Issue: 1

P.O. No: 45-8156

Project No: 0260-89-005

Date: October 22,1990

SPECIAL SPECIFICATION

SECTION 16471

ELECTRICAL SPECIFICATION FOR 15KV POWER

OPERATED-PAD-MOUNTED GEAR

I. [GENERAL]{.underline}

1.01 The pad-mounted gear shall be in accordance with the one-line
diagram, and shall conform to the following specification.

1.02 The pad-mounted gear shall consist of a single self-supporting
enclo­sure, containing interrupter switches and power fuses with the
neces­sary accessory components, including sensing, controls, and control
power supply, all completely factory-assembled and operationally
checked.

1.03 Ratings

> The ratings at 60H3 for the integrated pad-mounted gear shall be as
> designated below.

Kv, Nominal\...\...\...\...\...\...\...\...\...\...\...\... 14.4

Kv, Maximum Design\...\...\...\...\...\...\...\...\..... 17.0

Kv, BIL\...\...\...\...\...\...\...\...\...\...\...\...\.... 95

Main Bus Continuous, Amperes\...\...\...\...\...\.... 600

Three-Pole Interrupter Switches

Continuous Amperes\...\...\...\...\...\...\...\... 600

Load Dropping, Amperes\...\...\...\...\...\..... 600

Two-Time Duty-Cycle Fault-Closing,

Amperes Rms Asymmetrical\...\...\...\...\... 22,400

Fuses with Integral Load Interrupter

Maximum, Amperes\...\...\...\...\...\...\...\..... 200E

Load Dropping, Amperes\...\...\...\...\...\..... 200

Two-Time Duty-Cycle Fault-Closing

Capability, Amperes Rms Asym-

metrical\...\...\...\...\...\...\...\...\...\.... 13,000

Fused with\...\...\...\...\...\...\...\...\...\..... 30E, slow

Short-Circuit Ratings

Amperes, Rms Symmetrical\...\...\...\...\...\... 12,500

Mva Three-Phase Symmetrical at

Rated Nominal Voltage\...\...\...\...\...\... 310

> The momentary and two-time duty-cycle fault-closing ratings of
> swit­ches, momentary rating of bus, interrupting ratings of fuses, and
> one-time duty-cycle fault-closing capabilities of fuses with integral
> load interrupters shall equal or exceed the short-circuit ratings of
> the pad-mounted gear.

1.04 Certification of Ratings

\(a\) The manufacturer of the pad-mounted gear shall be completely and
solely responsible for the performance of the basic switch and fuse
components as well as the complete integrated pad-mounted gear assembly
as rated.

\(b\) The manufacturer shall furnish certification of ratings of the
basic switch and fuse components and/or the integrated pad-mounted gear
assembly consisting of the switch and fuse components in combination
with the enclosure.

1.05 Compliance with Standards and Codes

> The pad-mounted gear shall conform to or exceed the applicable
> require­ments of the following standards and codes:

\(a\) Applicable safety and health standards promulgated pursuant to
Federal Occupational Safety and Health Act of 1970, as amended, which
are in effect 30 days prior to the date of quotation or bid.

\(b\) Article 710-21(e) in the National Electrical Code, which specifies
that the interrupter switches in combination with power fuses shall
safely withstand the effects of closing, carrying, and in­terrupting all
possible currents up to the assigned maximum short-circuit rating.

\(c\) All portions of ANSI, IEEE, and NEMA standards applicable to the
basic switch and fuse components.

1.06 Enclosure Design

\(a\) To ensure a completely coordinated design, the pad-mounted gear
assembly shall be constructed in accordance with the minimum
con­struction specifications of the f use and/or switch manufacturer to
provide adequate electrical clearances and adequate space for fuse
handling.

\(b\) In establishing the requirements for the enclosure design,
consi­deration shall be given to all relevant factors such as controlled
access and tamper resistance.

II [CONSTRUCTION \-- ASSEMBLY]{.underline}

2.01 Insulators

> The interrupter-switch and fuse-mounting insulators shall be of a
> cy­cloaliphatic expoxy resin system with characteristics and
> restrictions as follows:

\(a\) Operating experience of at least 10 years under similar
condi­tions.

\(b\) Adequate leakage distance established by test per IEC Publication
507, First Edition, 1975.

