacturer must furnish certification that the transformer will meet ANSI Standard on enclosure security standards. The tank wall inside the compartment shall be painted light grey.
L.
The transformer tank shall include a fully gasketed cover that is fully detachable for access to the interior of the tank, or approved alternate. It shall have a wraparound guard that is removable only when the compartment doors are opened and shall enclose the tank cover nuts, or approved alternate.
M.
The transformer shall be equipped with lifting lugs or other suitable means for safely lifting the unit.
N.
Each transformer shall meet, or exceed, Western Underground Committee Guide 2-13 for security and tamper-resistant operation.
O.
The transformer shall be provided with all required safety stickers and warning labels.
Revised 7/29/11
P.
The transformer coating shall meet or exceed the latest EEI finishing guidelines for pad mounted equipment and the successful vendor must provide certified test reports insuring this requirement is met. Color shall be Munsell No: 7.0 GY 3.29/1.5 (Ameritech Telephone Green) on the outside. Inside the termination compartment, the tank wall, at minimum, shall be painted light grey. The manufacturer must furnish certification that the transformer will meet ANSI Standard C57.12.29-1988 on finish.
Q.
The successful vendor shall provide certified test reports, which shall include core and winding losses, on the transformer supplied under this bid.
R.
Manufacturers are to submit certification that the transformer does not contain any measurable concentrations of PCBs.
S.
Transformer losses will be evaluated and combined with bid costs to determine successful bidder(s), using the City’s Transformer Loss Evaluation formula (Figure 2).
T.
Manufacturer will stencil appropriate part # on front of transformer (min. 3” high numbers).
U.
Transformers shall include three – 5/8” holes located in the bottom sill below the primary bushings for future installation of fault indicators. The holes shall be in a horizontal pattern and centered in the sill below the primary compartment. The holes shall be covered by a tamper-proof cover.
Revised 7/29/11
TRANSFORMER LOSS EVALUATION (20 Year) Lfe
=
Core and related no load losses
Lcu
=
Load Losses
Lt
=
Lfe
Pd
=
Typical Values Cost of demand/losses/KW demand only = $ 8.82/KW
Pe
=
Cost of energy losses/KWHR; incremental =
+
Lcu
=
Total Losses
$ .02249
Combined loss cost calculation: Assume load factor = 60% loss factor = 30%) Pd (Lfe)Pe =
Pd (Lcu)Pe =
=
demand only =
energy cost
=
Lfe x 8760 x $ .02249
(A.)
Total, core loss cost
=
demand only =
energy cost (B.)
Lfe x $ 8.82 x 12
Lcu x $ 8.82 x 12
= Lcu x 8760 x .3 x $ .02249
Total, load loss cost
=$
/Yr.
=$
/Yr.
=$
/Yr.
=$
/Yr.
=$
/Yr.
=$
/Yr.
Summary of cost Losses: (A.)
Annual cost of No Load Losses
____________________
(B.)
Annual cost of Load Losses
____________________
Total Annual Cost (Lt = Lfe
+ Lcu)
=
____________________
TOTAL ANNUAL COST $________________ x 20 Years $ _______________ Figure 2
Revised 7/29/11
