35kV Class Equipment.
The top of the distribution class — covering 34.5 kV nominal system voltage for renewable collector systems and long rural feeders, with standard BIL of 150 kV per IEEE C57.12.00.
- Equipment categories
- 10
- Nominal voltage
- 34.5 kV
- Standard BIL
- 150 kV
Standards.
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IEEE C57.12.00
Liquid-immersed transformer general requirements — defines 35kV class BIL at 150 kV.
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IEEE C57.12.34
Three-phase pad-mounted compartmental transformers to 34.5 kV nominal system voltage.
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IEEE 386
Separable connectors — 200A and 600A elbows used on 35kV pad-mount transformers.
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IEEE 404
Extruded and laminated dielectric shielded cable joints (splices) rated for 35kV systems.
Equipment categories rated for 35kV.
Transformers
Distribution and power transformers — pad-mounted, dry-type, and substation units rated for 35kV class, including collector-system step-up units.
View categorySwitchgear
Metal-clad and metal-enclosed switchgear per IEEE C37.20.2 for 35kV indoor and outdoor installations.
View categoryCable Splices
Cold-shrink and heat-shrink splices for 35kV cable joints per IEEE 404 — collector-circuit and feeder joints.
View categoryCable Terminations
Indoor and outdoor terminations for 35kV cable ends at transformers, switchgear, and substations.
View categoryElbow Connectors
200A loadbreak and 600A deadbreak elbow connectors per IEEE 386 — separable connections at 35kV pad-mount transformers and sectionalizers.
View categoryJunction Cabinets
Pad- and vault-mounted cabinets housing 35kV underground distribution and collector taps.
View categoryMetering Equipment
Pad- and pole-mounted revenue metering equipment for 35kV-class utility and collector service.
View categoryFault Indicators
Overhead and underground fault indicators for 35kV distribution and collector circuits.
View categorySurge Arresters
Distribution and intermediate class arresters sized for 35kV system MCOV and energy class.
View categoryTransmission & Distribution Products
Line hardware and insulators for 35kV overhead distribution and collector circuits.
View categoryMedium-voltage classes.
In-plant industrial distribution and large motor feeders. 2.4-4.8 kV, 60 kV BIL.
View class 15kVThe dominant utility primary-distribution class. 12.47-13.8 kV, 95 kV BIL.
View class 25kVSuburban and rural utility distribution. 24.94 kV (25/28 kV), 125 kV BIL.
View classCollector systems and long rural feeders. 34.5 kV, 150 kV BIL.
You are hereFAQ.
What nominal system voltage does the 35kV class cover?
The 35kV class is applied to a nominal system voltage of 34.5 kV — the top of the medium-voltage distribution class. It is the standard voltage for wind and solar collector systems and for long rural distribution feeders.
The class designation refers to the equipment insulation rating, not the actual operating voltage. A “35kV class” transformer is rated for a maximum system voltage of 34.5 kV, with standard BIL of 150 kV per IEEE C57.12.00.
What is the standard BIL for 35kV class equipment?
Standard BIL for 35kV class equipment is 150 kV per IEEE C57.12.00. BIL — Basic Impulse Insulation Level — is the equipment's specified ability to withstand a standard impulse voltage wave without insulation breakdown.
It is coordinated with the surge arresters on the system. 34.5 kV is the highest nominal system voltage covered by IEEE C57.12.34 for three-phase pad-mounted compartmental transformers.
Why is the 35kV class used for collector systems?
Wind and solar projects aggregate many distributed generators over large sites. At 34.5 kV, a collector circuit carries the combined output of multiple turbines or inverter pads with lower current and line losses than a lower-voltage circuit would, which reduces conductor size and the number of feeders.
Because 34.5 kV is the top of the distribution class, collector systems can use standard 35kV-class pad-mount transformers, sectionalizers, cable, and separable connectors rather than transmission-class apparatus.
Where else is the 35kV class used?
Beyond renewable collector systems, the 35kV class serves long rural distribution feeders. The higher voltage relative to 15kV and 25kV lets a single feeder deliver power over long distances to dispersed rural loads with acceptable voltage drop and losses.
Utilities operating long rural circuits standardize on 34.5 kV pad-mount transformers, overhead line hardware, and underground cable accessories. See the 25kV class for the suburban and rural class below it.
What standards govern 35kV class equipment?
Liquid-immersed transformers — including pad-mount and substation units — are governed by IEEE C57.12.00 (general requirements) and C57.12.34 (three-phase pad-mounted compartmental, to 34.5 kV nominal). Dry-type units use IEEE C57.12.01.
Switchgear is governed by IEEE C37.20.2 (metal-clad) or C37.20.3 (metal-enclosed). Separable connectors use IEEE 386 (200A and 600A elbows). Cable splices and terminations use IEEE 404 and IEEE 48. Surge arresters use IEEE C62.11.
Sourcing 35kV equipment?
Send the category, nominal voltage, BIL, and quantities for a quote.
35kV class equipment for collector systems and rural feeders.
The 35kV class is the top of the medium-voltage distribution class. It covers a nominal system voltage of 34.5 kV — the standard voltage for wind and solar collector systems and for long rural distribution feeders. The higher voltage relative to the 15kV and 25kV classes lets a feeder carry the combined output of many generators, or deliver power to dispersed rural loads, over long distances with lower current and line losses. Equipment in this class is built to IEEE C57.12.00 and C57.12.34 for transformers, IEEE C37.20.2 for metal-clad switchgear, IEEE 386 for separable connectors, IEEE 404 for cable splices, and IEEE C62.11 for surge arresters, with standard BIL of 150 kV.
Hawk MV Supply sources 35kV-class equipment across 10 product categories — transformers, switchgear, cable splices and terminations, elbow connectors, junction cabinets, metering equipment, fault indicators, surge arresters, and transmission & distribution products. Because 34.5 kV is the top of the distribution class, collector systems use standard 35kV-class apparatus rather than transmission-class equipment. Contact us to develop part numbers and check stock and lead time across the linecard.