\(c\) Adequate strength for short-circuit stress established by test.

\(d\) Conformance with applicable ANSI standards.

\(e\) Homogeneity of the cycloaliphatic epoxy resin throughout each
insulator to provide maximum resistance to power arcs. Ablation due to
high temperatures from power arcs shall continuously expose more
material of the same composition and properties so that no change in
mechanical or electrical characteristics takes place because of
arc-induced ablation. Furthermore, any surface damage to insulators
during installation or maintenance of the pad-mounted gear shall expose
material of the same composition and properties so that insulators with
minor surface damage need not be replaced.

2.02 High-Voltage Bus

\(a\) Bus and interconnections shall consist of aluminum bar of 56% IACS
conductivity.

\(b\) Bus and interconnections shall withstand the stresses associated
with short-circuit currents up through the maximum rating of the
pad-mounted gear.

\(c\) Bolted aluminum-to-aluminum connections shall be made with a
suit­able number of 1/2\"-13 galvanized steel bolts and with two
Belle­ville spring washers per bolt, one under the bolt head and one
under the nut. Bolts shall be tightened to 50 ft-lbs torque.

\(d\) Before installation of the bus, all electrical contact surfaces
shall first be prepared by machine abrading to remove any alumi­num-oxide
film. Immediately after this operation, the electrical contact surfaces
shall be coated with a uniform coating of an oxide inhibitor and
sealant.

2.03 Ground-Connection Pads

\(a\) A ground-connection pad shall be provided in each compartment of
the pad-mounted gear.

\(b\) The ground-connection pad shall be constructed of 3/8\" thick
steel, which shall be nickel plated and welded to the enclosure, and
shall have a short-circuit rating equal to that of the inte­grated
assembly.

\(c\) Ground-connection pads shall be coated with a uniform coating of
an oxide inhibitor and sealing prior to shipment.

2.04 Low-Voltage Components

\(a\) All low-voltage components, including stored-energy operators and
source-transfer controls, shall be located in a grounded, steel-enclosed
compartment separate from high voltage to provide isola­tion and shall be
arranged to allow complete accessibility for test and/or maintenance
without exposure to high voltage.

\(b\) Low-voltage wiring, except for short lengths such as at terminal
blocks and the secondaries of sensing devices, shall be in grounded
conduit or raceways where necessary for isolation from high voltage.

III [CONSTRUCTION \-- ENCLOSURE INCLUDING OUTDOOR FINISH]{.underline}

3.01 Enclosure

\(a\) The pad-mounted gear enclosure shall be of unitized monocoque (not
structural-frame-and-bolted-sheet) construction to maximize strength,
minimize weight, and inhibit corrosion.

\(b\) A separate grounded, steel-enclosed low-voltage control
compart­ment shall be provided for source-transfer controls and
stored-energy operators.

\(c\) The basic material shall be 11-gauge hot-rolled, pickled and oiled
steel sheet.

\(d\) All structural joints and butt joints shall be welded, and the
external seams shall be ground flush and smooth.

\(1\) The gas-shielded short-circuiting transfer welding process shall
be employed to eliminate alkaline residues and to mini­mize distortion
and spatter.

\(2\) Any welds made by other than this method shall be ground and
sanded (wire brushed if internal) to remove all scale and alkaline
residues formed during welding.

\(e\) To guard against unauthorized or inadvertent entry, enclosure
construction shall not utilize any externally accessible hardware.

\(f\) The base shall consist of continuous 90-degree flanges, turned
inward and welded at the corners, for bolting to the concrete pad.

\(g\) The door openings shall have 90-degree flanges, facing outward,
that shall provide strength and rigidity as well as deep overlap­ping
between doors and door openings to guard against water entry. Flanges at
door openings of low-voltage control compartments shall be provided with
resilient compression gasketing around the en­tire door opening, and
shall provide strength and rigidity for effective compression of the
gasketing to prevent water entry.

\(h\) Enclosure top side edges shall overlap with roof side edges to
create a mechanical maze which shall allow free-flow ventilation of
high-voltage compartments to help keep the enclosure interior dry while
discouraging tampering or insertion of foreign objects.

\(i\) A heavy coat of insulating \"no-drip\" compound shall be applied
to the inside surface of the roof to minimize condensation of mois­ture
thereon.

