REVISION NO.
TPD-General
3
Pad-mount Distribution
Transformer General
Specification Outline
1.0
EFFECTIVE DATE
APEGGA Permit #
P0850
SPECIFICATION NO.
PAGE
February 2008
1 of 3
PREPARED BY: H. Malik
REVIEWED BY: Original Reviewed by
Bob Chanasyk
APPROVED BY: Original Approved By
Garth Ryland, February 1, 2008
SCOPE
1.1
60 cycle, 65oC rise continuous rating, type ONAN, five legged core, dead-front padmounted distribution unit consisting of transformer and cable entrance compartment with
provision for separable insulated high voltage connectors; complying with the following CSA
Standards:
:
2.0
a)
CSA C227.3 – 06 Single Phase pad-mounted Distribution Transformers
b)
CSA C227.4 – 06 Three Phase pad-mounted Distribution transformers
TAPS
When specified, one of the following shall be supplied:
3.0
Alternate 1:
Four high-voltage taps at 2½ percent of rated voltage, two FCAN and two RCBN.
Alternate 2:
Four high-voltage taps at 2½ percent of rated voltage, three FCAN and one RCBN.
Alternate 3:
Four externally operable high-voltage taps at 2 1/2 percent of rated voltage, one
FCAN and three RCBN.
HIGH VOLTAGE SECTION
Specification numbers ending with PDL refer to units with a loop-feed arrangement and those
ending with PDR refer to units with a radial-feed arrangement.
3.1.
Bushings, Parking Stands, and Switches:
All transformers, including Delta Wound 24940 Volt transformers shall come complete
with externally clamped, bushing wells with removable studs either ELASTIMOLD model
#K1601PCC-R or RTE Model #2638372C02R and installed inserts ELASTIMOLD model
#2701A4, Chardon Insert Model #9U02BAB001RING or Cooper Insert model LBI 225. Other
models of bushing wells and inserts must be approved by the ATCO Electric standards
department. Inserts shall be grounded to the tank wall with a #14 copper wire.
3.1.1
Three-phase, loop-feed unit:
The high-voltage section shall house a primary feed-through arrangement consisting
of six bushings and shall include six parking stands. The feed-through arrangement
shall come complete with an RTE three-phase, four position, oil immersed,
sectionalizing V-blade switch MODEL #2200903C21M or equivalent.
3.1.2
Three-phase, radial-feed unit:
The high-voltage section shall include three bushings and three parking stands.
SPECIFICATION NO.
REVISION NO.
TPD-General
3.2
EFFECTIVE DATE
3
PAGE
February 2008
2 of 3
Fusing:
The transformer shall be supplied with Flapper Style RTE Bay-O-Net weak-link fuse(s) for
the kVA size of the transformer and oil-immersed, partial-range, current-limiting fuse(s) coordinated in series with the weak-link fuse(s).
4.0
3.2.1
All three phase delta wound transformers shall come complete with load sensing,
weak link under oil fuses rated for the transformer. (See CSA C227.4 - 06)
3.2.2
The transformer cable entrance compartment shall come complete with a bay-o-net
hatch as per CSA C227.4 - 06.
LOW-VOLTAGE SECTION
4.1
Single-Phase:
One piece secondary bushings with a seven-hole spade shall be used.
4.2
Three-Phase:
The low-voltage section shall house the tap-changing device (when required) although the
tap and wrench type are preferred other types will be accepted. Low-voltage bushings shall
have spade terminals in accordance with CSA, except six hole spades as per Fig 11(b)
shall be provided for 500-1000 kVA 600 and 480 volt transformers. When of the
clamped type, the bushings shall be externally clamped.
5.0
ENCLOSURE HEIGHT
Enclosure height other than what is specified in CSA will be accepted.
6.0
ACCESSORIES
6.1
The transformer shall be supplied complete with oil.
6.2
Exterior finish shall be in accordance with CSA and the color shall be Seafoam Green.
6.3
Three Phase Transformers 75 kVA to 1000 kVA shall come complete with a drain valve with
plug and liquid-level gauge.
6.4
All transformers 1000 kVA and larger shall also include an oil-maintenance package
consisting of:
a.
b.
c.
d.
7.0
25.4 mm drain valve with plug
top filter-press connection
thermometer, maximum indicating type
liquid-level gauge
TANK MARKINGS
SPECIFICATION NO.
REVISION NO.
TPD-General
8
9
10
EFFECTIVE DATE
3
PAGE
February 2008
3 of 3
7.1
All single-phase transformers shall have the exterior tank markings as per CSA, including
the utility stock code number. In addition to the information on the external tag, the kVA, HV
& LV shall be stenciled on the front of the hood.
7.2
All three-phase transformers shall have the exterior tank markings as per CSA including the
utility stock code number and gross weight. In addition to the information on the external
tag, the kVA, HV & LV shall be stenciled on the front of the door as shown in CSA.
7.3
The nameplate of all 1 MVA and larger transformers shall include the ATCO Electric
equipment number (ATCO EQ# (7 digits)).
IMPEDANCE
8.1
Three phase transformers 150 kVA to 1000 kVA with 277/480 V secondary shall have a
minimum impedance of 5%.
8.2
Other transformers shall have no minimum impedance unless specified.
MISCELLANEOUS
9.1
Suppliers shall provide a set of dimensioned outline drawings including the ATCO Electric
equipment number(ATCO EQ# (7 digits)) on all 1 MVA and larger transformers as well as
guaranteed performance specifications for the transformer bid upon with each quote.
Transformer production tests shall be those required by CSA. Copies of the test results shall
be forwarded to ATCO Electric upon request.
9.2
ATCO Electric shall be notified by the manufacturer of any transformer(s) which exceed the
manufacturer's guaranteed performance specification by more than the CSA allowable
tolerance.
BONDING STRAPS
The bonding strap(s) between the transformer case and the door(s) shall be of extra flexible braided
copper and shall have a current capacity equal to #6 copper.
11
DOORS
"Clamshell" door design is not acceptable for three phase units.
12
13
TRANSFORMER OIL
12.1
The transformer liquid insulant shall be class “B” as per latest edition of CSA C50. PCB
concentrations in the transformer oil shall not exceed 2 ppm and 2 ppm shall be stamped on
the nameplate as per CSA.
12.2
A non-PCB sticker shall be applied as per CSA.
TANK MECHANICAL FEATURES
Three phase transformer tanks shall come complete with either a bolted cover or a manhole large
enough to access both the currents limiting fuses and bay-o-net fuses.