2.3.2.2
Equipment Enclosure Grounding
Provide equipment enclosures with a ground bus and connectors in accordance
with National Electrical Code. Connect electrical equipment to the
grounding system specified in Division 16, "Electrical."
2.3.2.3
Insulation and Weatherproofing
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NOTE: Use this paragraph only when equipment is
exposed to the atmosphere.
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Insulate and weatherproof electrical enclosures exposed to the atmosphere.
The enclosures shall conform to specification for insulation and enclosure
for roof housing in paragraph entitled "Housing."
2.3.2.4
Wiring
Wiring design and installation shall be in accordance with NFPA 70 and as
specified.
2.3.3
Transformer-Rectifier (T-R) Set
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NOTE: T-R voltage should be 50 KV DC average as a
minimum. Sump must be covered and piped to an
oil-water separator if penthouse is not covered by a
weather enclosure.
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Enclose the high voltage rectifying equipment in the sealed transformer
case to form a single enclosure. The enclosure shall meet the requirements
of NEMA Type 3R construction as described in NEMA ICS 6. Provide
oil-filled, air-cooled type transformer designed and shielded for
precipitator service. Equip the transformer case with, at a minimum, the
following items: connection box, grounding connection, filling connection,
drain and sampling valves, thermometer, oil and vacuum gages, and high
temperature alarm. Provide sump to contain the oil which may leak from the
transformer. Provide rectifier with concentric pipe and guard conductors
between power supply and precipitator. Voltage supply shall be rated for
[_____] volts. T-R capacity shall be [_____] KVA maximum. T-R output
voltage rating shall be [_____] kV minimum. T-R shall operate at 60
percent to 100 percent of its current rating at normal operating conditions.
2.3.3.1
Rectifier
Provide oil immersed, solid state silicone type rectifier. Mount within
the transformer case and equip with necessary surge equalizers and
suppressors. Arrange interior parts to facilitate circulation of oil for
adequate cooling.
2.3.3.2
Grounding Switches
Provide each transformer-rectifier set with a five-position grounding
switch to permit grounding of both bushings; full-wave power to one
bushing, grounding of the other bushing and vice versa; half-wave power to
both bushings. Provide a bus duct between the power supply and the
SECTION 15862N
Page 26
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