\(j\) Insulating interphase and end barriers of NEMA GPO3-grade
fiber­glass-reinforced polyester shall be provided for each interrupter
switch and each set of power fuses where required to achieve BIL
ratings. Additional insulating barriers of the same material shall
separate the front compartments from the rear compartments and isolate
the tie bus.

\(k\) Full-length steel barriers shall separate adjoining compartments.

\(l\) Lifting tabs shall be removable. Sockets for the lifting-tab bolts
shall be blind-tapped. A resilient material shall be placed between the
lifting tabs and the enclosure to help prevent corro­sion by protecting
the finish against scratching by the tabs. To further preclude
corrosion, this material shall be closed-cell to prevent moisture from
being absorbed and held between the tab and the enclosure in the event
that lifting tabs are not removed.

\(m\) Inner barrier panels that meet the Rural Electrification
Associ­ation\'s requirements for \"dead-front\" and the requirements of
Section 381G of the National Electrical Safety Code (ANSI Standard C2)
shall be provided \-- one for each door opening providing ac­cess to high
voltage. These panels shall be secured in place with recessed pentahead
bolts. When so secured, they shall guard against inadvertent contact
with live parts.

\(n\) A steel-compartmented base spacer shall be provided to increase
the elevation of live parts in the pad-mounted gear above the mounting
pad by 24 inches.

3.02 Doors

\(a\) Doors shall be constructed of 11-gauge hot-rolled, pickled and
oiled steel sheet.

\(b\) Doors providing access to high voltage shall have door-edge
flanges that shall overlap with door-opening flanges and shall be formed
to create a mechanical maze that shall guard against water entry and
discourage tampering or insertion of foreign objects, but shall allow
free-flow ventilation to help keep the enclosure interior dry.

\(c\) Doors providing access to the low-voltage control compartment
shall have 90-degree flanges providing a deep overlap with the door
openings. To keep low-voltage components clean and dry, these doors
shall be fully gasketed.

\(d\) Doors shall have a minimum of three stainless-steel hinges and
hinge pins. The hinge pins shall be welded in place to guard against
tampering.

\(e\) In consideration of controlled access and tamper resistance, each
door (or set of double doors) shall be equipped with an automatic
three-point latching mechanism.

\(1\) The latching mechanism shall be spring loaded, and shall latch
automatically when the door is closed. All latch points shall latch at
the same time to preclude partial latching.

\(2\) A pentahead socket wrench or tool shall be required to actu­ate the
mechanism to unlatch the door and, in the same mo­tion, recharge the
spring for the next closing operation.

\(3\) The latching mechanism shall have provision for padlocking that
incorporates a means to protect the padlock shackle from tampering and
that shall be coordinated with the latches such that:

\(i\) It shall not be possible to unlatch the mechanism until the
padlock is removed, and

(ii)It shall not be possible to insert the padlock until the mechanism
is completely latched closed.

\(f\) Doors providing access to solid-material power fuses shall have
provisions to store spare fuse units or refill units.

\(g\) Each door shall be provided with a galvanized-steel door holder
located above the door opening. The holder shall be hidden from view
when the door is closed, and it shall not be possible for the holder to
swing inside the enclosure.

3.03 Louvers

\(a\) Rain-resistant louvers shall be provided on the doors providing
access to the low-voltage control compartment.

\(b\) Each louver shall have an inside baffle to protect against
inser­tion of foreign objects.

3.04 Finish

\(a\) During fabrication, the areas of structural parts which may later
become inaccessible, such as folded edges and overlapping members, shall
be given a phosphatizing bath and an iron-oxide zinc-chro­mate
anticorrosion primer to ensure that all surfaces are protec­ted.

\(b\) Any welds made by other than the gas-shielded short-circuiting
transfer welding process shall be ground and sanded (wire brushed if
internal) to remove all scale and alkaline residues formed during
welding.

\(c\) Full coverage at joints and blind areas shall be achieved by
pro­cessing enclosures independently of components such as doors and
roofs before assembly into the unitized structures.

\(d\) All exterior seams shall be filled and sanded smooth for neat
appearance.

