1. Type:
Outdoor use, Oil-immersed, OA/FA/FA, 3 Windings with
rubber diaphragm conservator vented via silica gel dehydrating breather,
On-load-tap changer, manufactured according to ANSI C57.12.00 Std., All Copper
Windings, For use as a Step-down transformer in an electric utility
transmission substation. Complete with standard accessories.
2. Rating:
HV -
30/40/50 MVA
LV -
30/40/50 MVA
TV -
12/16/20 MVA
3. Cooling Method:
OA/FA1/FA2
4. Rated Voltage:
HV - 138KV
LV - 69KV
TV - 13.2KV
5. Tap Voltage: HV
Side OLTC: 138 KV + 8, - 12 x 1.0%, 21
Taps
6. OLTC:
ABB type UZFRT 550/300, 138,000
Volts, 3 Phase, 60 Hz, 21 positions,
With Motor Drive Mechanism type
BUF 3,
Motor : 460 Volts, 3 Phase, 60 Hz
Contactors: 230 Volts AC,
Position Transmitter: 230 Volts
AC
Heating Element : 230 Volts AC
With Manual/Automatic Change
over-switch, Raise & Lower
pushbuttons.
7. BIL:
7.1 Winding: HV –
650 KV
LV -
350 KV
Neutral – 150 KV
TV -
110 KV
7.2 Bushing: HV
- 650 KV
LV -
350 KV
Neutral - 150 KV
TV - 150 KV
7.3 Frequency : 60 Hz
7.4 Connection:
HV - Star
with Neutral (Auto-Star) brought out to a bushing
LV -
Star with Neutral (Auto-Star) brought out to a bushing
TV -
Delta
7.5 Vector Group : Yyna0d1
7.6 Guaranted Losses at rated voltage,
frequency, unity pf & @ 85 deg C (50 MVA):
No -Load Loss: 18.6 KW
Load Loss @ 50 MVA: 157.6 KW
Efficiency : 99.65%
@ 50 MVA( Without Auxiliary Loss)
7.7 Temperature Rise Limits:
Oil : 65 deg C
Winding: 65 deg C
7.8 % Impedances @ 85 deg C:
HV – LV@ 50 MVA HV - TV@ 20 MVA LV - TV@ 20 MVA
8L
- 149,040 V -
10.28 - 10.45
N
- 138,000 V -
10.50 - 10.31 - 5.6
12R
- 121,440 V -
11.09 - 10.52
8. Audible Sound Level @ 50 MVA
with all fans running: 72dB
9. Service Condition:
Maximum ambient air
temperature:
40 deg C
Average ambient air temperature
for any 24h period: 30 deg C
Maximum
altitude above sea level: 1000 meters
Maximum
ambient relative humidity: 88%
Mean
annual rainfall:
2400 mm
Maximum
wind velocity:
220 km/hr
Maximum
seismic factor:
0.45g
10. CONSTRUCTIONS
a) Core:
The core
of the transformer will be constructed of the highest quality, non-aging high
permeability, cold-rolled gain-oriented
silicon steel sheet especially suitable for the purpose. Every care will
be taken during slitting and cutting process to avoid burrs. Both sides of each
sheet will be special glass film insulated on to minimize eddy current losses.
The cores will be carefully assembled and rigidly clamped to ensure adequate
mechanical strength to support the windings and also reduced vibration to
minimum under operating conditions.
b) Windings:
The winding of the transformer shall be made of high tensile strength electrolytic copper of
a high conductivity (Class A, in accordance with ANSI) and insulation material of high quality shall
be used. The windings shall be free from
burrs, scales and splinters.
The
insulation material of windings and connections shall not shrink, soften or
collapse during service. Thermally upgraded paper shall be used for conductor
insulation. The design, construction and treatment of windings shall give
proper consideration to all service factors, such as high dielectric and
mechanical strenght of insulation, coil characteristics, uniform electrostatic
flux distribution, prevention of corona formation, and minimum restriction to
oil flow.
Moreover,
under any load condition, none of the material used shall disintegrate,
carbonizer or become brittle under the action of hot oil.
The coils
must be capable of withstanding movement and distortion caused by abnormal
operating conditions. Adequate barriers shall be provided between windings and
core as well as between high voltage and low voltage windings. All leads or
bars from the windings to the terminal boxes and bushings shall be rigidly
supported. Stresses on coils and connections must be avoided.
Due to very
unfavorable short-circuit conditions and numerous short-circuits in the
network, special measures have to be taken to increase the capability of the
winding to withstand short-circuit currents. Winding and arrangement of coils
shall be designed so as to unify the initial potential distribution caused by
impulsive traveling waves, as much as possible, to avoid potential oscillation
and in order to withstand abnormal high voltage due to switching.