\(e\) To remove oils and dirt, to form a chemically and anodically
neu­tral conversion coating to improve the finish-to-metal bond, and to
retard under-film propagation of corrosion, all surfaces shall undergo a
thorough pre-treatment process before any protective coatings are
applied.

\(f\) After pre-treatment, protective coatings shall be applied that
shall help resist corrosion and protect the steel enclosure. To
establish the capability of the finishing system to resist corro­sion and
protect the enclosure, representative test specimens shall
satisfactorily pass the following tests:

\(1\) 1500 hours of exposure to salt-spray testing per ASTM B 117 with:

\(i\) Underfilm corrosion not to extend more than 1/32\" from the
scribe; and

(ii)Loss of adhesion from bare metal not to extend more than 1/8\" from
the scribe.

\(2\) 1000 hours of humidity testing per ASTM D 2247 with no blis­tering
as evaluated per ASTM D 714.

\(3\) 500 hours of accelerated weathering testing per ASTM G 53 with no
chalking as evaluated per ASTM D 659, and no more than 15% reduction of
paint gloss as evaluated per ASTM D 523.

\(4\) Crosshatch adhesion testing per ASTM D 3359 Method B with no loss
of paint.

\(5\) 160-inch-pound impact adhesion testing per ASTM D 2794 with no
paint chipping or cracking.

Certified test abstracts substantiating the above capabilities shall be
furnished upon request.

\(g\) After the finishing system has been properly applied and cured,
welds along the enclosure bottom flange and around the door hinges shall
be coated with a wax-based anticorrosion moisture barrier to give these
areas added corrosion resistance.

\(h\) A resilient closed-cell material, such as PVC gasket, shall be
applied to the entire underside of the enclosure bottom flange to
protect the finish on this surface from scratching during handling and
installation. This material shall isolate the bottom flange from the
alkalinity of a concrete foundation to help protect against corrosive
attack.

\(i\) After the enclosure is completely assembled and the components
(switches, fuses, bus, etc.) are installed, the finish shall be
inspected for scuffs and scratches. Blemishes shall be carefully touched
up by hand to restore the protective integrity of the finish.

\(j\) The finish shall be light gray ANSI #70 (Munsell 5.0BG 7.0/0.4).

3.05 To guard against corrosion, all hardware (including door fittings,
fasteners, etc.), all operating-mechanism parts, and other parts sub­ject
to abrasive action from mechanical motion shall be of either non­ferrous
materials, or galvanized or zinc-plated ferrous materials.
Cadmium-plated ferrous parts shall not be used.

3.06 In consideration of tamper resistance, the enclosure shall conform
to or exceed the requirements of NEMA TR1-2.01, except that the test
values shall be increased to the following levels:

> Inward Axial Force \-- 50 pounds
>
> Prying Leverage Test \-- 75 foot-pounds
>
> Pull Test \-- 150 pounds

IV\. [BASIC COMPONENTS]{.underline}

4.01 Interrupter Switches

\(a\) Interrupter switches shall have a two-time duty-cycle
fault-clos­ing rating equal to or exceeding the short-circuit rating of
the short-circuit rating of the integrated pad-mounted gear assembly.
These ratings define the ability to close the interrupter switch twice
against a three-phase fault with asymmetrical current in at least one
phase equal to the rated value, with the switch remain­ing operable and
able to carry and interrupt rated current. Tests substantiating these
ratings shall be performed at maximum design

voltage with current applied for at least 10 cycles. Certified test
abstracts establishing such ratings shall be furnished upon request.

\(b\) Interrupter switches shall be operated by means of stored-energy
operators installed by the switch manufacturer.

\(c\) Each interrupter switch shall be completely assembled and adjusted
by the switch manufacturer on a single rigid mounting frame. The frame
shall be of welded steel construction such that the frame intercepts the
leakage path which parallels the open gap of the interrupter switch to
positively isolate the load circuit when the interrupter switch is in
the open position.

\(d\) Interrupter switch contacts shall be backed up by stainless-steel
springs to provide constant high contact pressure.

\(e\) Interrupter switches shall be provided with a single blade per
phase for circuit closing including fault closing, continuous current
carrying, and circuit interrupting. Spring-loaded auxili­ary blades shall
not be permitted. Interrupter switch blade sup­ports shall be permanently
molded in place in a unified insulated shaft constructed of the same
cycloaliphatic epoxy resin as the insulators.