To increase
the capability of the transformer windings to witstand electromagnetic forces
under short circuit conditions, modern technology in design and construction
shall be applied. (e.g. low current density, provision of pressure limiting
devices and spring elements, use of perfectly dried pre-compressed pressboard,
maintaining a balance of ampere-turns between windings, ets.)
Measures
against coil displacement as generated by the radial and longitudinal forces
shall be considered. Computation of strength against these forces including the
description of the method being applied shall be submitted in detail.
The tank,
conservation, coolers and bushings shall be adequately braced to withstand
ocean shipment, and earthquake with seismic coeffecient of 0.45 g (horizontal)
c) Short Circuit Withstand Capability
The
transformer shall withstand the combined effects of thermal, mechanical and
electromagnetic stresses arising under short-circuit conditions based on the
maximum durations of fault:
Primary Winding: 2 seconds
Secondary Winding: 2 seconds
Tertiary Winding
2 seconds
The maximum
sustrained short-circuit current in each windings shall be stated by the
manufacturers. The maximum temperatures of the windings shall not exceed 250
deg C within the seconds duration of fault. All transformer accessories, parts,
components (CT's, bushings, tap-changer, etc.) shall be capable of withstanding
the cumulative effects of repeated mechanical and thermal over-stressing as
produced by short-circuits and loads above the nameplate rating.
For design
purposes, the following network data shall be take into consideration. The
available system fault currents as as follows (in rms):
138 KV:
Ik" 60 KA 69 KV : Ik" = 50 kA 13.2 KV : Ik" = 40 kA
The
transformer shall be capable of withstanding the resulting successive
short-circuits, without cooling to normal operating temperature between
successive occurrence of the short circuit, provided the accumulated duration
of short-circuit does not exceed the maximum duration permitted for single
short-circuit defined above.
The upper
limits of the symmetrical overcurrent due to such short-circuits as a multiple
of rated current shall also be specified by the manufacturer.
d)
Overload Capability
The
short-time overload rating and operation of the transformer shall be in
accordance with ANSI C57.92 or IEC 354. All other auxiliary equipment
(bushings, CT's, etc) affected shall be rated to match the transformer overload
rating.
e) Transformer Tanks:
The tank should have sufficient strength
to withstand full vacuum and internal pressure of 1.0 kg/cm2, with cooling
equipment & conservator connected. The tank cover will be clamped with
bolts and nuts, and will be provided with hand hole or manholes of suitable
size. All seams and joint will be oil tight. Guides within the tank will be
furnished to facilitate tanking and untanking, and to prevent movement of the
core and coil assembly, in transit. The casing will be provided with suitable
lugs for lifting the completely assembled transformer filled with oil. All
gaskets will be synthetic rubber bonded cork.
f) Radiators:
The transformer will be provided with a
number of sufficient radiators for self-cooled (OA) operation. The radiator
will be installed on the tank via radiator valves, so that each radiator can be
detached from the tank independently of the oil in the main tank. The radiator
valves will have the open and close positions clearly marked. Radiators will be
equipped with provisions for draining. Radiators shall be made of galvanized
steel.
g) Forced-air-cooling
system:
For forced-air-cooled (FA)
operation, the transformer will be provided with automatically controlled three
phase motor-fans actuated from winding temperature. Fan motor, weather proofed,
three phase, Hz, and will be thermal protected. The cooling-fans will be
mounted on the radiators and the control box will be mounted on the wall of the
tank. Motor Voltage: 460 VAC, 3 phase, 60 Hz.
h) On-load
tap-changer:
The
following tap-changer will be equipped on H.V. side for the regulation of
voltage under loading conditions.
Type Type
UZFRT 550/300
3
phase,60 Hz, 21 positions
Number of tap positions 21 taps positions (138KV + 8 X 1380
V, - 12 X 1380 V)
Manufacturer ABB
Motor Drive Mechanism:
Type: ABB
type BUF 3
Motor
Voltage: 460 Volts,
3 Phase, 60 Hz
Contactors
Voltage: 230 VAC
Position
Transmitter: 230 VAC
Heating
Element: 230 VAC
Motor-Drive Mechanism Accessories:
1. Standard
Accessories
2. Phase Failure Relay
3.Circuit
Breakers for Control & Auxiliary circuits
4. Accessories for
paralleling with 3 transformers using MASTER-
FOLLOWER method.
OLTC Accessories:
1. Oil Conservator
2. Oil Level Indicator with contacts for Alarm
3. Dehydrating Breather
4. Pressure Relief Valve/Device with contacts
for tripping
5. Pressure Relay with contacts for tripping
6. Oil Flow
Controlled Relay with contacts for alarm
6.