\(f\) Circuit interruption shall be accomplished by use of an
interrup­ter which is positively and inherently sequenced with the blade
position. It shall not be possible for the blade and interrupter to get
out of sequence. Circuit interruption shall take place completely within
the interrupter, with no external arc or flame. Any exhaust shall be
vented in a controlled manner through a dei­onizing vent.

\(g\) Interrupter switches shall have a readily visible open gap when in
the open position to allow positive verification of correct switch
position.

\(h\) Mechanical anti-paralleling shall be provided to prevent
parallel­ing the two source interrupter switches.

\(i\) Key interlocks shall be provided to guard against opening
fuse-compartment door(s) unless both interrupter switches are locked
open.

\(j\) Ground studs shall be provided at all switch terminals. Ground
studs shall also be provided on the ground pad in each interrupter
switch compartment and on terminals and ground pads in any bus
compartment. The momentary rating of the ground studs shall equal or
exceed the short-circuit ratings of the pad-mounted gear.

4.02 Fuses

\(a\) Power Fuses

\(1\) Fuses shall be disconnect style, solid-material power fuses, and
shall utilize refill-unit-and-holder or fuse-unit-and-end-fitting
construction. The refill unit or fuse unit shall be readily replaceable
and low in cost.

\(2\) Fusible elements shall be nonaging and nondamageable so that it is
unnecessary to replace unblown companion fuses on sus­picion of damage
following a fuse operation.

\(3\) Fusible elements for refill units or fuse units rated 10 amperes
or larger shall be helically coiled to avoid mechan­ical damage due to
stresses from surges.

\(4\) Fusible elements, that carry continuous current, shall be
supported in air to help prevent damage.

\(5\) Each refill unit or fuse unit shall have a single fusible element
to eliminate the possibility of unequal current shar­ing in parallel
current paths.

\(6\) Power fuses shall have melting time-current characteristics that
are permanently accurate to within a maximum total tol­erance of 10% in
terms of current. Time-current characteris­tics shall be available which
permit coordination with pro­tective relays, automatic circuit reclosers,
and other fuses.

\(7\) Power fuses shall be capable of detecting and interrupting all
faults whether large, medium or small (down to minimum melting current),
under all realistic conditions of circui­try, with line-to-line or
line-to-ground voltage across the power fuse, and shall be capable of
handling the full range or transient recovery voltage severity
associated with these faults.

\(8\) All arcing accompanying power fuse operation shall be con­tained
within the fuse, and all arc products and gases evolved shall be
effectively contained within the exhaust control device during fuse
operations.

\(9\) Power fuses shall be equipped with a blown-fuse indicator that
shall provide visible evidence of fuse operation while installed in the
fuse mounting.

\(c\) Fuse-mounting jaw contacts shall incorporate an integral load
interrupter that shall permit live switching of fuses with a hook­stick.

\(1\) The integral load interrupter housing shall be of the same
cycloaliphatic epoxy resin as the insulators.

\(2\) The integral load interrupter shall be in the current path
continuously. Auxiliary blades or linkages shall not be used.

\(3\) Live switching shall be accomplished by a firm, steady open­ing
pull on the fuse pull ring with a hookstick. No separate
load-interrupting tool shall be required.

\(4\) The integral load interrupter shall require a hard pull to unlatch
the fuse to reduce the possibility of an incomplete opening operation.

\(5\) INternal moving contacts of the integral load interrupter shall be
self-resetting after each opening operation to per­mit any subsequent
closing operation to be performed immedi­ately.

\(6\) Circuit interruption shall take place completely within the
integral load interrupter with no external arc or flame.

\(7\) The integral load interrupter and the fuse shall be provided with
separate fault-closing contacts and current-carrying contacts. The fuse
hinge shall be self-guiding and, together with the fault-closing
contacts, shall guide the fuse into the current-carrying contacts during
closing operations. Circuit-closing inrush currents and fault currents
shall be picked up by the fault-closing contacts, not by the
current-carrying contacts or interrupting contacts.