Thermoswitch Housing
7. Valve for oil
filtration mounted on the top
8. Valve for
oil filling, draining & filtration
9. Earthing
terminal
10. Prepared
for on - line oil filter unit
i) Oil
preservation system:
Conservator
system with sealed diaphragm will be used. Conservator with low-profile design
having a moisture-proof barrier made with an oil-resisting diaphragm will be
applied and placed at the level slightly higher than the transformer tank.
j) Bushings:
Primary: ABB type GOB
650-1250-0.3 Brown, Cat # 123 193-K
1250 Amps, Nominal Voltage: 170 KV
rms,
Phase to Earth Voltage:145 KV rms,
BIL: 650KV,
Creepage Distance: 4080 mm
Porcelain Color: Brown
Short end shield
Secondary: ABB type GOB 380-800-0.3 Brown, Cat #
123-185-K
800 Amps, Nominal Voltage: 100
KV rms,
Phase to Earth Voltage:72.5 KV
rms, BIL: 380 KV
Creepage Distance:2210 mm
Porcelain Color: Brown
Short end shield
Tertiary: CEDASPE s.p.a. Italy type Dt 30 Nf
1000
1000 Amps, Nominal Voltage: 36 KV,
Maximum Voltage to Ground: 30 KV, BIL:170 KV,
Creepage
Distance: 640 mm
Porcelain Color: Brown
Threaded Extended Rod
Neutral: CEDASPE
s.p.a. Italy type Dt 52 Nf 1000
1,000 Amps, Nominal Voltage: 52 KV
Maximum Voltage to Gound: 52 KV, BIL 250 KV,
Creepage Distance: 1080 mm
Porcelain color: Brown
Threaded Standard Rod
11. Complete with the following accessories:
11.1 One (1) Buchholz Relay with 2
contacts for alarm & tripping
11.2 Two (2) Dial type Oil Level
Indicators for Main Tank & OLTC with contacts for alarm.
11.3 One (1) Oil Temperature Indicator
& Relay type AKM OTI series 34 for alarm.
11.4 Three ( 3) Winding Temperature
Indicators & Relays for HV, LV & TV windings with 3 contacts each for
alarm, tripping & fan control, AKM type WTI series 35.
11.5 Qualitrol type self resetting
mechanical Pressure Relief Device with contacts for tripping
11.6 Conservator for main Tank - Sealed
Diaphragm constant pressure type.
11.7 Breather type conservator for OLTC.
11.8 Annunciators (Marshalling Kiosk)
11.9 Bushing Current Transformers
HV: 300/200/100:5A; 0.6 - B 0.5
LV & Neutral: 600/500/400/300/200/100:5A; C-400
TV : 1200/1000/900/800/600/500/400/300/200/100:5A; C-400
11.10 Galvanized Steel
Radiators
11.11 Bushing Terminals
HV- Universal 4 hole NEMA Flat
Terminals
LV- Universal 4 hole NEMA Flat
Terminals
TV – Universal Multi -hole NEMA
Flat Terminals
11.12 Sets of Surge Arresters mounted nearest to
the HV, LV & TV transformer bushings, with Surge Counters & 4/0 AWG THW
Copper conductors connected to Grounding terminals.
HV : 120 KV Voltage Rating, 98 KV MCOV,
Station Class, Polymer housing, Metal Oxide, Line Discharge Class 4 per IEC, 12
KJ/KV Energy capability 65 KA Pressure Relief Capability, Grey Silicone
Insulator ABB type PEXLIM-P Complete with top clamps to hold a 336.4 MCM
Aluminum Conductor and 4/0 AWG THW Copper green wire ground conductor connected
to ground terminal.
LV : 60 KV voltage Rating, 48 KV MCOV, Station
Class, Polymer housing, Metal Oxide, Line Discharge Class4 per IEC, 12 KJ/KV
Energy Capability 65 KA Pressure relief Capability, Grey Silicone Insulator,
ABB type PEXLIM-P Complete with top clamps to hold a 795 MCM Aluminum
Conductors and a 4/0 AWG THW Copper
green wire ground conductor connected to ground terminal.
TV :18 KV Voltage Rating, 15 KV MCOV Station
Class, Polymer housing, Metal Oxide, Line Discharge Class 3 per IEC, 9.0 KJ/KV
energy capability 65 KA pressure relief capability, Grey Silicone Insulator,
ABB type POLIM-S 15N Complete with top clamps to hold a 795 MCM Aluminum
Conductors and a 4/0 AWG THW Copper green wire ground conductor connected to
Ground terminal.
11.13 Neutral Conductor: 4/0 AWG THW Copper wire
colored green connected to ground pad.
11.14 Insulating Oil – Shell Diala B or
equivalent
11.15 With provision for Built-in OLTC
Insulating Oil Filter Machine, such as mounting brackets, connecting flange,
connecting valves, etc.