\(8\) Integral load interrupters for power fuses shall have a one-time
duty-cycle fault-closing capability equal to the inter­rupting rating of
the fuse, and a two-time duty-cycle fault-closing capability of 13,000
amperes rms asymmetrical at 14.4 kv or 25 kv. The duty-cycle
fault-closing capability defines the level of available fault current
into which the fuse can be closed the specified number of times (once or
twice), without a quick-make mechanism and when operated vigorously
through its full travel without hesitation at any point, with the
integral load interrupter remaining operable and able to carry and
interrupt currents up to the emergency peak-load capabilities of the
fuse.

\(d\) Fuse terminal pads shall be provided with a two-position adapter,
making it possible to accommodate a variety of cable-terminating
devices.

\(e\) Ground studs shall be provided at all fuse terminals. One ground
stud shall also be provided on the ground pad in each fuse com­partment.
The momentary rating of the ground studs shall equal or exceed the
short-circuit ratings of the pad-mounted gear.

4.03 Stored-Energy Operators

\(a\) Stored-energy operators shall be provided to operate the
high-voltage source interrupter switches. They shall be motor charged
with solenoid trip-open and solenoid trip-closed operation.

\(b\) Stored-energy operators shall be equipped with an integral
quick-make quick-break mechanism installed by the switch manufacturer,
which shall store sufficient mechanical energy to open or close the
associated interrupter switch. The quick-make quick-break mechanism
shall swiftly and positively open and close the associ­ated source
interrupter switch independent of the speed of the charging motor or
manual handles.

\(c\) Stored-energy operators shall be equipped with tripping solenoids
to release the stored energy to open or close the associated source
interrupter switch in response to a control signal.

\(d\) Stored-energy operators shall be equipped with a charging motor
that shall charge the quick-make quick-break mechanism after each trip
operation when voltage is present on the associated source.

\(e\) Pushbuttons shall be provided to permit local electrical trip-open
and trip-closed operation. Local electrical operation shall be prevented
when the source-transfer control is in the automatic mode.

\(f\) Stored-energy operators shall be provided with an operation
selec­tor that shall have the following three positions:

\(1\) An operating position \-- when in this position, permits
me­chanical or electrical opening or closing of the source in­terrupter
switch.

\(2\) A lock position \-- when padlocked in this position, prevents all
mechanical and electrical operation.

\(3\) A charging position \-- when in this position, permits manual
charging of the quick-make quick-break mechanism while pro­hibiting
mechanical and electrical operation.

\(g\) Stored-energy operators shall be provided with a charging shaft
and a removable manual charging handle to allow manual charging of the
quick-make quick-break mechanism in the event control power is lost. The
manual charging shaft shall be accessible only when the operation
selector is in the \"charging\" position.

\(h\) Stored-energy operators shall be equipped with provision for local
mechanical trip-open and trip-closed operation in the event con­trol
power is lost.

\(i\) Stored-energy operators shall be located in a grounded,
metal-enclosed low-voltage control compartment. The control compartment
shall provide complete isolation from high voltage to help protect
operating personnel.

\(j\) Stored-energy operators shall be equipped with indicators to show
whether the quick-make quick-break mechanism is charged or dis­charged;
whether the associated source interrupter switch is in

the open or closed position; and whether the stored-energy opera­tor is
in the switch-open or switch-closed position.

\(k\) Each stored-energy operator shall be equipped with an operation
counter.

\(l\) Stored-energy operators shall be provided with a decoupling
fea­ture and a tool to permit decoupling of the stored-energy operator
from the associated source interrupter switch for testing and exercising
of the stored-energy operator and source-transfer with­out opening or
closing the interrupter switch and without exposure to high voltage. An
indicator shall be provided to show whether the operator is coupled or
decoupled. When the stored-energy operator is decoupled, the associated
interrupter switch shall be locked in the position it was in at the time
of decoupling. It shall not be possible to recouple the stored-energy
operator to the source interrupter switch unless the stored-energy
operator is in the same position (open or closed) as the source
interrupter switch.

\(m\) Mechanical cable interlocks shall be provided between each
stored-energy operator and each associated switch-compartment door to
prevent operation of the source interrupter switch when the asso­ciated
compartment door is open.

4.04 Source-Transfer Controls

\(a\) Operating Description

\(1\) The source-transfer control shall utilize the common-bus
primary-selective system. The normal condition shall be with one source
interrupter switch (for the preferred source, as field selected) closed
to energize the high-voltage bus, and with the other source interrupter
switch (for the alternate source) open with its associated circuit
available as a standby. The source-transfer control shall monitor the
con­dition of both power sources and shall initiate automatic switching
when the preferred-source voltage has been lost (or reduced to a
predetermined level) for a period of time suf­ficient to confirm that the
loss is not transient. The auto­matic switching shall open the
preferred-source interrupter switch and then close the alternate source
interrupter switch to restore power to the high-voltage bus.

\(2\) When normal voltage returns to the preferred source for a preset
time, the source-transfer control shall initiate re­transfer to the
preferred source if in the automatic return mode, or shall await manual
transfer if in the hold return mode. In the hold return mode, if the
alternate source fails and if the preferred source has been restored,
the source-transfer control shall initiate automatic retransfer to the
preferred source.

\(3\) In the automatic return mode, the source-transfer control shall
provide either open transition (nonparalleling) or closed transition
(paralleling) on retransfer, as field se­lected.

\(b\) Control Features

The following control features shall be provided:

\(1\) A selector switch for manual or automatic mode. In the man­ual
mode, automatic switching as described above shall be inhibited.

\(2\) Receptacles and plugs that shall provide for field selection of
the preferred source.

\(3\) Source-voltage indicating lamps of the push-to-test type that
shall indicate presence of correct voltage on each high-volt­age source.

\(4\) A field-adjustable time delay between loss of voltage and
initiation of automatic switching to confirm that loss of voltage on
either source is not temporary. The timer range shall be from 1/4 to 10
seconds.

\(5\) A field-adjustable time delay between return of voltage and
initiation of retransfer switching to confirm that return of voltage on
either source is not transient. The timer range shall be from 1/2 to 15
minutes.

\(6\) Selector switches to allow field selection of automatic re­turn or
hold return mode, as described above.

\(7\) Selector switches to allow field selection of open transition or
closed transition on retransfer, as described above.

\(8\) An indicating lamp which shall indicate that both stored-energy
operators are coupled to their respective interrupter switches (if
optional decoupling feature is specified) and are in the correct
positions; that the source-transfer con­trol is in the automatic mode;
that the operation selector for each stored-energy operator is in the
operating position; and that all control circuitry is properly connected
for automatic transfer.

\(9\) Pushbutton test switches shall be provided to simulate loss of
voltage on either source and to allow convenient field testing of the
entire source-transfer scheme.

(10)The source-transfer control shall not require adjustment to
compensate for a difference between system line-to-ground voltage and
the voltage-sensing device\'s rated nominal line-to-ground voltage.

\(c\) Construction Features

\(1\) Source-transfer controls shall employ solid-state electronic
components to provide the superior reliability and servicea­bility
required for use in power equipment.

\(2\) The surge withstand capability of all solid-state source-transfer
controls shall be verified by subjecting each device to both the ANSI
Surge Withstand Capability Test (ANSI Stan­dard C37.90a) and to a 5-kv,
3.75-joule capacitive-discharge test. For the capacitive-discharge test,
a suitable capaci­tor shall be charged to 5 kv, and shall then be used to
dis­charge 3.75 joule into each input circuit and each output circuit of
the solid-state device.

\(3\) To identify and eliminate components that might be prone to early
failure, all solid-state source-transfer controls shall be subjected to
a 168-hour screening test followed by a die­lectric test and a functional
check. For the screening test, the source-transfer control shall be
energized at rated con­trol voltage while subjected to maximum-design
operation temperature for 120 hours followed by 48 hours during which
the temperature is cycled repeatedly between maximum-design operating
temperature and room temperature.

\(4\) Source-transfer controls shall be located in the grounded,
metal-enclosed low-voltage control compartment with the stored-energy
operators. The control compartment shall pro­vide complete isolation from
high voltage to help protect operating personnel.

\(5\) All solid-state electronic components shall be mounted on printed
circuit boards to minimize the number of intercon­nections for increased
reliability.

\(6\) The printed circuit boards with all attached electronic com­ponents
shall receive a resilient, conformal, silicone-dip coating to provide
protection from the environment and from vibration. An exception shall
apply to components with mov­ing parts where the coating would interfere
with correct mechanical operation.