11.16 Cooling Fans must be 3 Phase, 460 VAC, 60
Hz, Winding Temperature Controlled for Automatic Operation, with
automatic/manual change over switch. With
Circuit breakers for motor overload & short circuit protection.
11.17 Grounding Pads for HV Arresters, LV
Arresters, TV Arresters & Neutral Cables.
11.18 Steel Ladder with caution marking
11.19 All External Power & Control cables
must be flexible, multicore, PVC
insulated & enclosed in conduit pipes & flexible hoses.
11.20 All power & control circuits must be
protected by circuit breakers.
11.21 Welded Tank Cover.
11.22 All wiring connections & terminations
must be ANSI standard using crimp type terminal lugs with insulator caps.
11.23 All wirings must be color-coded.
11.24 With replacement gaskets
11.25 Anchor Bolts
11.26 One (1) Spare bushing each for HV, LV
& TV
11.27 One (1)
Spare OLTC Tap Position Indicator for remote use
11.28 One Set -
Paralleling Equipment for 3 OLTC Power Transfomers using Master - Follower
method of OLTC Control.
12. TESTS:
The following tests shall be
carried out at the factory with the presence of user representative and records
of testing will be submitted.
12.1 Winding Resistance Tests
12.2 Turns Ratio Tests
12.3 Polarity & Phase Relation Tests on
rated voltage
12.4 Measurement of no-load losses and
excitation current @ 90%, 100% & 110% of rated secondary voltage @ rated
frequency on rated voltage connection.
12.5 Measurement of impedance voltage and load
loss tests at rated current and rated frequency.
12.6 Low frequency tests (Applied Voltage &
Induced Voltage) including partial discharge measurement in terms of RIV.
12.7 Leak Test.
12.8 Routine test certificate for the bushings,
current transformers and surge arresters shall be submitted.
12.9 Temperature Rise Test at OA, FA1 & FA2
ratings on the tapping with maximum losses.
12.10 Lightning Impulse Test on HV, LV , Neutral
& Tertiary terminals. (Full wave, Chopped wave & reduced full wave)
12.11 Audible Sound level Test at no-load and rated
frequency and with all fans operating.
12.12 Measurement of
zero-sequence impedance.
12.13 Insulation
Power factor
12.14 Insulation
Resistance Tests at ambient temperature.
12.15 Vacuum test on
transformer tank, conservator & radiators; and pressure test on tank and
oil-filled compartments.
12.16 Determination
of Capacitances (windings to ground & between windings)
12.17 Tests on
auxiliary equipment & accessories ( functional tests including cooling
control)
12.18 Voltage
regulation
12.19 Measurement of
the power taken by the fan and oil pumps motors.
12.20 Functional
tests on Tap Changer
12.21 Test on
Current Transformers ( Check on polarity, ratio & wiring)
12.22 Mechanical
inspection, ( check of layout, dimensions, nameplate data, clearances, etc)
12.23 Oil tests
12.24 Efficiency at
principal tap and full load for unity & 0.8 power factor.
13. SPECIAL TEST
Certificate of Short Circuit Test
on power transformers of similar rating shall be submitted.
14. Other Accessories, Tools
a. Pressure gauge with nitrogen tube and
automatic filling device which fill the transformer through the tube in case of
any leakage shall be supplied.
b. Three-dimensional
impact recorder with time period recording chart of at least 3 months for use
during transport of the transformers.
c. Silica
-gel breathers for main and OLTC conservators.
15. Painting
Special attention should be given to the protection of all
iron-work. The methods proposed and the means adopted should be fully described
in the offer.
All surfaces shall be thoroughly cleaned of rust, scale,
grease and dirt and other foreign matters and all imperfections shall be
removed by means of approved methods.
The following treatments shall be applied:
a. External surfaces
All steel surfaces shall be sand-blasted in accordance with
SIS 055900, and shall then be painted in the following sequence:
1. two (2) primer
coats: 2 x 35 um (micrometer)
Binder : epoxy
resin hardened with polyamide
Pigment:
titanium dioxide, zinc oxide, zinc
phosphate, tinting additives
2. one (1) intermediate coat: 35 um
Binder: epoxy resin hardened with polyamide
Pigment: titanium dioxide,
micaceous iron oxide, tinting additives
3. one (1) top coat (polyurethane base): 35 um
Binder: epoxy resin hardened with isocyanat
Pigment:
titanium dioxide, micaceous iron oxide, tinting additives
Coating
thickness: Total 140um
The
color code shall be Munsell Gray No. N7.0
b. Internal surfaces
Inside the transformers vessel, sand-blasting
shall be performed in accordance with SIS 055900. After that solvent-free,
oil-resistant coating shall be applied. The minimum dry film thickness shall be
40 um
1 comment:
The transformer spec gives good guidance. I wish I had stumbled on this suite when I was just starting out in transmission!
Post a Comment