\(7\) For source-transfer-control connections not soldered directly to a
printed circuit board, all interconnecting-cable connec­tor pins and
receptacle contacts shall be gold-over-nickel plated to minimize contact
resistance.

\(d\) Voltage Sensing and Control Power

\(1\) Voltage sensing and control power shall be provided by three
capacitively coupled voltage sensors on the line side of each source
interrupter switch.

\(2\) To maximize usable cable-training space within the pad-moun­ted
gear, the voltage sensors shall directly replace the lower apparatus
insulators of the source interrupter swit­ches. Furthermore, the voltage
sensors shall be constant-current-output devices that do not require
primary fuses.

\(3\) The output of the voltage sensors shall be directly propor­tional
to line-to-ground voltage and shall have relay accu­racy over an ambient
temperature range of -40oF to +160oF.

\(4\) There shall be test jacks and adjustment screws to allow for
measuring and adjusting the voltage-sensor signal inputs.

\(5\) Each voltage sensor shall be equipped with a secondary-side
protective device to prevent damage to the voltage sensor in the event
that the secondary circuit is inadvertently opened or the burden is
removed.

\(e\) Source-side open-phase detection shall be provided to initiate
transfer on detection of source-side open-phase conditions caused by
utility-line burn-down, broken conductors, single-phase switch­ing,
equipment malfunctions, or single-phasing resulting from blown
source-side fuses. An on/off selector switch shall be included that
shall, in the off position, defeat the open-phase detection to allow
testing of the source-transfer control by means of an external
single-phase source.

\(f\) An overcurrent-lockout feature shall be provided to prevent an
automatic transfer operation that would close a source interrupter
switch into a fault. This feature shall include a lamp to indi­cate when
a lockout condition has occurred, a reset pushbutton for manual
resetting of the lockout condition, a pushbutton test switch to simulate
an overcurrent condition, and three current-sensor assemblies for each
source.

\(g\) Remote-indication provisions shall be provided to permit remote
monitoring of the presence or absence of preferred- and alternate-source
voltage; the operating mode of the source-transfer control (i.e.,
automatic or manual); the status of the indicating lamp furnished in
4.04(b)(8); and (where applicable) overcurrent lock­out.

V. [LABELING]{.underline}

5.01 Warning Signs

\(a\) All external doors providing access to high voltage shall be
pro­vided with \"Caution - High Voltage - Keep Out\" signs.

\(b\) The inside of each door providing access to high voltage shall be
provided with a \"Danger - High Voltage - Keep Out - Qualified Persons
Only\" sign.

\(c\) The inside of each door providing access to an interrupter switch
shall be provided with a warning sign indicating that \"Switch Blades
May Be Energized in Any Position.\"

\(d\) The inside of each door providing access to power fuses shall be
provided with a warning sign indicating that \"Fuses May Be Ener­gized in
Any Position.\"

\(e\) Any barriers used to prevent access to energized live parts shall
be provided with \"Danger - High Voltage - Qualified Persons Only\"
signs.

5.02 Nameplates, Ratings Labels, and Connection Diagrams

\(a\) The outside of each set of double doors providing access to high
voltage shall be provided with a nameplate indicating the
manufac­turer\'s name, catalog number, and model number.

\(b\) The inside of each set of double doors shall be provided with a
ratings label indicating the following: voltage ratings; main bus
continuous rating; short-circuit ratings (amperes, rms asymmetri­cal and
Mva three-phase symmetrical at rated nominal voltage); the type of fuse
and its ratings including duty-cycle fault-closing capability; and
interrupter switch ratings including duty-cycle fault-closing capability
and amperes, short-time, rms (momentary, asymmetrical and one-second,
symmetrical).

\(c\) The inside of each set of double doors shall be provided with a
three-line connection diagram showing interrupter switches, fuses with
integral load interrupter, voltage sensors, and bus along with the
manufacturer\'s model number.

VI\. [REQUIRED AUXILIARIES]{.underline}

6.01 End fittings or holders, and fuse units or refill units for
original installation, as well as one spare fuse unit or refill unit for
each fuse mounting, shall be furnished.

6.02 Connectors for all phase conductors, bronze body tin-plated, two
galva­nized steel bolts, two Belleville washers, No. 2 solid through 500
KC mil stranded copper.